AGW Observer

Observations of anthropogenic global warming

Archive for the ‘Climate claims’ Category

Global warming hiatus paper list, version 1.0 (224 papers)

Posted by Ari Jokimäki on April 24, 2018

For quite some time now I have been gathering papers relating to the global warming hiatus (GWH). GWH was a period in climate where Earth’s global surface temperature apparently warmed less than during the previous years. I have written about this before (here, here, and here), so I’m not going to make an in-depth explanation of the issue here.

Hiatus paper list methods

I have used Google Scholar with certain search phrases. Google Scholar is not best possible search engine for scientific literature searches but it seems to yield most extensive search results and is freely accessible. The problems with Google Scholar for these searches are mainly related to Google Scholar returning lots of results that are not peer-reviewed. Problems of Google Scholar shouldn’t matter much here, because I have gone through all the results from these searches by systematically inspecting each search result.

Search phrases used: “global warming hiatus”, “global warming slowdown”, “global warming slow-down”, “global warming pause”, “pause in global warming”, “global warming plateau”, “global warming stagnation”, “global warming has stopped”, “climate change hiatus”, “climate warming hiatus”, “global warming halted”, “global warming slowed”.

Additionally there are a few papers not captured by these searches, but which I have picked up from here and there. I know that there still are some relevant papers missing from the list that these searches have not captured but I will be adding more papers in the future.

Following papers are included to the list:
– Only peer reviewed papers are included. Book chapters, reports, editorials, or perspective/opinion/news articles are not included even if they have been published in peer-reviewed journals. It is not always straight-forward to identify peer-reviewed papers. For example, Nature has a habit of not indicating properly which of their papers are real research articles and which ones are just opinion or news articles. There are also plenty of journals which are not real scientific journals but pretend to be, and of course Google Scholar includes them in their database. As a result, the list below probably contains a few papers that are published in questionable journals.
– Abstract or title has to contain clear mention of GWH. Only papers mentioning the early 2000s hiatus are included, not the ones that discuss hiatus periods generally or discuss some other hiatus period if they don’t mention the early 2000s hiatus (I had to draw the line somewhere).

The list

The global warming hiatus paper list is given below in RIS format (which is one of commonly offered citation formats by journals). I have numbered the papers and the number is the first field for each paper (marked as “NR”, which is not in the official RIS format – I was going to use “M1” first, which is said to be “number” but decided to use NR instead because it is more descriptive). I haven’t edited the entries much but they are here mostly as the journals give them. It should be noted that different publishers unfortunately seem to have their own ideas of how to use the RIS format. For example, the first entry is from Nature and they use “L3” for additional URL and for DOI, even if DOI has its own “DO” tag. They also have a creative way to give publication year. Whoever designed the RIS format export in Nature, didn’t consider much of the possibility that someone might want to read these entries automatically.

The list contains 224 papers, but the numbering goes to 225 because I removed number 48 at some point because it turned out to be a non-peer-reviewed paper. The list is fairly complete to the end of 2016 (there are a few papers marked as 2017 papers but they have been published already in 2016 online which is why they have been included to this version).

There are a few papers that I suspect might not be peer-reviewed (mostly from Nature, see above), but the list will be polished in the future. I’m currently working on 2017 GWH papers and already there are over 300 papers in the list!

Here’s the list:

NR – 1
TY – JOUR
AU – Xie, Shang-Ping
AU – Kosaka, Yu
AU – Okumura, Yuko M.
TI – Distinct energy budgets for anthropogenic and natural changes during global warming hiatus
JA – Nature Geosci
PY – 2016/01//print
VL – 9
IS – 1
SP – 29
EP – 33
PB – Nature Publishing Group
SN – 1752-0894
UR – http://dx.doi.org/10.1038/ngeo2581
L3 – 10.1038/ngeo2581
M3 – Letter
L3 – http://www.nature.com/ngeo/journal/v9/n1/abs/ngeo2581.html#supplementary-information
AB – The Earth’s energy budget for the past four decades can now be closed1, and it supports anthropogenic greenhouse forcing as the cause for climate warming. However, closure depends on invoking an unrealistically large increase in aerosol cooling2 during the so-called global warming hiatus since the late 1990s (refs 3,4) that was due partly to tropical Pacific Ocean cooling5, 6, 7. The difficulty with this closure lies in the assumption that the same climate feedback applies to both anthropogenic warming and natural cooling. Here we analyse climate model simulations with and without anthropogenic increases in greenhouse gas concentrations, and show that top-of-the-atmosphere radiation and global mean surface temperature are much less tightly coupled for natural decadal variability than for the greenhouse-gas-induced response, implying distinct climate feedback between anthropogenic warming and natural variability. In addition, we identify a phase difference between top-of-the-atmosphere radiation and global mean surface temperature such that ocean heat uptake tends to slow down during the surface warming hiatus. This result deviates from existing energy theory but we find that it is broadly consistent with observations. Our study highlights the importance of developing metrics that distinguish anthropogenic change from natural variations to attribute climate variability and to estimate climate sensitivity from observations.
ER –

NR – 2
TY – JOUR
AU – Yao, Shuai-Lei
AU – Huang, Gang
AU – Wu, Ren-Guang
AU – Qu, Xia
PY – 2016
DA – 2016/01/01
TI – The global warming hiatus—a natural product of interactions of a secular warming trend and a multi-decadal oscillation
JO – Theoretical and Applied Climatology
SP – 349
EP – 360
VL – 123
IS – 1
AB – The globally-averaged annual combined land and ocean surface temperature (GST) anomaly change features a slowdown in the rate of global warming in the mid-twentieth century and the beginning of the twenty-first century. Here, it is shown that the hiatus in the rate of global warming typically occurs when the internally generated cooling associated with the cool phase of the multi-decadal variability overcomes the secular warming from human-induced forcing. We provide compelling evidence that the global warming hiatus is a natural product of the interplays between a secular warming tendency due in a large part to the buildup of anthropogenic greenhouse gas concentrations, in particular CO2 concentration, and internally generated cooling by a cool phase of a quasi-60-year oscillatory variability that is closely associated with the Atlantic multi-decadal oscillation (AMO) and the Pacific decadal oscillation (PDO). We further illuminate that the AMO can be considered as a useful indicator and the PDO can be implicated as a harbinger of variations in global annual average surface temperature on multi-decadal timescales. Our results suggest that the recent observed hiatus in the rate of global warming will very likely extend for several more years due to the cooling phase of the quasi-60-year oscillatory variability superimposed on the secular warming trend.
SN – 1434-4483
UR – https://doi.org/10.1007/s00704-014-1358-x
DO – 10.1007/s00704-014-1358-x
ID – Yao2016
ER –

NR – 3
TY – JOUR
T1 – The “Pause” in Global Warming: Turning a Routine Fluctuation into a Problem for Science
AU – Lewandowsky, Stephan
AU – Risbey, James S.
AU – Oreskes, Naomi
Y1 – 2015/09/14
PY – 2015
DA – 2016/05/01
N1 – doi: 10.1175/BAMS-D-14-00106.1
DO – 10.1175/BAMS-D-14-00106.1
JF – Bulletin of the American Meteorological Society
JO – Bull. Amer. Meteor. Soc.
SP – 723
EP – 733
VL – 97
IS – 5
PB – American Meteorological Society
AB – AbstractThere has been much recent published research about a putative ?pause? or ?hiatus? in global warming. We show that there are frequent fluctuations in the rate of warming around a longer-term warming trend, and that there is no evidence that identifies the recent period as unique or particularly unusual. In confirmation, we show that the notion of a pause in warming is considered to be misleading in a blind expert test. Nonetheless, the most recent fluctuation about the longer-term trend has been regarded by many as an explanatory challenge that climate science must resolve. This departs from long-standing practice, insofar as scientists have long recognized that the climate fluctuates, that linear increases in CO2 do not produce linear trends in global warming, and that 15-yr (or shorter) periods are not diagnostic of long-term trends. We suggest that the repetition of the ?warming has paused? message by contrarians was adopted by the scientific community in its problem-solving and answer-seeking role and has led to undue focus on, and mislabeling of, a recent fluctuation. We present an alternative framing that could have avoided inadvertently reinforcing a misleading claim.
SN – 0003-0007
UR – https://doi.org/10.1175/BAMS-D-14-00106.1
Y2 – 2017/11/08
ER –

NR – 4
TY – JOUR
AU – Liu, Wei
AU – Xie, Shang-Ping
AU – Lu, Jian
TI – Tracking ocean heat uptake during the surface warming hiatus
JA – Nature Communications
PY – 2016/03/30/online
VL – 7
SP – 10926
EP –
PB – The Author(s)
SN –
UR – http://dx.doi.org/10.1038/ncomms10926
L3 – 10.1038/ncomms10926
M3 – Article
L3 – https://www.nature.com/articles/ncomms10926#supplementary-information
AB – Ocean heat uptake is observed to penetrate deep into the Atlantic and Southern Oceans during the recent hiatus of global warming. Here we show that the deep heat penetration in these two basins is not unique to the hiatus but is characteristic of anthropogenic warming and merely reflects the depth of the mean meridional overturning circulation in the basin. We find, however, that heat redistribution in the upper 350?m between the Pacific and Indian Oceans is closely tied to the surface warming hiatus. The Indian Ocean shows an anomalous warming below 50?m during hiatus events due to an enhanced heat transport by the Indonesian throughflow in response to the intensified trade winds in the equatorial Pacific. Thus, the Pacific and Indian Oceans are the key regions to track ocean heat uptake during the surface warming hiatus.
ER –

NR – 5
TY – JOUR
AU – Smith, Doug M.
AU – Booth, Ben B. B.
AU – Dunstone, Nick J.
AU – Eade, Rosie
AU – Hermanson, Leon
AU – Jones, Gareth S.
AU – Scaife, Adam A.
AU – Sheen, Katy L.
AU – Thompson, Vikki
TI – Role of volcanic and anthropogenic aerosols in the recent global surface warming slowdown
JA – Nature Clim. Change
PY – 2016/10//print
VL – 6
IS – 10
SP – 936
EP – 940
PB – Nature Publishing Group
SN – 1758-678X
UR – http://dx.doi.org/10.1038/nclimate3058
L3 – 10.1038/nclimate3058
M3 – Letter
L3 – http://www.nature.com/nclimate/journal/v6/n10/abs/nclimate3058.html#supplementary-information
AB – The rate of global mean surface temperature (GMST) warming has slowed this century despite the increasing concentrations of greenhouse gases. Climate model experiments1, 2, 3, 4 show that this slowdown was largely driven by a negative phase of the Pacific Decadal Oscillation (PDO), with a smaller external contribution from solar variability, and volcanic and anthropogenic aerosols5, 6. The prevailing view is that this negative PDO occurred through internal variability7, 8, 9, 10, 11. However, here we show that coupled models from the Fifth Coupled Model Intercomparison Project robustly simulate a negative PDO in response to anthropogenic aerosols implying a potentially important role for external human influences. The recovery from the eruption of Mount Pinatubo in 1991 also contributed to the slowdown in GMST trends. Our results suggest that a slowdown in GMST trends could have been predicted in advance, and that future reduction of anthropogenic aerosol emissions, particularly from China, would promote a positive PDO and increased GMST trends over the coming years. Furthermore, the overestimation of the magnitude of recent warming by models is substantially reduced by using detection and attribution analysis to rescale their response to external factors, especially cooling following volcanic eruptions. Improved understanding of external influences on climate is therefore crucial to constrain near-term climate predictions.
ER –

NR – 6
TY – JOUR
AU – Wu, Huey-Tzu Jenny
AU – Lau, William K.-M.
C8 – 2015GL067371
TI – Detecting climate signals in precipitation extremes from TRMM (1998–2013)—Increasing contrast between wet and dry extremes during the “global warming hiatus”
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 43
IS – 3
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2015GL067371
DO – 10.1002/2015GL067371
SP – 1340
EP – 1348
KW – rainfall
KW – precipitation
KW – climate
KW – trends
KW – extreme
KW – drought
KW – 1630 Impacts of global change
KW – 1637 Regional climate change
KW – 1854 Precipitation
KW – 1812 Drought
KW – 1817 Extreme events
PY – 2016
AB – We investigate changes in daily precipitation extremes using Tropical Rainfall Measuring Mission (TRMM) data (1998–2013), which coincides with the “global warming hiatus.” Results show a change in probability distribution functions of local precipitation events (LPEs) during this period consistent with previous global warming studies, indicating increasing contrast between wet and dry extremes, with more intense LPE, less moderate LPE, and more dry (no rain) days globally. Analyses for land and ocean separately reveal more complex and nuanced changes over land, characterized by a strong positive trend (+12.0% per decade, 99% confidence level (c.l.)) in frequency of extreme LPEs over the Northern Hemisphere extratropics during the wet season but a negative global trend (-6.6% per decade, 95% c.l.) during the dry season. A significant global drying trend (3.2% per decade, 99% c.l.) over land is also found during the dry season. Regions of pronounced increased dry events include western and central U.S., northeastern Asia, and Southern Europe/Mediterranean.
ER –

NR – 7
TY – JOUR
AU – Zhang, Lei
PY – 2016
DA – 2016/11/01
TI – The roles of external forcing and natural variability in global warming hiatuses
JO – Climate Dynamics
SP – 3157
EP – 3169
VL – 47
IS – 9
AB – Global mean surface temperature (GMST) rising has slowed down since late 1990s, which is referred to as the global warming hiatus. There was another global warming hiatus event during 1940s–1960s. The roles of the external forcing and the natural variability in both global warming hiatuses are explored, using EOF analysis. The first two leading EOF modes of the 5-year running mean global sea surface temperature (SST) reflect the global warming scenario (EOF1) and the interdecadal Pacific oscillation (IPO)-like natural variability (EOF2), respectively. In observation, PC2 was in its positive phase (eastern Pacific cooling) during 1940s–1960s, which contributed to the previous warming hiatus. In addition, GMST trends are found to be negative during late 1950s and 1960s in most of the CMIP5 historical runs, which implies that the external forcing also contributed to the pause in the GMST rising. It is further demonstrated that it is the natural radiative forcing (volcanic forcing) that caused the drop-down of GMST in 1960s. The current global warming hiatus has been attributed to the eastern Pacific cooling/enhanced Pacific trade winds. It is shown that the PC2 switched to its positive phase in late 1990s, and hence the IPO-like natural variability made a contribution to the slowdown of GMST rising in the past decade. It is also found that the EOF1 mode (global warming mode) of the observed SST features a smaller warming in tropical Pacific compared to the Indian Ocean and the tropical Atlantic. Such inter-basin warming contrast, which is attributed to the “ocean thermostat” mechanism, has been suggested to contribute to the intensification of Pacific trade winds since late 1990s as well. Global warming hiatuses are also found in the future projections from CMIP5 models, and the spatial pattern of the SST trends during the warming-hiatus periods exhibits an IPO-like pattern, which resembles the observed SST trends since late 1990s.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-016-3018-6
DO – 10.1007/s00382-016-3018-6
ID – Zhang2016
ER –

NR – 8
TY – JOUR
UR – http://stacks.iop.org/1748-9326/9/i=6/a=064023
T1 – Observed and simulated temperature extremes during the recent warming hiatus
A1 – Jana Sillmann and Markus G Donat and John C Fyfe and Francis W Zwiers
Y1 – 2014
SP – 064023
JF – Environmental Research Letters
VL – 9
IS – 6
SN – 1748-9326
DO – 10.1088/1748-9326/9/6/064023
AB – The discrepancy between recent observed and simulated trends in global mean surface temperature has provoked a debate about possible causes and implications for future climate change projections. However, little has been said in this discussion about observed and simulated trends in global temperature extremes. Here we assess trend patterns in temperature extremes and evaluate the consistency between observed and simulated temperature extremes over the past four decades (1971–2010) in comparison to the recent 15 years (1996–2010). We consider the coldest night and warmest day in a year in the observational dataset HadEX2 and in the current generation of global climate models (CMIP5). In general, the observed trends fall within the simulated range of trends, with better consistency for the longer period. Spatial trend patterns differ for the warm and cold extremes, with the warm extremes showing continuous positive trends across the globe and the cold extremes exhibiting a coherent cooling pattern across the Northern Hemisphere mid-latitudes that has emerged in the recent 15 years and is not reproduced by the models. This regional inconsistency between models and observations might be a key to understanding the recent hiatus in global mean temperature warming.
ER –

NR – 9
TY – JOUR
AU – Seneviratne, Sonia I.
AU – Donat, Markus G.
AU – Mueller, Brigitte
AU – Alexander, Lisa V.
TI – No pause in the increase of hot temperature extremes
JO – Nature Climate Change
PY – 2014/02/26/online
VL – 4
SP – 161
PB – Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
UR – http://dx.doi.org/10.1038/nclimate2145
DO – 10.1038/nclimate2145
L3 – https://www.nature.com/articles/nclimate2145#supplementary-information
AB – Observational data show a continued increase of hot extremes over land during the so-called global warming hiatus. This tendency is greater for the most extreme events and thus more relevant for impacts than changes in global mean temperature.
ER –

NR – 10
TY – JOUR
AU – Schmidt, Gavin A.
AU – Shindell, Drew T.
AU – Tsigaridis, Kostas
TI – Reconciling warming trends
JO – Nature Geoscience
PY – 2014/02/27/online
VL – 7
SP – 158
PB – Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
UR – http://dx.doi.org/10.1038/ngeo2105
DO – 10.1038/ngeo2105
AB – Climate models projected stronger warming over the past 15 years than has been seen in observations. Conspiring factors of errors in volcanic and solar inputs, representations of aerosols, and El Niño evolution, may explain most of the discrepancy.
ER –

NR – 11
TY – JOUR
AU – Santer, Benjamin D.
AU – Bonfils, Céline
AU – Painter, Jeffrey F.
AU – Zelinka, Mark D.
AU – Mears, Carl
AU – Solomon, Susan
AU – Schmidt, Gavin A.
AU – Fyfe, John C.
AU – Cole, Jason N. S.
AU – Nazarenko, Larissa
AU – Taylor, Karl E.
AU – Wentz, Frank J.
TI – Volcanic contribution to decadal changes in tropospheric temperature
JO – Nature Geoscience
PY – 2014/02/23/online
VL – 7
SP – 185
PB – Nature Publishing Group
UR – http://dx.doi.org/10.1038/ngeo2098
DO – 10.1038/ngeo2098
L3 – https://www.nature.com/articles/ngeo2098#supplementary-information
AB – Despite continued growth in atmospheric levels of greenhouse gases, global mean surface and tropospheric temperatures have shown slower warming since 1998 than previously1,2,3,4,5. Possible explanations for the slow-down include internal climate variability3,4,6,7, external cooling influences1,2,4,8,9,10,11 and observational errors12,13. Several recent modelling studies have examined the contribution of early twenty-first-century volcanic eruptions1,2,4,8 to the muted surface warming. Here we present a detailed analysis of the impact of recent volcanic forcing on tropospheric temperature, based on observations as well as climate model simulations. We identify statistically significant correlations between observations of stratospheric aerosol optical depth and satellite-based estimates of both tropospheric temperature and short-wave fluxes at the top of the atmosphere. We show that climate model simulations without the effects of early twenty-first-century volcanic eruptions overestimate the tropospheric warming observed since 1998. In two simulations with more realistic volcanic influences following the 1991 Pinatubo eruption, differences between simulated and observed tropospheric temperature trends over the period 1998 to 2012 are up to 15% smaller, with large uncertainties in the magnitude of the effect. To reduce these uncertainties, better observations of eruption-specific properties of volcanic aerosols are needed, as well as improved representation of these eruption-specific properties in climate model simulations.
ER –

NR – 12
TY – JOUR
AU – Easterling, David R.
AU – Wehner, Michael F.
C8 – L08706
TI – Is the climate warming or cooling?
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 36
IS – 8
SN – 1944-8007
UR – http://dx.doi.org/10.1029/2009GL037810
DO – 10.1029/2009GL037810
SP – n/a
EP – n/a
KW – global warming
KW – climate change
KW – 1620 Climate dynamics
KW – 1610 Atmosphere
KW – 3305 Climate change and variability
KW – 3337 Global climate models
PY – 2009
AB – Numerous websites, blogs and articles in the media have claimed that the climate is no longer warming, and is now cooling. Here we show that periods of no trend or even cooling of the globally averaged surface air temperature are found in the last 34 years of the observed record, and in climate model simulations of the 20th and 21st century forced with increasing greenhouse gases. We show that the climate over the 21st century can and likely will produce periods of a decade or two where the globally averaged surface air temperature shows no trend or even slight cooling in the presence of longer-term warming.
ER –

NR – 13
TY – JOUR
AU – Huber, Markus
AU – Knutti, Reto
TI – Natural variability, radiative forcing and climate response in the recent hiatus reconciled
JA – Nature Geoscience
PY – 2014/08/17/online
VL – 7
SP – 651
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/ngeo2228
L3 – 10.1038/ngeo2228
M3 –
L3 – https://www.nature.com/articles/ngeo2228#supplementary-information
AB – Global mean surface warming over the past 15 years or so has been less than in earlier decades and than simulated by most climate models1. Natural variability2,3,4, a reduced radiative forcing5,6,7, a smaller warming response to atmospheric carbon dioxide concentrations8,9 and coverage bias in the observations10 have been identified as potential causes. However, the explanations of the so-called ‘warming hiatus’ remain fragmented and the implications for long-term temperature projections are unclear. Here we estimate the contribution of internal variability associated with the El Niño/Southern Oscillation (ENSO) using segments of unforced climate model control simulations that match the observed climate variability. We find that ENSO variability analogous to that between 1997 or 1998 and 2012 leads to a cooling trend of about -0.06 °C. In addition, updated solar and stratospheric aerosol forcings from observations explain a cooling trend of similar magnitude (-0.07 °C). Accounting for these adjusted trends we show that a climate model of reduced complexity with a transient climate response of about 1.8 °C is consistent with the temperature record of the past 15 years, as is the ensemble mean of the models in the Coupled Model Intercomparison Project Phase 5 (CMIP5). We conclude that there is little evidence for a systematic overestimation of the temperature response to increasing atmospheric CO2 concentrations in the CMIP5 ensemble.
ER –

NR – 14
TY – JOUR
AU – Hawkins, Ed
AU – Edwards, Tamsin
AU – McNeall, Doug
TI – Pause for thought
JA – Nature Climate Change
PY – 2014/02/26/online
VL – 4
SP – 154
EP –
PB – Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
SN –
UR – http://dx.doi.org/10.1038/nclimate2150
L3 – 10.1038/nclimate2150
M3 –
L3 –
AB – The recent slowdown (or ‘pause’) in global surface temperature rise is a hot topic for climate scientists and the wider public. We discuss how climate scientists have tried to communicate the pause and suggest that ‘many-to-many’ communication offers a key opportunity to directly engage with the public.
ER –

NR – 15
TY – JOUR
A1 – Kaufmann, Robert K.
A1 – Kauppi, Heikki
A1 – Mann, Michael L.
A1 – Stock, James H.
T1 – Reconciling anthropogenic climate change with observed temperature 1998–2008
Y1 – 2011/07/19
JO – Proceedings of the National Academy of Sciences
SP – 11790
EP – 11793
DO – 10.1073/pnas.1102467108
N1 – 10.1073/pnas.1102467108
M3 – 10.1073/pnas.1102467108
VL – 108
IS – 29
UR – http://www.pnas.org/content/108/29/11790.abstract
N2 – Given the widely noted increase in the warming effects of rising greenhouse gas concentrations, it has been unclear why global surface temperatures did not rise between 1998 and 2008. We find that this hiatus in warming coincides with a period of little increase in the sum of anthropogenic and natural forcings. Declining solar insolation as part of a normal eleven-year cycle, and a cyclical change from an El Nino to a La Nina dominate our measure of anthropogenic effects because rapid growth in short-lived sulfur emissions partially offsets rising greenhouse gas concentrations. As such, we find that recent global temperature records are consistent with the existing understanding of the relationship among global surface temperature, internal variability, and radiative forcing, which includes anthropogenic factors with well known warming and cooling effects.
ER –

NR – 16
TY – JOUR
AU – Kamae, Youichi
AU – Shiogama, Hideo
AU – Watanabe, Masahiro
AU – Kimoto, Masahide
C8 – 2014GL061062
TI – Attributing the increase in Northern Hemisphere hot summers since the late 20th?century
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 14
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL061062
DO – 10.1002/2014GL061062
SP – 5192
EP – 5199
KW – climate hiatus
KW – hot summers
KW – PDO
KW – AMO
KW – 0429 Climate dynamics
KW – 1610 Atmosphere
KW – 1616 Climate variability
KW – 1635 Oceans
KW – 1626 Global climate models
PY – 2014
AB – Anomalously high summertime temperatures have occurred with increasing frequency since the late 20th?century. It is not clear why hot summers are becoming more frequent despite the recent slowdown in the rise in global surface air temperature. To examine factors affecting the historical variation in the frequency of hot summers over the Northern Hemisphere (NH), we conducted three sets of ensemble simulations with an atmospheric general circulation model. The model accurately reproduced interannual variation and long-term increase in the occurrence of hot summers. Decadal variabilities in the Pacific and Atlantic Oceans accounted for 43?±?27% of the recent increase over the NH middle latitudes. In addition, direct influence of anthropogenic forcing also contributes to increasing the frequency since the late 20th?century. The results suggest that the heat extremes can become more frequent in the coming decade even with the persistent slowdown in the global-mean surface warming.
ER –

NR – 17
TY – JOUR
AU – Hunt, B. G.
PY – 2011
DA – 2011/02/01
TI – The role of natural climatic variation in perturbing the observed global mean temperature trend
JO – Climate Dynamics
SP – 509
EP – 521
VL – 36
IS – 3
AB – Controversy continues to prevail concerning the reality of anthropogenically-induced climatic warming. One of the principal issues is the cause of the hiatus in the current global warming trend. There appears to be a widely held view that climatic change warming should exhibit an inexorable upwards trend, a view that implies there is no longer any input by climatic variability in the existing climatic system. The relative roles of climatic change and climatic variability are examined here using the same coupled global climatic model. For the former, the model is run using a specified CO2 growth scenario, while the latter consisted of a multi-millennial simulation where any climatic variability was attributable solely to internal processes within the climatic system. It is shown that internal climatic variability can produce global mean surface temperature anomalies of ±0.25 K and sustained positive and negative anomalies sufficient to account for the anomalous warming of the 1940s as well as the present hiatus in the observed global warming. The characteristics of the internally-induced negative temperature anomalies are such that if this internal natural variability is the cause of the observed hiatus, then a resumption of the observed global warming trend is to be expected within the next few years.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-010-0799-x
DO – 10.1007/s00382-010-0799-x
ID – Hunt2011
ER –

NR – 18
TY – JOUR
AU – Risbey, James S.
AU – Lewandowsky, Stephan
AU – Langlais, Clothilde
AU – Monselesan, Didier P.
AU – O’Kane, Terence J.
AU – Oreskes, Naomi
TI – Well-estimated global surface warming in climate projections selected for ENSO phase
JA – Nature Climate Change
PY – 2014/07/20/online
VL – 4
SP – 835
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate2310
L3 – 10.1038/nclimate2310
M3 – Article
L3 –
AB – The question of how climate model projections have tracked the actual evolution of global mean surface air temperature is important in establishing the credibility of their projections. Some studies and the IPCC Fifth Assessment Report suggest that the recent 15-year period (1998–2012) provides evidence that models are overestimating current temperature evolution. Such comparisons are not evidence against model trends because they represent only one realization where the decadal natural variability component of the model climate is generally not in phase with observations. We present a more appropriate test of models where only those models with natural variability (represented by El Niño/Southern Oscillation) largely in phase with observations are selected from multi-model ensembles for comparison with observations. These tests show that climate models have provided good estimates of 15-year trends, including for recent periods and for Pacific spatial trend patterns.
ER –

NR – 19
TY – JOUR
AU – Lovejoy, S.
C8 – 2014GL060478
TI – Return periods of global climate fluctuations and the pause
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 13
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL060478
DO – 10.1002/2014GL060478
SP – 4704
EP – 4710
KW – global warming
KW – climate change
KW – anthropogenic warming
KW – statistical testing
KW – 0429 Climate dynamics
KW – 1616 Climate variability
PY – 2014
AB – An approach complementary to General Circulation Models (GCMs), using the anthropogenic CO2 radiative forcing as a linear surrogate for all anthropogenic forcings [Lovejoy, ], was recently developed for quantifying human impacts. Using preindustrial multiproxy series and scaling arguments, the probabilities of natural fluctuations at time lags up to 125?years were determined. The hypothesis that the industrial epoch warming was a giant natural fluctuation was rejected with 99.9% confidence. In this paper, this method is extended to the determination of event return times. Over the period 1880–2013, the largest 32?year event is expected to be 0.47?K, effectively explaining the postwar cooling (amplitude 0.42–0.47?K). Similarly, the “pause” since 1998 (0.28–0.37?K) has a return period of 20–50?years (not so unusual). It is nearly cancelled by the pre-pause warming event (1992–1998, return period 30–40?years); the pause is no more than natural variability.
ER –

NR – 20
TY – JOUR
AU – Guemas, Virginie
AU – Doblas-Reyes, Francisco J.
AU – Andreu-Burillo, Isabel
AU – Asif, Muhammad
TI – Retrospective prediction of the global warming slowdown in the past decade
JA – Nature Climate Change
PY – 2013/04/07/online
VL – 3
SP – 649
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate1863
L3 – 10.1038/nclimate1863
M3 –
L3 – https://www.nature.com/articles/nclimate1863#supplementary-information
AB – Despite a sustained production of anthropogenic greenhouse gases, the Earth’s mean near-surface temperature paused its rise during the 2000–2010 period1. To explain such a pause, an increase in ocean heat uptake below the superficial ocean layer2,3 has been proposed to overcompensate for the Earth’s heat storage. Contributions have also been suggested from the deep prolonged solar minimum4, the stratospheric water vapour5, the stratospheric6 and tropospheric aerosols7. However, a robust attribution of this warming slowdown has not been achievable up to now. Here we show successful retrospective predictions of this warming slowdown up to 5 years ahead, the analysis of which allows us to attribute the onset of this slowdown to an increase in ocean heat uptake. Sensitivity experiments accounting only for the external radiative forcings do not reproduce the slowdown. The top-of-atmosphere net energy input remained in the [0.5–1]?W?m-2 interval during the past decade, which is successfully captured by our predictions. Most of this excess energy was absorbed in the top 700?m of the ocean at the onset of the warming pause, 65% of it in the tropical Pacific and Atlantic oceans. Our results hence point at the key role of the ocean heat uptake in the recent warming slowdown. The ability to predict retrospectively this slowdown not only strengthens our confidence in the robustness of our climate models, but also enhances the socio-economic relevance of operational decadal climate predictions.
ER –

NR – 21
TY – JOUR
AU – Trenberth, Kevin E.
AU – Fasullo, John T.
TI – An apparent hiatus in global warming?
JO – Earth’s Future
JA – Earth’s Future
VL – 1
IS – 1
PB – Wiley Periodicals, Inc.
SN – 2328-4277
UR – http://dx.doi.org/10.1002/2013EF000165
DO – 10.1002/2013EF000165
SP – 19
EP – 32
KW – ENSO
KW – Pacific Decadal Oscillation
KW – global warming
KW – energy imbalance
KW – global temperatures
KW – 1620 Climate dynamics
KW – 1616 Climate variability
KW – 1635 Oceans
KW – 3305 Climate change and variability
KW – 3339 Ocean/atmosphere interactions
PY – 2013
AB – Global warming first became evident beyond the bounds of natural variability in the 1970s, but increases in global mean surface temperatures have stalled in the 2000s. Increases in atmospheric greenhouse gases, notably carbon dioxide, create an energy imbalance at the top-of-atmosphere (TOA) even as the planet warms to adjust to this imbalance, which is estimated to be 0.5–1?W?m-2 over the 2000s. Annual global fluctuations in TOA energy of up to 0.2?W?m-2 occur from natural variations in clouds, aerosols, and changes in the Sun. At times of major volcanic eruptions the effects can be much larger. Yet global mean surface temperatures fluctuate much more than these can account for. An energy imbalance is manifested not just as surface atmospheric or ground warming but also as melting sea and land ice, and heating of the oceans. More than 90% of the heat goes into the oceans and, with melting land ice, causes sea level to rise. For the past decade, more than 30% of the heat has apparently penetrated below 700?m depth that is traceable to changes in surface winds mainly over the Pacific in association with a switch to a negative phase of the Pacific Decadal Oscillation (PDO) in 1999. Surface warming was much more in evidence during the 1976–1998 positive phase of the PDO, suggesting that natural decadal variability modulates the rate of change of global surface temperatures while sea-level rise is more relentless. Global warming has not stopped; it is merely manifested in different ways.
ER –

NR – 22
TY – JOUR
AU – Meehl, Gerald A.
AU – Teng, Haiyan
AU – Arblaster, Julie M.
TI – Climate model simulations of the observed early-2000s hiatus of global warming
JA – Nature Climate Change
PY – 2014/09/07/online
VL – 4
SP – 898
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate2357
L3 – 10.1038/nclimate2357
M3 –
L3 – https://www.nature.com/articles/nclimate2357#supplementary-information
AB – The slowdown in the rate of global warming in the early 2000s is not evident in the multi-model ensemble average of traditional climate change projection simulations1. However, a number of individual ensemble members from that set of models successfully simulate the early-2000s hiatus when naturally-occurring climate variability involving the Interdecadal Pacific Oscillation (IPO) coincided, by chance, with the observed negative phase of the IPO that contributed to the early-2000s hiatus. If the recent methodology of initialized decadal climate prediction could have been applied in the mid-1990s using the Coupled Model Intercomparison Project Phase 5 multi-models, both the negative phase of the IPO in the early 2000s as well as the hiatus could have been simulated, with the multi-model average performing better than most of the individual models. The loss of predictive skill for six initial years before the mid-1990s points to the need for consistent hindcast skill to establish reliability of an operational decadal climate prediction system.
ER –

NR – 23
TY – JOUR
AU – Allan, Richard P.
AU – Liu, Chunlei
AU – Loeb, Norman G.
AU – Palmer, Matthew D.
AU – Roberts, Malcolm
AU – Smith, Doug
AU – Vidale, Pier-Luigi
TI – Changes in global net radiative imbalance 1985–2012
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 15
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL060962
DO – 10.1002/2014GL060962
SP – 5588
EP – 5597
KW – radiative flux
KW – climate variability
KW – satellite data
KW – climate model
KW – energy balance
KW – temperature
KW – 1616 Climate variability
KW – 1610 Atmosphere
KW – 1626 Global climate models
KW – 1635 Oceans
KW – 1640 Remote sensing
PY – 2014
AB – Combining satellite data, atmospheric reanalyses, and climate model simulations, variability in the net downward radiative flux imbalance at the top of Earth’s atmosphere (N) is reconstructed and linked to recent climate change. Over the 1985–1999 period mean N (0.34 ± 0.67?Wm-2) is lower than for the 2000–2012 period (0.62 ± 0.43?Wm-2, uncertainties at 90% confidence level) despite the slower rate of surface temperature rise since 2000. While the precise magnitude of N remains uncertain, the reconstruction captures interannual variability which is dominated by the eruption of Mount Pinatubo in 1991 and the El Niño Southern Oscillation. Monthly deseasonalized interannual variability in N generated by an ensemble of nine climate model simulations using prescribed sea surface temperature and radiative forcings and from the satellite-based reconstruction is significantly correlated (r~0.6) over the 1985–2012 period.
ER –

NR – 24
TY – JOUR
AU – Watanabe, Masahiro
AU – Shiogama, Hideo
AU – Tatebe, Hiroaki
AU – Hayashi, Michiya
AU – Ishii, Masayoshi
AU – Kimoto, Masahide
TI – Contribution of natural decadal variability to global warming acceleration and hiatus
JA – Nature Climate Change
PY – 2014/08/31/online
VL – 4
SP – 893
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate2355
L3 – 10.1038/nclimate2355
M3 –
L3 – https://www.nature.com/articles/nclimate2355#supplementary-information
AB – Reasons for the apparent pause in the rise of global-mean surface air temperature (SAT) after the turn of the century has been a mystery, undermining confidence in climate projections1,2,3. Recent climate model simulations indicate this warming hiatus originated from eastern equatorial Pacific cooling4 associated with strengthening of trade winds5. Using a climate model that overrides tropical wind stress anomalies with observations for 1958–2012, we show that decadal-mean anomalies of global SAT referenced to the period 1961–1990 are changed by 0.11, 0.13 and -0.11 °C in the 1980s, 1990s and 2000s, respectively, without variation in human-induced radiative forcing. They account for about 47%, 38% and 27% of the respective temperature change. The dominant wind stress variability consistent with this warming/cooling represents the deceleration/acceleration of the Pacific trade winds, which can be robustly reproduced by atmospheric model simulations forced by observed sea surface temperature excluding anthropogenic warming components. Results indicate that inherent decadal climate variability contributes considerably to the observed global-mean SAT time series, but that its influence on decadal-mean SAT has gradually decreased relative to the rising anthropogenic warming signal.
ER –

NR – 25
TY – JOUR
AU – Meehl, Gerald A.
AU – Teng, Haiyan
C8 – 2014GL059256
TI – CMIP5 multi-model hindcasts for the mid-1970s shift and early 2000s hiatus and predictions for 2016–2035
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 5
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL059256
DO – 10.1002/2014GL059256
SP – 1711
EP – 1716
KW – decadal prediction
KW – mid-1970s shift
KW – early-2000s hiatus
KW – 1616 Climate variability
KW – 1620 Climate dynamics
KW – 1626 Global climate models
PY – 2014
AB – Compared to uninitialized climate change projections, a multi-model ensemble from the CMIP5 10?year decadal prediction experiments produces more warming during the mid-1970s climate shift and less warming in the early 2000s hiatus in both the tropical Indo-Pacific region and globally averaged surface air temperature (TAS) in closer agreement with observations. Assuming bias in TAS has stabilized in the 10?year predictions, after bias adjustment, TAS anomalies for the 2016–2035 period in the 30?year predictions initialized in 2006 are about 16% less than the uninitialized projections. One contributing factor for the improved climate simulation is the bias adjustment, which corrects the models’ systematic errors and higher-than-observed decadal warming trend. Another important factor is the initialization with observations which constrains the ocean such that the starting points of the initialized simulations are close to the observed initial states.
ER –

NR – 26
TY – JOUR
AU – Watanabe, Masahiro
AU – Kamae, Youichi
AU – Yoshimori, Masakazu
AU – Oka, Akira
AU – Sato, Makiko
AU – Ishii, Masayoshi
AU – Mochizuki, Takashi
AU – Kimoto, Masahide
TI – Strengthening of ocean heat uptake efficiency associated with the recent climate hiatus
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 40
IS – 12
SN – 1944-8007
UR – http://dx.doi.org/10.1002/grl.50541
DO – 10.1002/grl.50541
SP – 3175
EP – 3179
KW – climate hiatus
KW – ocean heat uptake
KW – GCM
KW – surface temperature
KW – energy budget
KW – 1626 Global climate models
KW – 1616 Climate variability
KW – 1635 Oceans
KW – 1620 Climate dynamics
PY – 2013
AB – The rate of increase of global-mean surface air temperature (SATg) has apparently slowed during the last decade. We investigated the extent to which state-of-the-art general circulation models (GCMs) can capture this hiatus period by using multimodel ensembles of historical climate simulations. While the SATg linear trend for the last decade is not captured by their ensemble means regardless of differences in model generation and external forcing, it is barely represented by an 11-member ensemble of a GCM, suggesting an internal origin of the hiatus associated with active heat uptake by the oceans. Besides, we found opposite changes in ocean heat uptake efficiency (?), weakening in models and strengthening in nature, which explain why the models tend to overestimate the SATg trend. The weakening of ? commonly found in GCMs seems to be an inevitable response of the climate system to global warming, suggesting the recovery from hiatus in coming decades.
ER –

NR – 27
TY – JOUR
T1 – Externally Forced and Internally Generated Decadal Climate Variability Associated with the Interdecadal Pacific Oscillation
AU – Meehl, Gerald A.
AU – Hu, Aixue
AU – Arblaster, Julie M.
AU – Fasullo, John
AU – Trenberth, Kevin E.
Y1 – 2013/04/08
PY – 2013
DA – 2013/09/01
N1 – doi: 10.1175/JCLI-D-12-00548.1
DO – 10.1175/JCLI-D-12-00548.1
T2 – Journal of Climate
JF – Journal of Climate
JO – J. Climate
SP – 7298
EP – 7310
VL – 26
IS – 18
PB – American Meteorological Society
N2 – AbstractGlobally averaged surface air temperatures in some decades show rapid increases (accelerated warming decades), and in other decades there is no warming trend (hiatus decades). A previous study showed that the net energy imbalance at the top of the atmosphere of about 1 W m?2 is associated with greater increases of deep ocean heat content below 750 m during the hiatus decades, while there is little globally averaged surface temperature increase or warming in the upper ocean layers. Here the authors examine processes involved with accelerated warming decades and address the relative roles of external forcing from increasing greenhouse gases and internally generated decadal climate variability associated with interdecadal Pacific oscillation (IPO). Model results from the Community Climate System Model, version 4 (CCSM4), show that accelerated warming decades are characterized by rapid warming of globally averaged surface air temperature, greater increases of heat content in the upper ocean layers, and less heat content increase in the deep ocean, opposite to the hiatus decades. In addition to contributions from processes potentially linked to Antarctic Bottom Water (AABW) formation and the Atlantic meridional overturning circulation (AMOC), the positive phase of the IPO, adding to the response to external forcing, is usually associated with accelerated warming decades. Conversely, hiatus decades typically occur with the negative phase of the IPO, when warming from the external forcing is overwhelmed by internally generated cooling in the tropical Pacific. Internally generated hiatus periods of up to 15 years with zero global warming trend are present in the future climate simulations. This suggests that there is a chance that the current observed hiatus could extend for several more years.
AB – AbstractGlobally averaged surface air temperatures in some decades show rapid increases (accelerated warming decades), and in other decades there is no warming trend (hiatus decades). A previous study showed that the net energy imbalance at the top of the atmosphere of about 1 W m?2 is associated with greater increases of deep ocean heat content below 750 m during the hiatus decades, while there is little globally averaged surface temperature increase or warming in the upper ocean layers. Here the authors examine processes involved with accelerated warming decades and address the relative roles of external forcing from increasing greenhouse gases and internally generated decadal climate variability associated with interdecadal Pacific oscillation (IPO). Model results from the Community Climate System Model, version 4 (CCSM4), show that accelerated warming decades are characterized by rapid warming of globally averaged surface air temperature, greater increases of heat content in the upper ocean layers, and less heat content increase in the deep ocean, opposite to the hiatus decades. In addition to contributions from processes potentially linked to Antarctic Bottom Water (AABW) formation and the Atlantic meridional overturning circulation (AMOC), the positive phase of the IPO, adding to the response to external forcing, is usually associated with accelerated warming decades. Conversely, hiatus decades typically occur with the negative phase of the IPO, when warming from the external forcing is overwhelmed by internally generated cooling in the tropical Pacific. Internally generated hiatus periods of up to 15 years with zero global warming trend are present in the future climate simulations. This suggests that there is a chance that the current observed hiatus could extend for several more years.
SN – 0894-8755
M3 – doi: 10.1175/JCLI-D-12-00548.1
UR – https://doi.org/10.1175/JCLI-D-12-00548.1
Y2 – 2017/12/12
ER –

NR – 28
TY – JOUR
AU – Meehl, Gerald A.
AU – Arblaster, Julie M.
AU – Fasullo, John T.
AU – Hu, Aixue
AU – Trenberth, Kevin E.
TI – Model-based evidence of deep-ocean heat uptake during surface-temperature hiatus periods
JA – Nature Climate Change
PY – 2011/09/18/online
VL – 1
SP – 360
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate1229
L3 – 10.1038/nclimate1229
M3 –
L3 – https://www.nature.com/articles/nclimate1229#supplementary-information
AB – There have been decades, such as 2000–2009, when the observed globally averaged surface-temperature time series shows little increase or even a slightly negative trend1 (a hiatus period). However, the observed energy imbalance at the top-of-atmosphere for this recent decade indicates that a net energy flux into the climate system of about 1?W?m-2 (refs 2, 3) should be producing warming somewhere in the system4,5. Here we analyse twenty-first-century climate-model simulations that maintain a consistent radiative imbalance at the top-of-atmosphere of about 1?W?m-2 as observed for the past decade. Eight decades with a slightly negative global mean surface-temperature trend show that the ocean above 300?m takes up significantly less heat whereas the ocean below 300?m takes up significantly more, compared with non-hiatus decades. The model provides a plausible depiction of processes in the climate system causing the hiatus periods, and indicates that a hiatus period is a relatively common climate phenomenon and may be linked to La Niña-like conditions.
ER –

NR – 29
TY – JOUR
T1 – Contributions of Stratospheric Water Vapor to Decadal Changes in the Rate of Global Warming
JF – Science
JO – Science
SP – 1219
LP – 1223
M3 – 10.1126/science.1182488
VL – 327
IS – 5970
AU – Solomon, Susan
AU – Rosenlof, Karen H.
AU – Portmann, Robert W.
AU – Daniel, John S.
AU – Davis, Sean M.
AU – Sanford, Todd J.
AU – Plattner, Gian-Kasper
Y1 – 2010/03/05
UR – http://science.sciencemag.org/content/327/5970/1219.abstract
N2 – Stratospheric water vapor concentrations decreased by about 10% after the year 2000. Here we show that this acted to slow the rate of increase in global surface temperature over 2000–2009 by about 25% compared to that which would have occurred due only to carbon dioxide and other greenhouse gases. More limited data suggest that stratospheric water vapor probably increased between 1980 and 2000, which would have enhanced the decadal rate of surface warming during the 1990s by about 30% as compared to estimates neglecting this change. These findings show that stratospheric water vapor is an important driver of decadal global surface climate change.
ER –

NR – 30
TY – JOUR
AU – England, Matthew H.
AU – McGregor, Shayne
AU – Spence, Paul
AU – Meehl, Gerald A.
AU – Timmermann, Axel
AU – Cai, Wenju
AU – Gupta, Alex Sen
AU – McPhaden, Michael J.
AU – Purich, Ariaan
AU – Santoso, Agus
TI – Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus
JA – Nature Climate Change
PY – 2014/02/09/online
VL – 4
SP – 222
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate2106
L3 – 10.1038/nclimate2106
M3 – Article
L3 – https://www.nature.com/articles/nclimate2106#supplementary-information
AB – Despite ongoing increases in atmospheric greenhouse gases, the Earth’s global average surface air temperature has remained more or less steady since 2001. A variety of mechanisms have been proposed to account for this slowdown in surface warming. A key component of the global hiatus that has been identified is cool eastern Pacific sea surface temperature, but it is unclear how the ocean has remained relatively cool there in spite of ongoing increases in radiative forcing. Here we show that a pronounced strengthening in Pacific trade winds over the past two decades—unprecedented in observations/reanalysis data and not captured by climate models—is sufficient to account for the cooling of the tropical Pacific and a substantial slowdown in surface warming through increased subsurface ocean heat uptake. The extra uptake has come about through increased subduction in the Pacific shallow overturning cells, enhancing heat convergence in the equatorial thermocline. At the same time, the accelerated trade winds have increased equatorial upwelling in the central and eastern Pacific, lowering sea surface temperature there, which drives further cooling in other regions. The net effect of these anomalous winds is a cooling in the 2012 global average surface air temperature of 0.1–0.2 °C, which can account for much of the hiatus in surface warming observed since 2001. This hiatus could persist for much of the present decade if the trade wind trends continue, however rapid warming is expected to resume once the anomalous wind trends abate.
ER –

NR – 31
TY – JOUR
AU – Drijfhout, S. S.
AU – Blaker, A. T.
AU – Josey, S. A.
AU – Nurser, A. J. G.
AU – Sinha, B.
AU – Balmaseda, M. A.
TI – Surface warming hiatus caused by increased heat uptake across multiple ocean basins
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 22
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL061456
DO – 10.1002/2014GL061456
SP – 7868
EP – 7874
KW – climate hiatus
KW – 1699 General or miscellaneous
KW – 1616 Climate variability
KW – 4599 General or miscellaneous
KW – 4572 Upper ocean and mixed layer processes
KW – 4532 General circulation
PY – 2014
AB – The first decade of the 21st century was characterized by a hiatus in global surface warming. Using ocean model hindcasts and reanalyses we show that heat uptake between the 1990s and 2000s increased by 0.7 ± 0.3W?m-2. Approximately 30% of the increase is associated with colder sea surface temperatures in the eastern Pacific. Other basins contribute via reduced heat loss to the atmosphere, in particular, the Southern and subtropical Indian Oceans (30%) and the subpolar North Atlantic (40%). A different mechanism is important at longer timescales (1960s–present) over which the Southern Annular Mode trended upward. In this period, increased ocean heat uptake has largely arisen from reduced heat loss associated with reduced winds over the Agulhas Return Current and southward displacement of Southern Ocean westerlies.
ER –

NR – 32
TY – JOUR
T1 – Varying planetary heat sink led to global-warming slowdown and acceleration
JF – Science
JO – Science
SP – 897
LP – 903
M3 – 10.1126/science.1254937
VL – 345
IS – 6199
AU – Chen, Xianyao
AU – Tung, Ka-Kit
Y1 – 2014/08/22
UR – http://science.sciencemag.org/content/345/6199/897.abstract
N2 – Global warming seems to have paused over the past 15 years while the deep ocean takes the heat instead. The thermal capacity of the oceans far exceeds that of the atmosphere, so the oceans can store up to 90% of the heat buildup caused by increased concentrations of greenhouse gases such as carbon dioxide. Chen and Tung used observational data to trace the pathways of recent ocean heating. They conclude that the deep Atlantic and Southern Oceans, but not the Pacific, have absorbed the excess heat that would otherwise have fueled continued warming.Science, this issue p. 897 A vacillating global heat sink at intermediate ocean depths is associated with different climate regimes of surface warming under anthropogenic forcing: The latter part of the 20th century saw rapid global warming as more heat stayed near the surface. In the 21st century, surface warming slowed as more heat moved into deeper oceans. In situ and reanalyzed data are used to trace the pathways of ocean heat uptake. In addition to the shallow La Niña–like patterns in the Pacific that were the previous focus, we found that the slowdown is mainly caused by heat transported to deeper layers in the Atlantic and the Southern oceans, initiated by a recurrent salinity anomaly in the subpolar North Atlantic. Cooling periods associated with the latter deeper heat-sequestration mechanism historically lasted 20 to 35 years.
ER –

NR – 33
TY – JOUR
AU – Kosaka, Yu
AU – Xie, Shang-Ping
TI – Recent global-warming hiatus tied to equatorial Pacific surface cooling
JA – Nature
PY – 2013/08/28/online
VL – 501
SP – 403
EP –
PB – Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
SN –
UR – http://dx.doi.org/10.1038/nature12534
L3 – 10.1038/nature12534
M3 –
L3 –
AB – Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century1,2, challenging the prevailing view that anthropogenic forcing causes climate warming. Various mechanisms have been proposed for this hiatus in global warming3,4,5,6, but their relative importance has not been quantified, hampering observational estimates of climate sensitivity. Here we show that accounting for recent cooling in the eastern equatorial Pacific reconciles climate simulations and observations. We present a novel method of uncovering mechanisms for global temperature change by prescribing, in addition to radiative forcing, the observed history of sea surface temperature over the central to eastern tropical Pacific in a climate model. Although the surface temperature prescription is limited to only 8.2% of the global surface, our model reproduces the annual-mean global temperature remarkably well with correlation coefficient r = 0.97 for 1970–2012 (which includes the current hiatus and a period of accelerated global warming). Moreover, our simulation captures major seasonal and regional characteristics of the hiatus, including the intensified Walker circulation, the winter cooling in northwestern North America and the prolonged drought in the southern USA. Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Niña-like decadal cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas increase.
ER –

NR – 34
TY – JOUR
T1 – Application of the Singular Spectrum Analysis Technique to Study the Recent Hiatus on the Global Surface Temperature Record
A1 – Macias, Diego
A1 – Stips, Adolf
A1 – Garcia-Gorriz, Elisa
Y1 – 2014/09/10
N2 – Global surface temperature has been increasing since the beginning of the 20th century but with a highly variable warming rate, and the alternation of rapid warming periods with ‘hiatus’ decades is a constant throughout the series. The superimposition of a secular warming trend with natural multidecadal variability is the most accepted explanation for such a pattern. Since the start of the 21st century, the surface global mean temperature has not risen at the same rate as the top-of-atmosphere radiative energy input or greenhouse gas emissions, provoking scientific and social interest in determining the causes of this apparent discrepancy. Multidecadal natural variability is the most commonly proposed cause for the present hiatus period. Here, we analyze the HadCRUT4 surface temperature database with spectral techniques to separate a multidecadal oscillation (MDV) from a secular trend (ST). Both signals combined account for nearly 88% of the total variability of the temperature series showing the main acceleration/deceleration periods already described elsewhere. Three stalling periods with very little warming could be found within the series, from 1878 to 1907, from 1945 to 1969 and from 2001 to the end of the series, all of them coincided with a cooling phase of the MDV. Henceforth, MDV seems to be the main cause of the different hiatus periods shown by the global surface temperature records. However, and contrary to the two previous events, during the current hiatus period, the ST shows a strong fluctuation on the warming rate, with a large acceleration (0.0085°C year-1 to 0.017°C year-1) during 1992–2001 and a sharp deceleration (0.017°C year-1 to 0.003°C year-1) from 2002 onwards. This is the first time in the observational record that the ST shows such variability, so determining the causes and consequences of this change of behavior needs to be addressed by the scientific community.
JF – PLOS ONE
JA – PLOS ONE
VL – 9
IS – 9
UR – https://doi.org/10.1371/journal.pone.0107222
SP – e107222
EP –
PB – Public Library of Science
M3 – doi:10.1371/journal.pone.0107222
ER –

NR – 35
TY – JOUR
AU – Haywood, Jim M.
AU – Jones, Andy
AU – Jones, Gareth S.
TI – The impact of volcanic eruptions in the period 2000–2013 on global mean temperature trends evaluated in the HadGEM2-ES climate model
JO – Atmospheric Science Letters
JA – Atmos. Sci. Lett.
VL – 15
IS – 2
PB – John Wiley & Sons, Ltd
SN – 1530-261X
UR – http://dx.doi.org/10.1002/asl2.471
DO – 10.1002/asl2.471
SP – 92
EP – 96
KW – stratospheric aerosol
KW – volcanic eruptions
KW – climate
KW – global warming
PY – 2014
AB – The slow-down in global warming over the last decade has lead to significant debate about whether the causes are of natural or anthropogenic origin. Using an ensemble of HadGEM2-ES coupled climate model simulations we investigate the impact of overlooked modest volcanic eruptions. We deduce a global mean cooling of around -0.02 to -0.03?K over the period 2008–2012. Thus while these eruptions do cause a cooling of the Earth and may therefore contribute to the slow-down in global warming, they do not appear to be the sole or primary cause.
ER –

NR – 36
TY – JOUR
AU – Goddard, Lisa
TI – Heat hide and seek
JA – Nature Climate Change
PY – 2014/02/26/online
VL – 4
SP – 158
EP –
PB – Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
SN –
UR – http://dx.doi.org/10.1038/nclimate2155
L3 – 10.1038/nclimate2155
M3 –
L3 –
AB – Natural variability can explain fluctuations in surface temperatures but can it account for the current slowdown in warming?
ER –

NR – 37
TY – JOUR
AU – Lin, I.-I.
AU – Pun, Iam-Fei
AU – Lien, Chun-Chi
C8 – 2014GL061281
TI – “Category-6” supertyphoon Haiyan in global warming hiatus: Contribution from subsurface ocean warming
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 23
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL061281
DO – 10.1002/2014GL061281
SP – 8547
EP – 8553
KW – Supertyphoon
KW – Haiyan
KW – Global Warming
KW – Hiatus
KW – 1616 Climate variability
KW – 4504 Air/sea interactions
PY – 2014
AB – With the extra-ordinary intensity of 170 kts, supertyphoon Haiyan devastated the Philippines in November 2013. This intensity is among the highest ever observed for tropical cyclones (TCs) globally, 35 kts well above the threshold (135kts) of the existing highest category of 5. Though there is speculation to associate global warming with such intensity, existing research indicate that we have been in a warming hiatus period, with the hiatus attributed to the La Niña-like multi-decadal phenomenon. It is thus intriguing to understand why Haiyan can occur during hiatus. It is suggested that as the western Pacific manifestation of the La Niña-like phenomenon is to pile up warm subsurface water to the west, the western North Pacific experienced evident subsurface warming and created a very favorable ocean pre-condition for Haiyan. Together with its fast traveling speed, the air-sea flux supply was 158% as compared to normal for intensification.
ER –

NR – 38
TY – JOUR
AU – Fyfe, John C.
AU – Gillett, Nathan P.
AU – Zwiers, Francis W.
TI – Overestimated global warming over the past 20 years
JA – Nature Climate Change
PY – 2013/08/28/online
VL – 3
SP – 767
EP –
PB – Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
SN –
UR – http://dx.doi.org/10.1038/nclimate1972
L3 – 10.1038/nclimate1972
M3 –
L3 – https://www.nature.com/articles/nclimate1972#supplementary-information
AB – Recent observed global warming is significantly less than that simulated by climate models. This difference might be explained by some combination of errors in external forcing, model response and internal climate variability.
ER –

NR – 39
TY – JOUR
AU – Crowley, Thomas J.
AU – Obrochta, Stephen P.
AU – Liu, Junhua
TI – Recent global temperature “plateau” in the context of a new proxy reconstruction
JO – Earth’s Future
JA – Earth’s Future
VL – 2
IS – 5
PB – Wiley Periodicals, Inc.
SN – 2328-4277
UR – http://dx.doi.org/10.1002/2013EF000216
DO – 10.1002/2013EF000216
SP – 281
EP – 294
KW – Global Warming
KW – Temperature Reconstruction
KW – Natural Variability
PY – 2014
AB – Stable global temperatures of the last 10–15 years have been a topic of considerable discussion. A new proxy extension of the global temperature record enables better placement of this feature in a longer historical perspective. The fixed-grid composite covers the interval 1801–1984, with an extension to 1782, and anchors the global temperature record in the last major cold interval of the Little Ice Age, when carbon dioxide concentration was at preanthropogenic levels. Except for greater and longer cooling (approximately twice the length of Pinatubo) associated with the Tambora eruption, the proxy agrees with the most widely cited previous assessment of global temperature over this interval, lending more confidence to a centennial extension of the global temperature record. The proxy correlation is as high as 0.83 for the interval 1907–1984 (df?=?8, p?=?0.001), with the 21st century 1.0°C?±?0.2°C warmer than the nonvolcanic base state. This remarkable linearity requires a clear theoretical understanding as to how an exceedingly complex system can, on the global average, behave in such a simple way. Removal of the linear radiatively forced component from the global temperature record yields an estimate of natural variability for the last 230 years and indicates no unusual natural variability during the recent 10–15 years. Based on the estimate of unforced variability over the last 170 years, there is about a 40% chance of continued “natural cooling” over the next few years, with about a 10% chance of cooling persisting into the next decade.
ER –

NR – 40
TY – JOUR
AU – Trenberth, Kevin E.
AU – Fasullo, John T.
AU – Branstator, Grant
AU – Phillips, Adam S.
TI – Seasonal aspects of the recent pause in surface warming
JA – Nature Climate Change
PY – 2014/08/17/online
VL – 4
SP – 911
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate2341
L3 – 10.1038/nclimate2341
M3 – Article
L3 – https://www.nature.com/articles/nclimate2341#supplementary-information
AB – Factors involved in the recent pause in the rise of global mean temperatures are examined seasonally. For 1999 to 2012, the hiatus in surface warming is mainly evident in the central and eastern Pacific. It is manifested as strong anomalous easterly trade winds, distinctive sea-level pressure patterns, and large rainfall anomalies in the Pacific, which resemble the Pacific Decadal Oscillation (PDO). These features are accompanied by upper tropospheric teleconnection wave patterns that extend throughout the Pacific, to polar regions, and into the Atlantic. The extratropical features are particularly strong during winter. By using an idealized heating to force a comprehensive atmospheric model, the large negative anomalous latent heating associated with the observed deficit in central tropical Pacific rainfall is shown to be mainly responsible for the global quasi-stationary waves in the upper troposphere. The wave patterns in turn created persistent regional climate anomalies, increasing the odds of cold winters in Europe. Hence, tropical Pacific forcing of the atmosphere such as that associated with a negative phase of the PDO produces many of the pronounced atmospheric circulation anomalies observed globally during the hiatus.
ER –

NR – 41
TY – JOUR
AU – Estrada, Francisco
AU – Perron, Pierre
AU – Martínez-López, Benjamín
TI – Statistically derived contributions of diverse human influences to twentieth-century temperature changes
JA – Nature Geoscience
PY – 2013/11/10/online
VL – 6
SP – 1050
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/ngeo1999
L3 – 10.1038/ngeo1999
M3 – Article
L3 – https://www.nature.com/articles/ngeo1999#supplementary-information
AB – The warming of the climate system is unequivocal as evidenced by an increase in global temperatures by 0.8?°C over the past century. However, the attribution of the observed warming to human activities remains less clear, particularly because of the apparent slow-down in warming since the late 1990s. Here we analyse radiative forcing and temperature time series with state-of-the-art statistical methods to address this question without climate model simulations. We show that long-term trends in total radiative forcing and temperatures have largely been determined by atmospheric greenhouse gas concentrations, and modulated by other radiative factors. We identify a pronounced increase in the growth rates of both temperatures and radiative forcing around 1960, which marks the onset of sustained global warming. Our analyses also reveal a contribution of human interventions to two periods when global warming slowed down. Our statistical analysis suggests that the reduction in the emissions of ozone-depleting substances under the Montreal Protocol, as well as a reduction in methane emissions, contributed to the lower rate of warming since the 1990s. Furthermore, we identify a contribution from the two world wars and the Great Depression to the documented cooling in the mid-twentieth century, through lower carbon dioxide emissions. We conclude that reductions in greenhouse gas emissions are effective in slowing the rate of warming in the short term.
ER –

NR – 42
TY – JOUR
AU – Ridley, D. A.
AU – Solomon, S.
AU – Barnes, J. E.
AU – Burlakov, V. D.
AU – Deshler, T.
AU – Dolgii, S. I.
AU – Herber, A. B.
AU – Nagai, T.
AU – Neely, R. R.
AU – Nevzorov, A. V.
AU – Ritter, C.
AU – Sakai, T.
AU – Santer, B. D.
AU – Sato, M.
AU – Schmidt, A.
AU – Uchino, O.
AU – Vernier, J. P.
C8 – 2014GL061541
TI – Total volcanic stratospheric aerosol optical depths and implications for global climate change
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 22
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL061541
DO – 10.1002/2014GL061541
SP – 7763
EP – 7769
KW – volcanic aerosol
KW – forcing uncertainty
KW – warming hiatus
KW – AERONET retrieval
KW – lower stratospheric AOD
KW – stratospheric aerosol
KW – 0370 Volcanic effects
KW – 0305 Aerosols and particles
KW – 3305 Climate change and variability
KW – 3359 Radiative processes
KW – 3360 Remote sensing
PY – 2014
AB – Understanding the cooling effect of recent volcanoes is of particular interest in the context of the post-2000 slowing of the rate of global warming. Satellite observations of aerosol optical depth above 15?km have demonstrated that small-magnitude volcanic eruptions substantially perturb incoming solar radiation. Here we use lidar, Aerosol Robotic Network, and balloon-borne observations to provide evidence that currently available satellite databases neglect substantial amounts of volcanic aerosol between the tropopause and 15?km at middle to high latitudes and therefore underestimate total radiative forcing resulting from the recent eruptions. Incorporating these estimates into a simple climate model, we determine the global volcanic aerosol forcing since 2000 to be -0.19?±?0.09?Wm-2. This translates into an estimated global cooling of 0.05 to 0.12°C. We conclude that recent volcanic events are responsible for more post-2000 cooling than is implied by satellite databases that neglect volcanic aerosol effects below 15?km.
ER –

NR – 43
TY – JOUR
UR – http://stacks.iop.org/1748-9326/9/i=3/a=034016
T1 – Internal variability of Earth’s energy budget simulated by CMIP5 climate models
A1 – M D Palmer and D J McNeall
Y1 – 2014
SP – 034016
JF – Environmental Research Letters
VL – 9
IS – 3
SN – 1748-9326
DO – https://doi.org/10.1088/1748-9326/9/3/034016
N2 – We analyse a large number of multi-century pre-industrial control simulations from the fifth phase
of the Coupled Model Intercomparison Project (CMIP5) to investigate relationships between: net
top-of-atmosphere radiation (TOA), globally averaged surface temperature (GST), and globally
integrated ocean heat content (OHC) on decadal timescales. Consistent with previous studies, we find
that large trends (~0.3 K dec -1 ) in GST can arise from internal climate variability and that these
trends are generally an unreliable indicator of TOA over the same period. In contrast, trends in
total OHC explain 95% or more of the variance in TOA for two-thirds of the models analysed;
emphasizing the oceans’ role as Earth’s primary energy store. Correlation of trends in total system
energy (TE = time integrated TOA) against trends in OHC suggests that for most models the ocean
becomes the dominant term in the planetary energy budget on a timescale of about 12 months. In the
context of the recent pause in global surface temperature rise, we investigate the potential
importance of internal climate variability in both TOA and ocean heat rearrangement. The model
simulations suggest that both factors can account for O (0.1 W m -2 ) on decadal timescales and may
play an important role in the recently observed trends in GST and 0–700 m (and 0–1800 m) ocean heat
uptake.
ER –

NR – 44
TY – JOUR
AU – Lu, Jianhua
AU – Hu, Aixue
AU – Zeng, Zhen
C8 – 2014GL059908
TI – On the possible interaction between internal climate variability and forced climate change
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 8
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL059908
DO – 10.1002/2014GL059908
SP – 2962
EP – 2970
KW – climate variability
KW – forced climate change
KW – global warming hiatus
KW – Atlantic Multidecadal Variability (AMV)
KW – Pacific Decadal Oscillation (PDO)
KW – 1620 Climate dynamics
KW – 3305 Climate change and variability
KW – 3339 Ocean/atmosphere interactions
KW – 4513 Decadal ocean variability
PY – 2014
AB – The global warming hiatus does not necessarily mean a hiatus in anthropogenic greenhouse gas forcing and forced climate change (FCC). Here we show that both Atlantic Multidecadal Variability (AMV) and Pacific Decadal Oscillation (PDO) may cause fluctuations of the global mean surface air temperature (SAT) and hence alternately positive and negative trends on (inter)decadal time scales. However, the forced SAT change under a mean state due to greenhouse gas forcing does not depend on different phases of AMV and PDO, implying the effect of the FCC and internally generated climate variability can be linearly added up to the observed transient global mean SAT. On the other hand, the regional patterns of transient FCC do depend on the phases of the internal variability since the atmospheric and oceanic circulations can be affected by the different phases of the internal variability. Our results suggest a two-way interaction between internal variability and spatial patterns of FCC.
ER –

NR – 45
TY – JOUR
AU – McGregor, Shayne
AU – Timmermann, Axel
AU – Stuecker, Malte F.
AU – England, Matthew H.
AU – Merrifield, Mark
AU – Jin, Fei-Fei
AU – Chikamoto, Yoshimitsu
TI – Recent Walker circulation strengthening and Pacific cooling amplified by Atlantic warming
JA – Nature Climate Change
PY – 2014/08/03/online
VL – 4
SP – 888
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate2330
L3 – 10.1038/nclimate2330
M3 –
L3 – https://www.nature.com/articles/nclimate2330#supplementary-information
AB – An unprecedented strengthening of Pacific trade winds since the late 1990s (ref. 1) has caused widespread climate perturbations, including rapid sea-level rise in the western tropical Pacific2,3,4,5, strengthening of Indo-Pacific ocean currents6,7, and an increased uptake of heat in the equatorial Pacific thermocline1. The corresponding intensification of the atmospheric Walker circulation is also associated with sea surface cooling in the eastern Pacific, which has been identified as one of the contributors to the current pause in global surface warming1,8,9. In spite of recent progress in determining the climatic impacts of the Pacific trade wind acceleration, the cause of this pronounced trend in atmospheric circulation remains unknown. Here we analyse a series of climate model experiments along with observational data to show that the recent warming trend in Atlantic sea surface temperature and the corresponding trans-basin displacements of the main atmospheric pressure centres were key drivers of the observed Walker circulation intensification, eastern Pacific cooling, North American rainfall trends and western Pacific sea-level rise. Our study suggests that global surface warming has been partly offset by the Pacific climate response to enhanced Atlantic warming since the early 1990s.
ER –

NR – 46
TY – JOUR
T1 – An econometric analysis of global warming hiatus
AU – Furuoka, Fumitaka
Y1 – 2017/10/07
PY – 2017
DA – 2017/10/07
N1 – doi: 10.1080/13504851.2016.1270400
DO – 10.1080/13504851.2016.1270400
T2 – Applied Economics Letters
JF – Applied Economics Letters
JO – Applied Economics Letters
SP – 1241
EP – 1246
VL – 24
IS – 17
PB – Routledge
AB – ABSTRACTThere is an avid debate concerning the presence of a hiatus in global warming. Recognizing that this phenomenon has considerable economic implications, this study aims to make a threefold contribution to the climate econometrics literature. Firstly, it formulates a testable hypothesis; secondly, it proposes a systematic empirical procedure; thirdly, it performs the Bai?Perron test to detect the starting point of the global warming hiatus. The findings supported the existence of the global warming hiatus.
SN – 1350-4851
M3 – doi: 10.1080/13504851.2016.1270400
UR – https://doi.org/10.1080/13504851.2016.1270400
ER –

NR – 47
TY – JOUR
UR – http://stacks.iop.org/1748-9326/10/i=8/a=084002
T1 – Change points of global temperature
A1 – Niamh Cahill and Stefan Rahmstorf and Andrew C Parnell
Y1 – 2015
SP – 084002
JF – Environmental Research Letters
VL – 10
IS – 8
SN – 1748-9326
DO – https://doi.org/10.1088/1748-9326/10/8/084002
AB – We aim to address the question of whether or not there is a significant recent ‘hiatus’, ‘pause’ or
‘slowdown’ of global temperature rise. Using a statistical technique known as change point (CP)
analysis we identify the changes in four global temperature records and estimate the rates of
temperature rise before and after these changes occur. For each record the results indicate that
three CPs are enough to accurately capture the variability in the data with no evidence of any
detectable change in the global warming trend since ~1970. We conclude that the term ‘hiatus’ or
‘pause’ cannot be statistically justified.
ER –

NR – 49
TY – JOUR
TI – Detecting Warming Hiatus Periods in CMIP5 Climate Model Projections
JO – International Journal of Atmospheric Sciences
VL – 2016
PY – 2016
AU – Li, Tony W.
AU – Baker, Noel C.
DO – 10.1155/2016/9657659
UR – http://dx.doi.org/10.1155/2016/9657659
AB – The observed slow-down in the global-mean surface temperature (GST) warming from 1998 to 2012 has been called a “warming hiatus.” Certain climate models, operating under experiments which simulate warming by increasing radiative forcing, have been shown to reproduce periods which resemble the observed hiatus. The present study provides a comprehensive analysis of 38 CMIP5 climate models to provide further evidence that models produce warming hiatus periods during warming experiments. GST rates are simulated in each model for the 21st century using two experiments: a moderate warming scenario (RCP4.5) and high-end scenario (RCP8.5). Warming hiatus periods are identified in model simulations by detecting (1) =15-year periods lacking a statistically meaningful trend and (2) rapid changes in the GST rate which resemble the observed 1998–2012 hiatus. Under the RCP4.5 experiment, all tested models produce warming hiatus periods. However, once radiative forcing exceeds 5?W/m2—about 2°C GST increase—as simulated in the RCP8.5 experiment after 2050, nearly all models produce only positive warming trends. All models show evidence of rapid changes in the GST rate resembling the observed hiatus, showing that the climate variations associated with warming hiatus periods are still evident in the models, even under accelerated warming conditions.
ER –

NR – 50
TY – JOUR
AU – Cazenave, Anny
AU – Dieng, Habib-Boubacar
AU – Meyssignac, Benoit
AU – von Schuckmann, Karina
AU – Decharme, Bertrand
AU – Berthier, Etienne
TI – The rate of sea-level rise
JO – Nature Climate Change
VL – 4
IS – 5
SP – 358
EP – 361
PY – 2014
DO – 10.1038/nclimate2159
UR – http://dx.doi.org/10.1038/nclimate2159
AB – Present-day sea-level rise is a major indicator of climate change. Since the early 1990s, sea level rose at a mean rate of ~3.1 mm yr-1 (refs 2, 3). However, over the last decade a slowdown of this rate, of about 30%, has been recorded. It coincides with a plateau in Earth’s mean surface temperature evolution, known as the recent pause in warming. Here we present an analysis based on sea-level data from the altimetry record of the past ~20 years that separates interannual natural variability in sea level from the longer-term change probably related to anthropogenic global warming. The most prominent signature in the global mean sea level interannual variability is caused by El Niño–Southern Oscillation, through its impact on the global water cycle. We find that when correcting for interannual variability, the past decade’s slowdown of the global mean sea level disappears, leading to a similar rate of sea-level rise (of 3.3 ± 0.4 mm yr-1) during the first and second decade of the altimetry era. Our results confirm the need for quantifying and further removing from the climate records the short-term natural climate variability if one wants to extract the global warming signal.
ER –

NR – 51
TY – JOUR
AU – Lian, Tao
PY – 2017
DA – 2017/10/01
TI – Uncertainty in detecting trend: a new criterion and its applications to global SST
JO – Climate Dynamics
SP – 2881
EP – 2893
VL – 49
IS – 7
AB – In most parts of the global ocean, the magnitude of the long-term linear trend in sea surface temperature (SST) is much smaller than the amplitude of multi-scale internal variation. One can thus use a specific period in a much longer record to arbitrarily determine the sign of long-term trend, which is statistically significant, in regional SST. This could lead to a controversial conclusion on how global SST responded to the anthropogenic forcing in the recent history. In this study, the uncertainty in the linear trend due to multi-scale internal variation is theoretically investigated. It is found that the “estimated” trend will not change its sign only when its magnitude is greater than a theoretical threshold that scales the influence from the multi-scale internal variation. Otherwise, the sign of the “estimated” trend may depend on the period used. The new criterion is found to be superior over the existing methods when the de-trended time series is dominated by the oscillatory term. Applying this new criterion to a global SST reconstruction from 1881 to 2013 reveals that the influences from multi-scale internal variation on the sign of “estimated” linear trend cannot be excluded in most parts of the Pacific, the southern Indian Ocean and the northern Atlantic; therefore, the warming or/and cooling trends found in these regions cannot be interpreted as the consequences of anthropogenic forcing. It’s also suggested that the recent hiatus can be explained by combined uncertainty from internal variations at the interannual and decadal time scales.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-016-3483-y
DO – 10.1007/s00382-016-3483-y
ID – Lian2017
ER –

NR – 52
TY – JOUR
AU – Marotzke, Jochem
AU – Forster, Piers M.
TI – Forcing, feedback and internal variability in global temperature trends
JA – Nature
PY – 2015/01/28/online
VL – 517
SP – 565
EP –
PB – Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
SN –
UR – http://dx.doi.org/10.1038/nature14117
L3 – 10.1038/nature14117
M3 – Article
L3 –
AB – Most present-generation climate models simulate an increase in global-mean surface temperature (GMST) since 1998, whereas observations suggest a warming hiatus. It is unclear to what extent this mismatch is caused by incorrect model forcing, by incorrect model response to forcing or by random factors. Here we analyse simulations and observations of GMST from 1900 to 2012, and show that the distribution of simulated 15-year trends shows no systematic bias against the observations. Using a multiple regression approach that is physically motivated by surface energy balance, we isolate the impact of radiative forcing, climate feedback and ocean heat uptake on GMST—with the regression residual interpreted as internal variability—and assess all possible 15- and 62-year trends. The differences between simulated and observed trends are dominated by random internal variability over the shorter timescale and by variations in the radiative forcings used to drive models over the longer timescale. For either trend length, spread in simulated climate feedback leaves no traceable imprint on GMST trends or, consequently, on the difference between simulations and observations. The claim that climate models systematically overestimate the response to radiative forcing from increasing greenhouse gas concentrations therefore seems to be unfounded.
ER –

NR – 53
TY – JOUR
AU – Swanson, Kyle L.
AU – Tsonis, Anastasios A.
C8 – L06711
TI – Has the climate recently shifted?
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 36
IS – 6
SN – 1944-8007
UR – http://dx.doi.org/10.1029/2008GL037022
DO – 10.1029/2008GL037022
SP – n/a
EP – n/a
KW – climate
KW – climate change
KW – 1620 Climate dynamics
KW – 1616 Climate variability
KW – 1605 Abrupt/rapid climate change
PY – 2009
AB – This paper provides an update to an earlier work that showed specific changes in the aggregate time evolution of major Northern Hemispheric atmospheric and oceanic modes of variability serve as a harbinger of climate shifts. Specifically, when the major modes of Northern Hemisphere climate variability are synchronized, or resonate, and the coupling between those modes simultaneously increases, the climate system appears to be thrown into a new state, marked by a break in the global mean temperature trend and in the character of El Niño/Southern Oscillation variability. Here, a new and improved means to quantify the coupling between climate modes confirms that another synchronization of these modes, followed by an increase in coupling occurred in 2001/02. This suggests that a break in the global mean temperature trend from the consistent warming over the 1976/77–2001/02 period may have occurred.
ER –

NR – 54
TY – JOUR
AU – Shi, Yan
AU – Zhai, Panmao
AU – Jiang, Zhihong
PY – 2016
DA – 2016/04/01
TI – Multi-sliding time windows based changing trend of mean temperature and its association with the global-warming hiatus
JO – Journal of Meteorological Research
SP – 232
EP – 241
VL – 30
IS – 2
AB – Based on three global annual mean surface temperature time series and three Chinese annual mean surface air temperature time series, climate change trends on multiple timescales are analyzed by using the trend estimation method of multi-sliding time windows. The results are used to discuss the so-called global-warming hiatus during 1998–2012. It is demonstrated that different beginning and end times have an obvious effect on the results of the trend estimation, and the implications are particularly large when using a short window. The global-warming hiatus during 1998–2012 is the result of viewing temperature series on short timescales; and the events similar to it, or the events with even cold tendencies, have actually occurred many times in history. Therefore, the global-warming hiatus is likely to be a periodical feature of the long-term temperature change. It mainly reflects the decadal variability of temperature, and such a phenomenon in the short term does not alter the overall warming trend in the long term.
SN – 2198-0934
UR – https://doi.org/10.1007/s13351-016-5093-3
DO – 10.1007/s13351-016-5093-3
ID – Shi2016
ER –

NR – 55
TY – JOUR
T1 – Possible artifacts of data biases in the recent global surface warming hiatus
JF – Science
JO – Science
SP – 1469
LP – 1472
M3 – 10.1126/science.aaa5632
VL – 348
IS – 6242
AU – Karl, Thomas R.
AU – Arguez, Anthony
AU – Huang, Boyin
AU – Lawrimore, Jay H.
AU – McMahon, James R.
AU – Menne, Matthew J.
AU – Peterson, Thomas C.
AU – Vose, Russell S.
AU – Zhang, Huai-Min
Y1 – 2015/06/26
UR – http://science.sciencemag.org/content/348/6242/1469.abstract
N2 – Previous analyses of global temperature trends during the first decade of the 21st century seemed to indicate that warming had stalled. This allowed critics of the idea of global warming to claim that concern about climate change was misplaced. Karl et al. now show that temperatures did not plateau as thought and that the supposed warming “hiatus” is just an artifact of earlier analyses. Warming has continued at a pace similar to that of the last half of the 20th century, and the slowdown was just an illusion.Science, this issue p. 1469Much study has been devoted to the possible causes of an apparent decrease in the upward trend of global surface temperatures since 1998, a phenomenon that has been dubbed the global warming “hiatus.” Here, we present an updated global surface temperature analysis that reveals that global trends are higher than those reported by the Intergovernmental Panel on Climate Change, especially in recent decades, and that the central estimate for the rate of warming during the first 15 years of the 21st century is at least as great as the last half of the 20th century. These results do not support the notion of a “slowdown” in the increase of global surface temperature.
ER –

NR – 56
TY – JOUR
T1 – Relationship between the Arctic oscillation and surface air temperature in multi-decadal time-scale
AU – Tanaka, Hiroshi L.
AU – Tamura, Mina
JO – Polar Science
VL – 10
IS – 3
SP – 199
EP – 209
PY – 2016
DA – 2016/09/01/
T2 – ISAR-4/ICARPIII, Science Symposium of ASSW2015
SN – 1873-9652
DO – https://doi.org/10.1016/j.polar.2016.03.002
UR – http://www.sciencedirect.com/science/article/pii/S1873965216300093
KW – Arctic oscillation
KW – Arctic amplification
KW – Energy balance model
KW – Planetary albedo
KW – Multi-decadal variability
AB – In this study, a simple energy balance model (EBM) was integrated in time, considering a hypothetical long-term variability in ice-albedo feedback mimicking the observed multi-decadal temperature variability. A natural variability was superimposed on a linear warming trend due to the increasing radiative forcing of CO2. The result demonstrates that the superposition of the natural variability and the background linear trend can offset with each other to show the warming hiatus for some period. It is also stressed that the rapid warming during 1970–2000 can be explained by the superposition of the natural variability and the background linear trend at least within the simple model. The key process of the fluctuating planetary albedo in multi-decadal time scale is investigated using the JRA-55 reanalysis data. It is found that the planetary albedo increased for 1958–1970, decreased for 1970–2000, and increased for 2000–2012, as expected by the simple EBM experiments. The multi-decadal variability in the planetary albedo is compared with the time series of the AO mode and Barents Sea mode of surface air temperature. It is shown that the recent AO negative pattern showing warm Arctic and cold mid-latitudes is in good agreement with planetary albedo change indicating negative anomaly in high latitudes and positive anomaly in mid-latitudes. Moreover, the Barents Sea mode with the warm Barents Sea and cold mid-latitudes shows long-term variability similar to planetary albedo change. Although further studies are needed, the natural variabilities of both the AO mode and Barents Sea mode indicate some possible link to the planetary albedo as suggested by the simple EBM to cause the warming hiatus in recent years.
ER –

NR – 57
TY – JOUR
T1 – A Quantitative Definition of Global Warming Hiatus and 50-Year Prediction of Global-Mean Surface Temperature
AU – Wei, Meng
AU – Qiao, Fangli
AU – Deng, Jia
Y1 – 2015/05/15
PY – 2015
DA – 2015/08/01
N1 – doi: 10.1175/JAS-D-14-0296.1
DO – 10.1175/JAS-D-14-0296.1
T2 – Journal of the Atmospheric Sciences
JF – Journal of the Atmospheric Sciences
JO – J. Atmos. Sci.
SP – 3281
EP – 3289
VL – 72
IS – 8
PB – American Meteorological Society
N2 – AbstractRecent global warming hiatus has received much attention; however, a robust and quantitative definition for the hiatus is still lacking. Recent studies by Scafetta, Wu et al., and Tung and Zhou showed that multidecadal variability (MDV) is responsible for the multidecadal accelerated warming and hiatuses in historical global-mean surface temperature (GMST) records, though MDV itself has not received sufficient attention thus far. Here, the authors introduce four key episodes in GMST evolution, according to different phases of the MDV extracted by the ensemble empirical-mode decomposition method from the ensemble HadCRUT4 monthly GMST time series. The ?warming (cooling) hiatus? and ?typical warming (cooling)? periods are defined as the 95% confidence intervals for the locations of local MDV maxima (minima) and of their derivatives, respectively. Since 1850, the warming hiatuses, cooling hiatuses, and typical warming have already occurred three times and the typical cooling has occurred twice. At present, the MDV is in its third warming-hiatus period, which started in 2012 and would last until 2017, followed by a 30-yr cooling episode, while the trend will sustain the current steady growth in the next 50 years. Their superposition presents steplike rising since 1850. It is currently ascending a new height and will stay there until the next warming phase of the MDV carries it higher.
AB – AbstractRecent global warming hiatus has received much attention; however, a robust and quantitative definition for the hiatus is still lacking. Recent studies by Scafetta, Wu et al., and Tung and Zhou showed that multidecadal variability (MDV) is responsible for the multidecadal accelerated warming and hiatuses in historical global-mean surface temperature (GMST) records, though MDV itself has not received sufficient attention thus far. Here, the authors introduce four key episodes in GMST evolution, according to different phases of the MDV extracted by the ensemble empirical-mode decomposition method from the ensemble HadCRUT4 monthly GMST time series. The ?warming (cooling) hiatus? and ?typical warming (cooling)? periods are defined as the 95% confidence intervals for the locations of local MDV maxima (minima) and of their derivatives, respectively. Since 1850, the warming hiatuses, cooling hiatuses, and typical warming have already occurred three times and the typical cooling has occurred twice. At present, the MDV is in its third warming-hiatus period, which started in 2012 and would last until 2017, followed by a 30-yr cooling episode, while the trend will sustain the current steady growth in the next 50 years. Their superposition presents steplike rising since 1850. It is currently ascending a new height and will stay there until the next warming phase of the MDV carries it higher.
SN – 0022-4928
M3 – doi: 10.1175/JAS-D-14-0296.1
UR – https://doi.org/10.1175/JAS-D-14-0296.1
Y2 – 2018/02/02
ER –

NR – 58
TY – JOUR
AU – Cohen, Judah L.
AU – Furtado, Jason C.
AU – Barlow, Mathew
AU – Alexeev, Vladimir A.
AU – Cherry, Jessica E.
C8 – L04705
TI – Asymmetric seasonal temperature trends
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 39
IS – 4
SN – 1944-8007
UR – http://dx.doi.org/10.1029/2011GL050582
DO – 10.1029/2011GL050582
SP – n/a
EP – n/a
KW – climate change
KW – regional climate change
KW – temperature trends
KW – 1616 Climate variability
KW – 1620 Climate dynamics
KW – 1626 Global climate models
KW – 1627 Coupled models of the climate system
KW – 1637 Regional climate change
PY – 2012
AB – Current consensus on global climate change predicts warming trends driven by anthropogenic forcing, with maximum temperature changes projected in the Northern Hemisphere (NH) high latitudes during winter. Yet, global temperature trends show little warming over the most recent decade or so. For longer time periods appropriate to the assessment of trends, however, global temperatures have experienced significant warming trends for all seasons except winter, when cooling trends exist instead across large stretches of eastern North America and northern Eurasia. Hence, the most recent lapse in global warming is a seasonal phenomenon, prevalent only in boreal winter. Additionally, we show that the largest regional contributor to global temperature trends over the past two decades is land surface temperatures in the NH extratropics. Therefore, proposed mechanisms explaining the fluctuations in global annual temperatures should address this apparent seasonal asymmetry.
ER –

NR – 59
TY – JOUR
AU – Brown, Patrick T.
AU – Li, Wenhong
AU – Cordero, Eugene C.
AU – Mauget, Steven A.
TI – Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise
JA – Scientific Reports
PY – 2015/04/21/online
VL – 5
SP – 9957
EP –
PB – The Author(s)
SN –
UR – http://dx.doi.org/10.1038/srep09957
L3 – 10.1038/srep09957
M3 – Article
L3 – https://www.nature.com/articles/srep09957#supplementary-information
AB – The comparison of observed global mean surface air temperature (GMT) change to the mean change simulated by climate models has received much public and scientific attention. For a given global warming signal produced by a climate model ensemble, there exists an envelope of GMT values representing the range of possible unforced states of the climate system (the Envelope of Unforced Noise; EUN). Typically, the EUN is derived from climate models themselves, but climate models might not accurately simulate the correct characteristics of unforced GMT variability. Here, we simulate a new, empirical, EUN that is based on instrumental and reconstructed surface temperature records. We compare the forced GMT signal produced by climate models to observations while noting the range of GMT values provided by the empirical EUN. We find that the empirical EUN is wide enough so that the interdecadal variability in the rate of global warming over the 20th century does not necessarily require corresponding variability in the rate-of-increase of the forced signal. The empirical EUN also indicates that the reduced GMT warming over the past decade or so is still consistent with a middle emission scenario’s forced signal, but is likely inconsistent with the steepest emission scenario’s forced signal.
ER –

NR – 60
TY – JOUR
AU – Rajaratnam, Bala
AU – Romano, Joseph
AU – Tsiang, Michael
AU – Diffenbaugh, Noah S.
PY – 2015
DA – 2015/11/01
TI – Debunking the climate hiatus
JO – Climatic Change
SP – 129
EP – 140
VL – 133
IS – 2
AB – The reported “hiatus” in the warming of the global climate system during this century has been the subject of intense scientific and public debate, with implications ranging from scientific understanding of the global climate sensitivity to the rate in which greenhouse gas emissions would need to be curbed in order to meet the United Nations global warming target. A number of scientific hypotheses have been put forward to explain the hiatus, including both physical climate processes and data artifacts. However, despite the intense focus on the hiatus in both the scientific and public arenas, rigorous statistical assessment of the uniqueness of the recent temperature time-series within the context of the long-term record has been limited. We apply a rigorous, comprehensive statistical analysis of global temperature data that goes beyond simple linear models to account for temporal dependence and selection effects. We use this framework to test whether the recent period has demonstrated i) a hiatus in the trend in global temperatures, ii) a temperature trend that is statistically distinct from trends prior to the hiatus period, iii) a “stalling” of the global mean temperature, and iv) a change in the distribution of the year-to-year temperature increases. We find compelling evidence that recent claims of a “hiatus” in global warming lack sound scientific basis. Our analysis reveals that there is no hiatus in the increase in the global mean temperature, no statistically significant difference in trends, no stalling of the global mean temperature, and no change in year-to-year temperature increases.
SN – 1573-1480
UR – https://doi.org/10.1007/s10584-015-1495-y
DO – 10.1007/s10584-015-1495-y
ID – Rajaratnam2015
ER –

NR – 61
TY – JOUR
AU – Wang, Yuan
AU – Su, Hui
AU – Jiang, Jonathan H.
AU – Livesey, Nathaniel J.
AU – Santee, Michelle L.
AU – Froidevaux, Lucien
AU – Read, William G.
AU – Anderson, John
PY – 2017
DA – 2017/04/01
TI – The linkage between stratospheric water vapor and surface temperature in an observation-constrained coupled general circulation model
JO – Climate Dynamics
SP – 2671
EP – 2683
VL – 48
IS – 7
AB – We assess the interactions between stratospheric water vapor (SWV) and surface temperature during the past two decades using satellite observations and the Community Earth System Model (CESM). From 1992 to 2013, to first order, the observed SWV exhibited three distinct piece-wise trends: a steady increase from 1992 to 2000, an abrupt drop from 2000 to 2004, and a gradual recovery after 2004, while the global-mean surface temperature experienced a strong increase until 2000 and a warming hiatus after 2000. The atmosphere-only CESM shows that the seasonal variation of tropical-mean (30°S–30°N) SWV is anticorrelated with that of the tropical-mean sea surface temperature (SST), while the correlation between the tropical SWV and SST anomalies on the interannual time scale is rather weak. By nudging the modeled SWV to prescribed profiles in coupled atmosphere-slab ocean experiments, we investigate the impact of SWV variations on surface temperature change. We find that a uniform 1 ppmv (0.5 ppmv) SWV increase (decrease) leads to an equilibrium global mean surface warming (cooling) of 0.12 ± 0.05 °C (-0.07 ± 0.05 °C). Sensitivity experiments show that the equilibrium response of global mean surface temperature to SWV perturbations over the extratropics is larger than that over the tropics. The observed sudden drop of SWV from 2000 to 2004 produces a global mean surface cooling of about -0.048 ± 0.041 °C, which suggests that a persistent change in SWV would make an imprint on long-term variations of global-mean surface temperature. A constant linear increase in SWV based on the satellite-observed rate of SWV change yields a global mean surface warming of 0.03 ± 0.01 °C/decade over a 50-year period, which accounts for about 19 % of the observed surface temperature increase prior to the warming hiatus. In the same experiment, trend analyses during different periods reveal a multi-year adjustment of surface temperature before the response to SWV forcing becomes strong relative to the internal variability in the model.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-016-3231-3
DO – 10.1007/s00382-016-3231-3
ID – Wang2017
ER –

NR – 62
TY – JOUR
AU – Amaya, Dillon J.
AU – Xie, Shang-Ping
AU – Miller, Arthur J.
AU – McPhaden, Michael J.
TI – Seasonality of tropical Pacific decadal trends associated with the 21st century global warming hiatus
JO – Journal of Geophysical Research: Oceans
JA – J. Geophys. Res. Oceans
VL – 120
IS – 10
SN – 2169-9291
UR – http://dx.doi.org/10.1002/2015JC010906
DO – 10.1002/2015JC010906
SP – 6782
EP – 6798
KW – global warming hiatus
KW – Pacific decadal shifts
KW – tropical ocean variability
KW – seasonal variations
KW – Pacific Decadal Oscillation
KW – 1616 Climate variability
KW – 4513 Decadal ocean variability
KW – 4504 Air/sea interactions
KW – 4227 Diurnal, seasonal, and annual cycles
KW – 4231 Equatorial oceanography
PY – 2015
AB – Equatorial Pacific changes during the transition from a nonhiatus period (pre-1999) to the present global warming hiatus period (post-1999) are identified using a combination of reanalysis and observed data sets. Results show increased surface wind forcing has excited significant changes in wind-driven circulation. Over the last two decades, the core of the Equatorial Undercurrent intensified at a rate of 6.9 cm s-1 decade-1. Similarly, equatorial upwelling associated with the shallow meridional overturning circulation increased at a rate of 2.0 × 10-4 cm s-1 decade-1 in the central Pacific. Further, a seasonal dependence is identified in the sea surface temperature trends and in subsurface dynamics. Seasonal variations are evident in reversals of equatorial surface flow trends, changes in subsurface circulation, and seasonal deepening/shoaling of the thermocline. Anomalous westward surface flow drives cold-water zonal advection from November to February, leading to surface cooling from December through May. Conversely, eastward surface current anomalies in June–July drive warm-water zonal advection producing surface warming from July to November. An improved dynamical understanding of how the tropical Pacific Ocean responds during transitions into hiatus events, including its seasonal structure, may help to improve future predictability of decadal climate variations.
ER –

NR – 63
TY – JOUR
TI – The “Artefacts” of Data Biases in Surface Temperatures are Hiding the Hiatus
AU – Parker, A.
PY – 2015
JO – American Journal of Geophysics, Geochemistry and Geosystems
VL – 1
IS – 3
UR – http://files.aiscience.org/journal/article/pdf/70170008.pdf
SP – 66
EP – 70
AB – As almost any trend can be built by continuous tampering of past information rather than simply keeping the computational procedure unaltered and updating the data sets with freshly measured data, the latest paper published by NOAA in Science that negates the “hiatus” in global warming since 1998 also admitted by the IPCC is not a surprise. However, this prompts serious questions about the political bias of high impact factor journals. My contribution shows the information from conflicting data sets of measured lower troposphere temperatures and reconstructed surface air temperatures continuously corrected.
ER –

NR – 64
TY – JOUR
AU – Lean, Judith L.
AU – Rind, David H.
C8 – L15708
TI – How will Earth’s surface temperature change in future decades?
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 36
IS – 15
SN – 1944-8007
UR – http://dx.doi.org/10.1029/2009GL038932
DO – 10.1029/2009GL038932
SP – n/a
EP – n/a
KW – climate forecast
KW – 1616 Climate variability
KW – 1637 Regional climate change
KW – 1650 Solar variability
PY – 2009
AB – Reliable forecasts of climate change in the immediate future are difficult, especially on regional scales, where natural climate variations may amplify or mitigate anthropogenic warming in ways that numerical models capture poorly. By decomposing recent observed surface temperatures into components associated with ENSO, volcanic and solar activity, and anthropogenic influences, we anticipate global and regional changes in the next two decades. From 2009 to 2014, projected rises in anthropogenic influences and solar irradiance will increase global surface temperature 0.15 ± 0.03°C, at a rate 50% greater than predicted by IPCC. But as a result of declining solar activity in the subsequent five years, average temperature in 2019 is only 0.03 ± 0.01°C warmer than in 2014. This lack of overall warming is analogous to the period from 2002 to 2008 when decreasing solar irradiance also countered much of the anthropogenic warming. We further illustrate how a major volcanic eruption and a super ENSO would modify our global and regional temperature projections.
ER –

NR – 65
TY – JOUR
AU – Saenko, Oleg A.
AU – Fyfe, John C.
AU – Swart, Neil C.
AU – Lee, Warren G.
AU – England, Matthew H.
PY – 2016
DA – 2016/10/01
TI – Influence of tropical wind on global temperature from months to decades
JO – Climate Dynamics
SP – 2193
EP – 2203
VL – 47
IS – 7
AB – Using an Earth System Model and observations we analyze the sequence of events connecting episodes of trade wind strengthening (or weakening) to global mean surface temperature (GMST) cooling (or warming), with tropical ocean wave dynamics partially setting the time scale. In this sequence tropical west Pacific wind stress signals lead equatorial east Pacific thermocline depth signals which lead tropical east Pacific sea surface temperature (SST) signals which lead GMST signals. Using the anthropogenic, natural and tropical wind signals extracted from our simulations in a multivariate linear regression with observed GMST makes clear the balance that exists between anthropogenic warming and tropical wind-induced cooling during the recent warming slowdown, and between volcanic cooling and tropical wind-induced warming during the El Chichón and Pinatubo eruptions. Finally, we find an anticorrelation between global-mean temperatures in the near-surface (upper ~100 m) and subsurface (~100–300 m) ocean layers, linked to wind-driven interannual to decadal variations in the strength of the subtropical cell overturning in the upper Pacific Ocean.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-015-2958-6
DO – 10.1007/s00382-015-2958-6
ID – Saenko2016
ER –

NR – 66
TY – JOUR
T1 – A Link between the Hiatus in Global Warming and North American Drought
AU – Delworth, Thomas L.
AU – Zeng, Fanrong
AU – Rosati, Anthony
AU – Vecchi, Gabriel A.
AU – Wittenberg, Andrew T.
Y1 – 2015/03/10
PY – 2015
DA – 2015/05/01
N1 – doi: 10.1175/JCLI-D-14-00616.1
DO – 10.1175/JCLI-D-14-00616.1
T2 – Journal of Climate
JF – Journal of Climate
JO – J. Climate
SP – 3834
EP – 3845
VL – 28
IS – 9
PB – American Meteorological Society
N2 – AbstractPortions of western North America have experienced prolonged drought over the last decade. This drought has occurred at the same time as the global warming hiatus?a decadal period with little increase in global mean surface temperature. Climate models and observational analyses are used to clarify the dual role of recent tropical Pacific changes in driving both the global warming hiatus and North American drought. When observed tropical Pacific wind stress anomalies are inserted into coupled models, the simulations produce persistent negative sea surface temperature anomalies in the eastern tropical Pacific, a hiatus in global warming, and drought over North America driven by SST-induced atmospheric circulation anomalies. In the simulations herein the tropical wind anomalies account for 92% of the simulated North American drought during the recent decade, with 8% from anthropogenic radiative forcing changes. This suggests that anthropogenic radiative forcing is not the dominant driver of the current drought, unless the wind changes themselves are driven by anthropogenic radiative forcing. The anomalous tropical winds could also originate from coupled interactions in the tropical Pacific or from forcing outside the tropical Pacific. The model experiments suggest that if the tropical winds were to return to climatological conditions, then the recent tendency toward North American drought would diminish. Alternatively, if the anomalous tropical winds were to persist, then the impact on North American drought would continue; however, the impact of the enhanced Pacific easterlies on global temperature diminishes after a decade or two due to a surface reemergence of warmer water that was initially subducted into the ocean interior.
AB – AbstractPortions of western North America have experienced prolonged drought over the last decade. This drought has occurred at the same time as the global warming hiatus?a decadal period with little increase in global mean surface temperature. Climate models and observational analyses are used to clarify the dual role of recent tropical Pacific changes in driving both the global warming hiatus and North American drought. When observed tropical Pacific wind stress anomalies are inserted into coupled models, the simulations produce persistent negative sea surface temperature anomalies in the eastern tropical Pacific, a hiatus in global warming, and drought over North America driven by SST-induced atmospheric circulation anomalies. In the simulations herein the tropical wind anomalies account for 92% of the simulated North American drought during the recent decade, with 8% from anthropogenic radiative forcing changes. This suggests that anthropogenic radiative forcing is not the dominant driver of the current drought, unless the wind changes themselves are driven by anthropogenic radiative forcing. The anomalous tropical winds could also originate from coupled interactions in the tropical Pacific or from forcing outside the tropical Pacific. The model experiments suggest that if the tropical winds were to return to climatological conditions, then the recent tendency toward North American drought would diminish. Alternatively, if the anomalous tropical winds were to persist, then the impact on North American drought would continue; however, the impact of the enhanced Pacific easterlies on global temperature diminishes after a decade or two due to a surface reemergence of warmer water that was initially subducted into the ocean interior.
SN – 0894-8755
M3 – doi: 10.1175/JCLI-D-14-00616.1
UR – https://doi.org/10.1175/JCLI-D-14-00616.1
Y2 – 2018/02/09
ER –

NR – 67
TY – JOUR
T1 – A perspective on sustained marine observations for climate modelling and prediction
JF – Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
JO – Philos Transact A Math Phys Eng Sci
M3 – 10.1098/rsta.2013.0340
VL – 372
IS – 2025
AU – Dunstone, Nick J.
Y1 – 2014/09/28
UR – http://rsta.royalsocietypublishing.org/content/372/2025/20130340.abstract
N2 – Here, I examine some of the many varied ways in which sustained global ocean observations are used in numerical modelling activities. In particular, I focus on the use of ocean observations to initialize predictions in ocean and climate models. Examples are also shown of how models can be used to assess the impact of both current ocean observations and to simulate that of potential new ocean observing platforms. The ocean has never been better observed than it is today and similarly ocean models have never been as capable at representing the real ocean as they are now. However, there remain important unanswered questions that can likely only be addressed via future improvements in ocean observations. In particular, ocean observing systems need to respond to the needs of the burgeoning field of near-term climate predictions. Although new ocean observing platforms promise exciting new discoveries, there is a delicate balance to be made between their funding and that of the current ocean observing system. Here, I identify the need to secure long-term funding for ocean observing platforms as they mature, from a mainly research exercise to an operational system for sustained observation over climate change time scales. At the same time, considerable progress continues to be made via ship-based observing campaigns and I highlight some that are dedicated to addressing uncertainties in key ocean model parametrizations. The use of ocean observations to understand the prominent long time scale changes observed in the North Atlantic is another focus of this paper. The exciting first decade of monitoring of the Atlantic meridional overturning circulation by the RAPID-MOCHA array is highlighted. The use of ocean and climate models as tools to further probe the drivers of variability seen in such time series is another exciting development. I also discuss the need for a concerted combined effort from climate models and ocean observations in order to understand the current slow-down in surface global warming.
ER –

NR – 68
TY – JOUR
AU – Power, Scott
AU – Delage, François
AU – Wang, Guomin
AU – Smith, Ian
AU – Kociuba, Greg
PY – 2017
DA – 2017/07/01
TI – Apparent limitations in the ability of CMIP5 climate models to simulate recent multi-decadal change in surface temperature: implications for global temperature projections
JO – Climate Dynamics
SP – 53
EP – 69
VL – 49
IS – 1
AB – Observed surface temperature trends over the period 1998–2012/2014 have attracted a great deal of interest because of an apparent slowdown in the rate of global warming, and contrasts between climate model simulations and observations of such trends. Many studies have addressed the statistical significance of these relatively short-trends, whether they indicate a possible bias in the model values and the implications for global warming generally. Here we re-examine these issues, but as they relate to changes over much longer-term changes. We find that on multi-decadal time scales there is little evidence for any change in the observed global warming rate, but some evidence for a recent temporary slowdown in the warming rate in the Pacific. This multi-decadal slowdown can be partly explained by a cool phase of the Interdecadal Pacific Oscillation and a short-term excess of La Niña events. We also analyse historical and projected changes in 38 CMIP climate models. All of the model simulations examined simulate multi-decadal warming in the Pacific over the past half-century that exceeds observed values. This difference cannot be fully explained by observed internal multi-decadal climate variability, even if allowance is made for an apparent tendency for models to underestimate internal multi-decadal variability in the Pacific. Models which simulate the greatest global warming over the past half-century also project warming that is among the highest of all models by the end of the twenty-first century, under both low and high greenhouse gas emission scenarios. Given that the same models are poorest in representing observed multi-decadal temperature change, confidence in the highest projections is reduced.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-016-3326-x
DO – 10.1007/s00382-016-3326-x
ID – Power2017
ER –

NR – 69
TY – JOUR
AU – Liao, Enhui
AU – Lu, Wenfang
AU – Yan, Xiao-Hai
AU – Jiang, Yuwu
AU – Kidwell, Autumn
TI – The coastal ocean response to the global warming acceleration and hiatus
JA – Scientific Reports
PY – 2015/11/16/online
VL – 5
SP – 16630
EP –
PB – The Author(s)
SN –
UR – http://dx.doi.org/10.1038/srep16630
L3 – 10.1038/srep16630
M3 – Article
L3 – https://www.nature.com/articles/srep16630#supplementary-information
AB – Coastlines are fundamental to humans for habitation, commerce, and natural resources. Many coastal ecosystem disasters, caused by extreme sea surface temperature (SST), were reported when the global climate shifted from global warming to global surface warming hiatus after 1998. The task of understanding the coastal SST variations within the global context is an urgent matter. Our study on the global coastal SST from 1982 to 2013 revealed a significant cooling trend in the low and mid latitudes (31.4% of the global coastlines) after 1998, while 17.9% of the global coastlines changed from a cooling trend to a warming trend concurrently. The trend reversals in the Northern Pacific and Atlantic coincided with the phase shift of Pacific Decadal Oscillation and North Atlantic Oscillation, respectively. These coastal SST changes are larger than the changes of the global mean and open ocean, resulting in a fast increase of extremely hot/cold days, and thus extremely hot/cold events. Meanwhile, a continuous increase of SST was detected for a considerable portion of coastlines (46.7%) with a strengthened warming along the coastlines in the high northern latitudes. This suggests the warming still continued and strengthened in some regions after 1998, but with a weaker pattern in the low and mid latitudes.
ER –

NR – 70
TY – JOUR
AU – Duan, Anmin
AU – Xiao, Zhixiang
TI – Does the climate warming hiatus exist over the Tibetan Plateau?
JF – Scientific Reports
PY – 2015/09/02/online
VL – 5
SP – 13711
EP –
PB – The Author(s)
SN –
UR – http://dx.doi.org/10.1038/srep13711
L3 – 10.1038/srep13711
M3 – Article
L3 – https://www.nature.com/articles/srep13711#supplementary-information
AB – The surface air temperature change over the Tibetan Plateau is determined based on historical observations from 1980 to 2013. In contrast to the cooling trend in the rest of China, and the global warming hiatus post-1990s, an accelerated warming trend has appeared over the Tibetan Plateau during 1998–2013 (0.25?°C decade-1), compared with that during 1980–1997 (0.21?°C decade-1). Further results indicate that, to some degree, such an accelerated warming trend might be attributable to cloud–radiation feedback. The increased nocturnal cloud over the northern Tibetan Plateau would warm the nighttime temperature via enhanced atmospheric back-radiation, while the decreased daytime cloud over the southern Tibetan Plateau would induce the daytime sunshine duration to increase, resulting in surface air temperature warming. Meanwhile, the in situ surface wind speed has recovered gradually since 1998, and thus the energy concentration cannot explain the accelerated warming trend over the Tibetan Plateau after the 1990s. It is suggested that cloud–radiation feedback may play an important role in modulating the recent accelerated warming trend over the Tibetan Plateau.
ER –

NR – 71
TY – JOUR
AU – Ducic, Vladan D.
AU – Milovanovic, Boško M.
AU – Stanojevic, Gorica B.
AU – Milenkovic, Milan Ð.
AU – Curcic, Nina B.
TI – Tropical temperature altitude amplification in the hiatus period (1998-2012)
JF – Thermal Science
PY – 2015
VL – 19
IS – 2
SP – 371
EP – 379
UR – http://dx.doi.org/10.2298/TSCI150410103D
DO – 10.2298/TSCI150410103D
AB – In the period 1998-2012 there was a stagnation in temperature rise, despite the GHGs radiation forcing is increased (hiatus period). According to Global Circulation Models simulations, expected response on the rise of GHGs forcing is tropical temperature altitude amplification – temperature increases faster in higher troposphere than in lower troposphere. In this paper, two satellite data sets, UAH MSU and RSS, were used to test altitude temperature amplification in tropic (20°N-20°S) in the hiatus period. We compared data from satellite data sets from lower troposphere (TLT) and middle troposphere (TMT) in general and particularly for land and ocean (for UAH MSU). The results from both satellite measurements showed the presence of hiatus, i.e. slowdown of the temperature rise in the period 1998-2012 compared to period 1979-2012 (UAH MSU) and temperature fall for RSS data. Smaller increase, i.e. temperature fall over ocean showed that hiatus is an ocean phenomenon above all. Data for UAH MSU showed that temperature altitude amplification in tropic was not present either for period 1979-2012, or 1998-2012. RSS data set also do not show temperature altitude amplification either for longer (1979-2012), or for shorter period (1998-2012). RSS data for successive 15-year periods from 1979-1993 till 1998-2012 does not show tropical temperature altitude amplification and in one case negative trend is registered in TLT and in two cases in TMT. In general, our results do not show presence of temperature altitude amplification in tropic in the hiatus period.
ER –

NR – 72
TY – JOUR
T1 – Does the Global Warming Pause in the Last Decade: 1999–2008?
AU – Wang, Shaowu
AU – Wen, Xinyu
AU – Luo, Yong
AU – Tang, Guoli
AU – Zhao, Zongci
AU – Huang, Jianbin
JO – Advances in Climate Change Research
VL – 1
IS – 1
SP – 49
EP – 54
PY – 2010
DA – 2010/08/01/
SN – 1674-9278
DO – https://doi.org/10.3724/SP.J.1248.2010.00049
UR – http://www.sciencedirect.com/science/article/pii/S167492781050008X
KW – 1999–2008
KW – global warming
KW – pause
AB – Issues related to the pause of global warming in the last decade are reviewed. It is indicated that: (1) The decade of 1999–2008 is still the warmest of the last 30 years, though the global temperature increment is near zero; (2) Natural factors such as volcanism, solar radiation, ENSO, and thermohaline circulation can have impact on the inter-annual and inter-decadal variability of global mean temperatures. However, it will not mask the global warming trend for a long time; (3) Temperatures of China continue to increase in 1999–2008 with an increment of 0.4–0.5°C per 10 years.
ER –

NR – 73
TY – JOUR
AU – Kumar, Sanjiv
AU – Kinter, James L.
AU – Pan, Zaitao
AU – Sheffield, Justin
C8 – 2015JD024382
TI – Twentieth century temperature trends in CMIP3, CMIP5, and CESM-LE climate simulations: Spatial-temporal uncertainties, differences, and their potential sources
JO – Journal of Geophysical Research: Atmospheres
JA – J. Geophys. Res. Atmos.
VL – 121
IS – 16
SN – 2169-8996
UR – http://dx.doi.org/10.1002/2015JD024382
DO – 10.1002/2015JD024382
SP – 9561
EP – 9575
KW – CMIP3
KW – CMIP5
KW – historical climate
KW – large ensemble
KW – temperature trend
KW – 1620 Climate dynamics
KW – 1622 Earth system modeling
KW – 1626 Global climate models
KW – 1637 Regional climate change
PY – 2016
AB – The twentieth century climate simulations from the Coupled Model Intercomparison Project Phase 3 (CMIP3) and Phase 5 (CMIP5) are compared to assess the models’ ability to capture observed near-surface air temperature trends at global, continental, and regional scales. We computed trends by using a nonparametric method and considering long-term persistence in the time series. The role of internal variability is examined by using large ensemble climate simulations from the National Center for Atmospheric Research model Community Earth System Model (CESM). We computed temperature trends for three periods: the twentieth century, the second half of the twentieth century, and (3) the recent hiatus period to contrast the roles of external forcing and internal variability at various spatial and temporal scales. Both CMIP ensembles show statistically significant warming at global and continental scales during the twentieth century. We found a small but statistically significant difference between CMIP3 (0.57?±?0.07?°C/century) and CMIP5 (0.47?±?0.06?°C/century) twentieth century temperature trends, with the CMIP3 estimate being closer to the observations. The spatial structure of long-term temperature trends, and top-of-the atmosphere net radiation trends, suggests that differences in model parameterizations and feedback processes that lead to a smaller net radiative forcing are likely contributing to the differences between CMIP3 and CMIP5. The estimate of internal variability based on the CESM large ensemble spans 24% of the uncertainty in CMIP5 for the twentieth century temperature trends, and 76% for the recent hiatus period, both at global scales, and 43% and almost 100% during the corresponding time periods at regional scales.
ER –

NR – 74
TY – JOUR
AU – Huang, Jianping
AU – Xie, Yongkun
AU – Guan, Xiaodan
AU – Li, Dongdong
AU – Ji, Fei
PY – 2017
DA – 2017/01/01
TI – The dynamics of the warming hiatus over the Northern Hemisphere
JO – Climate Dynamics
SP – 429
EP – 446
VL – 48
IS – 1
AB – A warming hiatus is a period of relatively little change in global mean surface air temperatures (SAT). Many studies have attributed the current warming hiatus to internal climate variability (ICV). But there is less work on discussion of the dynamics about how these ICV modes influence cooling over land in the Northern Hemisphere (NH). Here we demonstrate the warming hiatus was more significant over the continental NH. We explored the dynamics of the warming hiatus from a global perspective and investigated the mechanisms of the reversing from accelerated warming to hiatus, and how ICV modes influence SAT change throughout the NH land. It was found that these ICV modes and Arctic amplification can excite a decadal modulated oscillation (DMO), which enhances or suppresses the long-term trend on decadal to multi-decadal timescales. When the DMO is in an upward (warming) phase, it contributes to an accelerated warming trend, as in last 20 years of twentieth-century. It appears that there is a downward swing in the DMO occurring at present, which has balanced or reduced the radiative forced warming and resulted in the recent global warming hiatus. The DMO modulates the SAT, in particular, the SAT of boreal cold months, through changes in the asymmetric meridional and zonal thermal forcing (MTF and ZTF). The MTF represents the meridional temperature gradients between the mid- and high-latitudes, and the ZTF represents the asymmetry in temperatures between the extratropical large-scale warm and cold zones in the zonal direction. Via the different performance of combined MTF and ZTF, we found that the DMO’s modulation effect on SAT was strongest when both weaker (stronger) MTF and stronger (weaker) ZTF occurred simultaneously. And the current hiatus is a result of a downward DMO combined with a weaker MTF and stronger ZTF, which stimulate both a weaker polar vortex and westerly winds, along with the amplified planetary waves, thereby facilitating southward invasion of cold Arctic-air and promoting the blocking formation. The results conclude that the DMO can not only be used to interpret the current warming hiatus, it also suggests that global warming will accelerate again when it swings upward.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-016-3085-8
DO – 10.1007/s00382-016-3085-8
ID – Huang2017
ER –

NR – 75
TY – JOUR
AU – Ma, Ying
AU – Mao, Rui
AU – Feng, Sheng-Hui
AU – Gong, Dao-Yi
AU – Kim, Seong-Joong
TI – Does the recent warming hiatus exist over Northern Asia for winter wind chill temperature?
JO – International Journal of Climatology
JA – Int. J. Climatol.
VL – 37
IS – 7
PB – John Wiley & Sons, Ltd
SN – 1097-0088
UR – http://dx.doi.org/10.1002/joc.4905
DO – 10.1002/joc.4905
SP – 3138
EP – 3144
KW – wind chill temperature
KW – Northern Asia
KW – warming hiatus
PY – 2017
AB – Wind chill temperature (WCT) describes the joint effect of wind velocity and air temperature on exposed body skin and could support policymakers in designing plans to reduce the risks of notably cold and windy weather. This study examined winter WCT over Northern Asia during 1973–2013 by analysing in situ station data. The winter WCT warming rate over the Tibetan Plateau (TP) slowed during 1999–2013 (-0.04?°C?decade-1) compared with that of during 1973–1998 (0.67?°C?decade-1). The winter WCT warming hiatus has also been observed in the remainder of Northern Asia with trends of 1.11?°C?decade-1 during 1973–1998 but -1.02?°C?decade-1 during 1999–2013, except for the Far East (FE) of Russia, where the winter WCT has continued to heat up during both the earlier period of 1973–1998 (0.54?°C?decade-1) and the recent period of 1999–2013 (0.75?°C?decade-1). The results indicate that the influence of temperature on winter WCT is greater than that of wind speed over Northern Asia. Atmospheric circulation changes associated with air temperature and wind speed were analysed to identify the causes for the warming hiatus of winter WCT over Northern Asia. The distributions of sea-level pressure and 500-hPa height anomalies during 1999–2013 transported cold air from the high latitudes to middle latitudes, resulting in low air temperature over Northern Asia except for the FE of Russia. Over the TP, the increase in wind speed offset the increase in air temperature during 1999–2013. For the FE, the southerly wind from the Western Pacific drove the temperature up during the 1999–2013 period through warm advection.
ER –

NR – 76
TY – JOUR
AU – Douville, H.
AU – Voldoire, A.
AU – Geoffroy, O.
C8 – 2014GL062775
TI – The recent global warming hiatus: What is the role of Pacific variability?
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 42
IS – 3
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL062775
DO – 10.1002/2014GL062775
SP – 880
EP – 888
KW – global warming
KW – hiatus
KW – ENSO
KW – 1616 Climate variability
KW – 1635 Oceans
KW – 1626 Global climate models
KW – 4522 ENSO
PY – 2015
AB – The observed global mean surface air temperature (GMST) has not risen over the last 15?years, spurring outbreaks of skepticism regarding the nature of global warming and challenging the upper range transient response of the current-generation global climate models. Recent numerical studies have, however, tempered the relevance of the observed pause in global warming by highlighting the key role of tropical Pacific internal variability. Here we first show that many climate models overestimate the influence of the El Niño–Southern Oscillation on GMST, thereby shedding doubt on their ability to capture the tropical Pacific contribution to the hiatus. Moreover, we highlight that model results can be quite sensitive to the experimental design. We argue that overriding the surface wind stress is more suitable than nudging the sea surface temperature for controlling the tropical Pacific ocean heat uptake and, thereby, the multidecadal variability of GMST. Using the former technique, our model captures several aspects of the recent climate evolution, including the weaker slowdown of global warming over land and the transition toward a negative phase of the Pacific Decadal Oscillation. Yet the observed global warming is still overestimated not only over the recent 1998–2012 hiatus period but also over former decades, thereby suggesting that the model might be too sensitive to the prescribed radiative forcings.
ER –

NR – 77
TY – JOUR
AU – Schurer, Andrew P.
AU – Hegerl, Gabriele C.
AU – Obrochta, Stephen P.
C8 – 2015GL064458
TI – Determining the likelihood of pauses and surges in global warming
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 42
IS – 14
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2015GL064458
DO – 10.1002/2015GL064458
SP – 5974
EP – 5982
KW – natural climate variability
KW – 1616 Climate variability
KW – 1626 Global climate models
KW – 3305 Climate change and variability
KW – 4215 Climate and interannual variability
KW – 8408 Volcano/climate interactions
PY – 2015
AB – The recent warming “hiatus” is subject to intense interest, with proposed causes including natural forcing and internal variability. Here we derive samples of all natural and internal variability from observations and a recent proxy reconstruction to investigate the likelihood that these two sources of variability could produce a hiatus or rapid warming in surface temperature. The likelihood is found to be consistent with that calculated previously for models and exhibits a similar spatial pattern, with an Interdecadal Pacific Oscillation-like structure, although with more signal in the Atlantic than in model patterns. The number and length of events increases if natural forcing is also considered, particularly in the models. From the reconstruction it can be seen that large eruptions, such as Mount Tambora in 1815, or clusters of eruptions, may result in a hiatus of over 20?years, a finding supported by model results.
ER –

NR – 78
TY – JOUR
AU – Ou, Nian-Sen
AU – Lin, Yi-Hua
AU – Bi, Xun-Qiang
PY – 2015
TI – Simulated Heat Sink in the Southern Ocean and Its Contribution to the Recent Hiatus Decade
JO – Atmospheric and Oceanic Science Letters
VL – 8
IS – 3
SP – 174
EP – 178
UR – http://dx.doi.org/10.3878/AOSL20150008
DO – 10.3878/AOSL20150008
AB – A set of numerical experiments is designed and carried out to understand a heat sink in the Southern Ocean in the recent hiatus decade. By using an oceanic general circulation model, the authors focus on the contributions from two types of forcing: wind stress and thermohaline forcing. The simulated results show that the heat sink in the upper Southern Ocean comes mainly from thermohaline forcing; while in the deeper layers, wind stress forcing also plays an important role. These different contributions may be due to different physical processes for the heat budget. The combination of these two types of forcing shows a significant heat sink in the Southern Ocean in the recent hiatus decade, and this is consistent with the observations and conclusions of a similar recently published study.
ER –

NR – 79
TY – JOUR
AU – Kosaka, Yu
AU – Xie, Shang-Ping
TI – The tropical Pacific as a key pacemaker of the variable rates of global warming
JO – Nature Geoscience
PY – 2016/07/18/online
VL – 9
SP – 669
PB – Nature Publishing Group
UR – http://dx.doi.org/10.1038/ngeo2770
DO – 10.1038/ngeo2770
L3 – https://www.nature.com/articles/ngeo2770#supplementary-information
AB – Global mean surface temperature change over the past 120 years resembles a rising staircase1,2: the overall warming trend was interrupted by the mid-twentieth-century big hiatus and the warming slowdown2,3,4,5,6,7,8 since about 1998. The Interdecadal Pacific Oscillation9,10 has been implicated in modulations of global mean surface temperatures6,11, but which part of the mode drives the variability in warming rates is unclear. Here we present a successful simulation of the global warming staircase since 1900 with a global ocean–atmosphere coupled model where tropical Pacific sea surface temperatures are forced to follow the observed evolution. Without prescribed tropical Pacific variability, the same model, on average, produces a continual warming trend that accelerates after the 1960s. We identify four events where the tropical Pacific decadal cooling markedly slowed down the warming trend. Matching the observed spatial and seasonal fingerprints we identify the tropical Pacific as a key pacemaker of the warming staircase, with radiative forcing driving the overall warming trend. Specifically, tropical Pacific variability amplifies the first warming epoch of the 1910s–1940s and determines the timing when the big hiatus starts and ends. Our method of removing internal variability from the observed record can be used for real-time monitoring of anthropogenic warming.
ER –

NR – 80
TY – JOUR
AU – Yan, Xiao-Hai
AU – Boyer, Tim
AU – Trenberth, Kevin
AU – Karl, Thomas R.
AU – Xie, Shang-Ping
AU – Nieves, Veronica
AU – Tung, Ka-Kit
AU – Roemmich, Dean
C8 – 2016EF000417
TI – The global warming hiatus: Slowdown or redistribution?
JO – Earth’s Future
JA – Earth’s Future
VL – 4
IS – 11
PB – Wiley Periodicals, Inc.
SN – 2328-4277
UR – http://dx.doi.org/10.1002/2016EF000417
DO – 10.1002/2016EF000417
SP – 472
EP – 482
KW – Global warming hiatus
KW – Heat energy
KW – Ocean monitoring
KW – 4215 Climate and interannual variability
KW – 4262 Ocean observing systems
KW – 4513 Decadal ocean variability
KW – 4504 Air/sea interactions
PY – 2016
AB – Global mean surface temperatures (GMST) exhibited a smaller rate of warming during 1998–2013, compared to the warming in the latter half of the 20th Century. Although, not a “true” hiatus in the strict definition of the word, this has been termed the “global warming hiatus” by IPCC (2013). There have been other periods that have also been defined as the “hiatus” depending on the analysis. There are a number of uncertainties and knowledge gaps regarding the “hiatus.” This report reviews these issues and also posits insights from a collective set of diverse information that helps us understand what we do and do not know. One salient insight is that the GMST phenomenon is a surface characteristic that does not represent a slowdown in warming of the climate system but rather is an energy redistribution within the oceans. Improved understanding of the ocean distribution and redistribution of heat will help better monitor Earth’s energy budget and its consequences. A review of recent scientific publications on the “hiatus” shows the difficulty and complexities in pinpointing the oceanic sink of the “missing heat” from the atmosphere and the upper layer of the oceans, which defines the “hiatus.” Advances in “hiatus” research and outlooks (recommendations) are given in this report.
ER –

NR – 81
TY – JOUR
T1 – Spatiotemporal Temperature Variability over the Tibetan Plateau: Altitudinal Dependence Associated with the Global Warming Hiatus
AU – Cai, Danlu
AU – You, Qinglong
AU – Fraedrich, Klaus
AU – Guan, Yanning
Y1 – 2016/10/24
PY – 2016
DA – 2017/02/01
N1 – doi: 10.1175/JCLI-D-16-0343.1
DO – 10.1175/JCLI-D-16-0343.1
T2 – Journal of Climate
JF – Journal of Climate
JO – J. Climate
SP – 969
EP – 984
VL – 30
IS – 3
PB – American Meteorological Society
N2 – AbstractThe recent slowdown in global warming has initiated a reanalysis of temperature data in some mountainous regions for understanding the consequences and impact that a hiatus has on the climate system. Spatiotemporal temperature variability is analyzed over the Tibetan Plateau because of its sensitivity to climate change with a station network updated to 2014, and its linkages to remote sensing?based variability of MODIS daytime and nighttime temperature are investigated. Results indicate the following: 1) Almost all stations have experienced a notable warming in the time interval 1961?2014, with most obvious warming in winter, which depends on the selected time intervals. 2) There is no clear shift from a predominant warming to a near stagnation during the most recent period (2001?present). 3) Uniform altitudinal dependence of temperature change trends could not be confirmed for all regions, time intervals, and seasons, but sometimes an altitude threshold around 3 km is apparent. 4) Most of the meteorological stations are associated with MODIS temperature warming pixels, and thus regional cooling is missing when considering only the locations of meteorological stations. In summarizing, previous studies based on station observations do not provide a complete picture for the temperature change over the Tibetan Plateau. Remote sensing?based analyses have the potential to find early signals of regional climate changes and assess the impact of global climate changes in complex regional, seasonal, and altitudinal environments.
AB – AbstractThe recent slowdown in global warming has initiated a reanalysis of temperature data in some mountainous regions for understanding the consequences and impact that a hiatus has on the climate system. Spatiotemporal temperature variability is analyzed over the Tibetan Plateau because of its sensitivity to climate change with a station network updated to 2014, and its linkages to remote sensing?based variability of MODIS daytime and nighttime temperature are investigated. Results indicate the following: 1) Almost all stations have experienced a notable warming in the time interval 1961?2014, with most obvious warming in winter, which depends on the selected time intervals. 2) There is no clear shift from a predominant warming to a near stagnation during the most recent period (2001?present). 3) Uniform altitudinal dependence of temperature change trends could not be confirmed for all regions, time intervals, and seasons, but sometimes an altitude threshold around 3 km is apparent. 4) Most of the meteorological stations are associated with MODIS temperature warming pixels, and thus regional cooling is missing when considering only the locations of meteorological stations. In summarizing, previous studies based on station observations do not provide a complete picture for the temperature change over the Tibetan Plateau. Remote sensing?based analyses have the potential to find early signals of regional climate changes and assess the impact of global climate changes in complex regional, seasonal, and altitudinal environments.
SN – 0894-8755
M3 – doi: 10.1175/JCLI-D-16-0343.1
UR – https://doi.org/10.1175/JCLI-D-16-0343.1
Y2 – 2018/02/19
ER –

NR – 82
TY – JOUR
AU – Rackow, T.
AU – Goessling, H. F.
AU – Jung, T.
AU – Sidorenko, D.
AU – Semmler, T.
AU – Barbi, D.
AU – Handorf, D.
PY – 2016
DA – 2016/06/04
TI – Towards multi-resolution global climate modeling with ECHAM6-FESOM. Part II: climate variability
JO – Climate Dynamics
AB – This study forms part II of two papers describing ECHAM6-FESOM, a newly established global climate model with a unique multi-resolution sea ice-ocean component. While part I deals with the model description and the mean climate state, here we examine the internal climate variability of the model under constant present-day (1990) conditions. We (1) assess the internal variations in the model in terms of objective variability performance indices, (2) analyze variations in global mean surface temperature and put them in context to variations in the observed record, with particular emphasis on the recent warming slowdown, (3) analyze and validate the most common atmospheric and oceanic variability patterns, (4) diagnose the potential predictability of various climate indices, and (5) put the multi-resolution approach to the test by comparing two setups that differ only in oceanic resolution in the equatorial belt, where one ocean mesh keeps the coarse ~1° resolution applied in the adjacent open-ocean regions and the other mesh is gradually refined to ~0.25°. Objective variability performance indices show that, in the considered setups, ECHAM6-FESOM performs overall favourably compared to five well-established climate models. Internal variations of the global mean surface temperature in the model are consistent with observed fluctuations and suggest that the recent warming slowdown can be explained as a once-in-one-hundred-years event caused by internal climate variability; periods of strong cooling in the model (‘hiatus’ analogs) are mainly associated with ENSO-related variability and to a lesser degree also to PDO shifts, with the AMO playing a minor role. Common atmospheric and oceanic variability patterns are simulated largely consistent with their real counterparts. Typical deficits also found in other models at similar resolutions remain, in particular too weak non-seasonal variability of SSTs over large parts of the ocean and episodic periods of almost absent deep-water formation in the Labrador Sea, resulting in overestimated North Atlantic SST variability. Concerning the influence of locally (isotropically) increased resolution, the ENSO pattern and index statistics improve significantly with higher resolution around the equator, illustrating the potential of the novel unstructured-mesh method for global climate modeling.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-016-3192-6
DO – 10.1007/s00382-016-3192-6
ID – Rackow2016
ER –

NR – 83
TY – JOUR
AU – Chen, Xianyao
AU – Tung, Ka-Kit
TI – Correspondence: Variations in ocean heat uptake during the surface warming hiatus
JO – Nature Communications
PY – 2016/08/19/online
VL – 7
SP – 12541
PB – The Author(s)
UR – http://dx.doi.org/10.1038/ncomms12541
DO – 10.1038/ncomms12541
M3 – Correspondence
ER –

NR – 84
TY – JOUR
T1 – Estimation of subsurface temperature anomaly in the Indian Ocean during recent global surface warming hiatus from satellite measurements: A support vector machine approach
AU – Su, Hua
AU – Wu, Xiangbai
AU – Yan, Xiao-Hai
AU – Kidwell, Autumn
JO – Remote Sensing of Environment
VL – 160
SP – 63
EP – 71
PY – 2015
DA – 2015/04/01/
SN – 0034-4257
DO – https://doi.org/10.1016/j.rse.2015.01.001
UR – http://www.sciencedirect.com/science/article/pii/S0034425715000103
KW – Subsurface temperature anomaly
KW – Satellite measurements
KW – Support vector machine
KW – The Indian Ocean
KW – Global warming hiatus
AB – Estimating the thermal information in the subsurface and deeper ocean from satellite measurements over large basin-wide scale is important but also challenging. This paper proposes a support vector machine (SVM) method to estimate subsurface temperature anomaly (STA) in the Indian Ocean from a suite of satellite remote sensing measurements including sea surface temperature anomaly (SSTA), sea surface height anomaly (SSHA), and sea surface salinity anomaly (SSSA). The SVM estimation of STA features the inclusion of in-situ Argo STA data for training and testing. SVM, one of the most popular machine learning methods, can well estimate the STA in the upper 1000m of the Indian Ocean from satellite measurements of sea surface parameters (SSTA, SSHA and SSSA as input attributes for SVM). The results, based on the common SVM application of Support Vector Regression (SVR), were validated for accuracy and reliability using the Argo STA data. Both MSE and r2 for performance measures are improved after including SSSA for SVR (MSE decreased by 12% and r2 increased by 11% on average). The results showed that SSSA, in addition to SSTA and SSHA, is a useful parameter that can help detect and describe the deeper ocean thermal structure, as well as improve the STA estimation accuracy. Moreover, our method can provide a useful technique for studying subsurface and deeper ocean thermal variability which has played an important role in recent global surface warming hiatus since 1998, from satellite measurements in large basin-wide scale.
ER –

NR – 85
TY – JOUR
AU – Yeo, Sae-Rim
AU – Yeh, Sang-Wook
AU – Kim, Kwang-Yul
AU – Kim, WonMoo
PY – 2017
DA – 2017/08/01
TI – The role of low-frequency variation in the manifestation of warming trend and ENSO amplitude
JO – Climate Dynamics
SP – 1197
EP – 1213
VL – 49
IS – 4
AB – Despite the increase in greenhouse gas concentration, the sea surface temperature (SST) over the tropical eastern Pacific during the period of 1999–2014 exhibits less warming trend compared to the earlier decades. It has been noted that this warming hiatus is accompanied by a negative phase of the Pacific Decadal Oscillation (PDO), which represents low-frequency variability over the Pacific. On the other hand, the 2015/2016 El Niño is among the strongest comparable to the 1997/1998 event, which coincides with the recently altered PDO phase from negative to positive. These observational evidences have generated substantial interest in the role of low-frequency variations in modulating El Niño-Southern Oscillation amplitude as well as manifestation of warming signal in the tropical Pacific. Therefore, it is necessary to appropriately separate low-frequency variability and global warming signal from SST records. Here, we present three primary modes of global SST that include secular warming trend, low-frequency variability, and biennial oscillation. Based on the independent behavior of these three modes, global warming is clearly continuing but its manifestation is enhanced (depressed) when the low-frequency variation is in the positive (negative) phase. Further, possibility of strong El Niño increases under the positive phase of the low-frequency mode, which amplifies warming over the tropical eastern Pacific. Indeed, the strong 2015/2016 El Niño is largely attributed to the positive phase of the low-frequency mode. In order to examine the climate models’ ability to simulate the three SST modes as obtained in the observational record, the Coupled Model Intercomparison Project phase 5 (CMIP5) datasets are also analyzed. The spatial and temporal characteristics of the three modes have been replicated closely by the selected CMIP5 models forced by the historical condition, which provides an analogy of the interplay of three modes in the observed tropical Pacific SST.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-016-3376-0
DO – 10.1007/s00382-016-3376-0
ID – Yeo2017
ER –

NR – 86
TY – JOUR
AU – Li, Chao
AU – Stevens, Bjorn
AU – Marotzke, Jochem
C8 – 2015GL065327
TI – Eurasian winter cooling in the warming hiatus of 1998–2012
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 42
IS – 19
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2015GL065327
DO – 10.1002/2015GL065327
SP – 8131
EP – 8139
KW – warming hiatus
KW – winter cooling
KW – 0350 Pressure, density, and temperature
KW – 1610 Atmosphere
KW – 1616 Climate variability
PY – 2015
AB – We investigate the relative magnitudes of the contributions of surface temperature trends from different latitude bands to the recent warming hiatus. We confirm from five different global data sets that the global-mean surface temperature trend in the period 1998–2012 is strongly influenced by a pronounced Eurasian winter cooling trend. To understand the drivers of this winter cooling trend, we perform three 20-member ensembles of simulations with different prescribed sea surface temperature and sea ice in the atmospheric model ECHAM6. Our experimental results suggest that the Arctic sea ice loss does not drive systematic changes in the Northern Hemisphere large-scale circulation in the past decades. The observed Eurasian winter cooling trend over 1998–2012 arises essentially from atmospheric internal variability and constitutes an extreme climate event. However, the observed reduction in Arctic sea ice enhances the variability of Eurasian winter climate and thus increases the probability of an extreme Eurasian winter cooling trend.
ER –

NR – 87
TY – JOUR
AU – Parker, Albert
PY – 2014
TI – The “Present Global Warming Hiatus” Is Part Of A Quasi-60 Years Oscillation In The Worldwide Average Temperatures In The Downwards Phase
JO – Environmental Science : An Indian Journal
VL – 9
IS – 1
SP – 14
EP – 22
UR – http://www.tsijournals.com/abstract/the-present-global-warming-hiatus-is-part-of-a-quasi60-years-oscillation-in-the-worldwide-average-temperatures-in-the-do-2828.html
AB – Since the beginning of this century, the seas have not been warming over the surface as well as in the layers up to 2000mdepth, asmeasured in theARGO project. Over the same period, the reconstructed land and sea temperatures of the HADCRUT4, GISS and NCDCdata sets have been warming marginally, mostly because of the largest opportunities to introduce upward biases in a less accurate mixed computational and experimental result. Over the same period of time, the CMIP3 and CMIP5 have predicted huge warmings that have no support in themeasurements or reconstructions. It is shown here that the Â?present global warming hiatusÂ? is possibly a repetition of a dwelling period of not significant warming that the reconstructions locate from1945 to 1975.
ER –

NR – 88
TY – JOUR
AU – Xie, Yongkun
AU – Huang, Jianping
AU – Liu, Yuzhi
TI – From accelerated warming to warming hiatus in China
JO – International Journal of Climatology
JA – Int. J. Climatol.
VL – 37
IS – 4
PB – John Wiley & Sons, Ltd
SN – 1097-0088
UR – http://dx.doi.org/10.1002/joc.4809
DO – 10.1002/joc.4809
SP – 1758
EP – 1773
KW – warming hiatus
KW – accelerated warming
KW – cold weather events
KW – decadal variability
KW – atmospheric circulation
PY – 2017
AB – As the recent global warming hiatus has attracted worldwide attention, we examined the robustness of the warming hiatus in China and the related dynamical mechanisms in this study. Based on the results confirmed by the multiple data and trend analysis methods, we found that the annual mean temperature in China had a cooling trend during the recent global warming hiatus period, which suggested a robust warming hiatus in China. The warming hiatus in China was dominated by the cooling trend in the cold season, which was mainly induced by the more frequent and enhanced extreme-cold events. By examining the variability of the temperature over different time scales, we found the recent warming hiatus was mainly associated with a downward change of decadal variability, which counteracted the background warming trend. Decadal variability was also much greater in the cold season than in the warm season, and also contributed the most to the previous accelerated warming. We found that the previous accelerated warming and the recent warming hiatus, and the decadal variability of temperature in China were connected to changes in atmospheric circulation. There were opposite circulation changes during these two periods. The westerly winds from the low to the high troposphere over the north of China all enhanced during the previous accelerated warming period, while it weakened during the recent hiatus. The enhanced westerly winds suppressed the invasion of cold air from the Arctic and vice versa. Less frequent atmospheric blocking during the accelerated warming period and more frequent blocking during the recent warming hiatus confirmed this hypothesis. Furthermore, variation in the Siberian High and East Asian winter monsoon season supports the given conclusions.
ER –

NR – 89
TY – JOUR
T1 – Why Has the Relationship between Indian and Pacific Ocean Decadal Variability Changed in Recent Decades?
AU – Dong, Lu
AU – McPhaden, Michael J.
Y1 – 2016/12/14
PY – 2016
DA – 2017/03/01
N1 – doi: 10.1175/JCLI-D-16-0313.1
DO – 10.1175/JCLI-D-16-0313.1
T2 – Journal of Climate
JF – Journal of Climate
JO – J. Climate
SP – 1971
EP – 1983
VL – 30
IS – 6
PB – American Meteorological Society
AB – Both the Indian and Pacific Oceans exhibit prominent decadal time scale variations in sea surface temperature (SST), linked dynamically via atmospheric and oceanic processes. However, the relationship between SST in these two basins underwent a dramatic transformation beginning around 1985. Prior to that, SST variations associated with the Indian Ocean basin mode (IOB) and the interdecadal Pacific oscillation (IPO) were positively correlated, whereas afterward they were much less clearly synchronized. Evidence is presented from both observations and coupled state-of-the-art climate models that enhanced external forcing, particularly from increased anthropogenic greenhouse gases, was the principal cause of this changed relationship. Using coupled climate model experiments, it is shown that without external forcing, the evolution of the IOB would be strongly forced by variations in the IPO. However, with strong external forcing, the dynamical linkage between the IOB and the IPO weakens so that the negative phase IPO after 2000 is unable to force a negative phase IOB-induced cooling of the Indian Ocean. This changed relationship in the IOB and IPO led to unique SST patterns in the Indo-Pacific region after 2000, which favored exceptionally strong easterly trade winds over the tropical Pacific Ocean and a pronounced global warming hiatus in the first decade of the twenty-first century.
SN – 0894-8755
M3 – doi: 10.1175/JCLI-D-16-0313.1
UR – https://doi.org/10.1175/JCLI-D-16-0313.1
Y2 – 2018/02/19
ER –

NR – 90
TY – JOUR
AU – Desbruyères, D. G.
AU – McDonagh, E. L.
AU – King, B. A.
AU – Garry, F. K.
AU – Blaker, A. T.
AU – Moat, B. I.
AU – Mercier, H.
TI – Full-depth temperature trends in the northeastern Atlantic through the early 21st century
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 22
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL061844
DO – 10.1002/2014GL061844
SP – 7971
EP – 7979
KW – North Atlantic
KW – temperature
KW – observations
KW – hiatus
KW – 1635 Oceans
KW – 4215 Climate and interannual variability
KW – 4283 Water masses
KW – 4262 Ocean observing systems
KW – 4513 Decadal ocean variability
PY – 2014
AB – The vertical structure of temperature trends in the northeastern Atlantic (NEA) is investigated using a blend of Argo and hydrography data. The representativeness of sparse hydrography sampling in the basin mean is assessed using a numerical model. Between 2003 and 2013, the NEA underwent a strong surface cooling (0–450 m) and a significant warming at intermediate and deep levels (1000 m to 3000 m) that followed a strong cooling trend observed between 1988 and 2003. During 2003–2013, gyre-specific changes are found in the upper 1000 m (warming and cooling of the subtropical and subpolar gyres, respectively), while the intermediate and deep warming primarily occurred in the subpolar gyre, with important contributions from isopycnal heave and water mass property changes. The full-depth temperature change requires a local downward heat flux of 0.53 ± 0.06 W m-2 through the sea surface, and its vertical distribution highlights the likely important role of the NEA in the recent global warming hiatus.
ER –

NR – 91
TY – JOUR
AU – Chakrabarty, D. K.
AU – Peshin, S. K.
PY – 2013
TI – Global warming and solar anomaly
JO – Indian Journal of Radio & Space Physics
VL – 42
IS – 6
UR – http://op.niscair.res.in/index.php/IJRSP/article/view/2251
AB – During 2002-2008, there was no increase in global temperature, though green house gas concentrations had increased. Sun is the ultimate source of energy. It has been, therefore, examined if there was any anomaly in the solar characteristics during this period. The sunspot number data has been used for this purpose. This parameter has an 11-year solar activity cycle and the same is found in the global temperature. But the trend in sun’s output, after removing solar activity effect, does not match with the long term trend of global temperature. Peculiarities in the duration and in the peak value of solar cycle 23 were identified which might have portended the increase of global temperature during 2002-2008. The possibility of the pause of increase in temperature could also be that the heat generated due to the increase in the greenhouse gas concentration was absorbed in deep ocean layer.
ER –

NR – 92
TY – JOUR
AU – Zeng, Xubin
AU – Geil, Kerrie
C8 – 2016GL071035
TI – Global warming projection in the 21st century based on an observational data-driven model
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 43
IS – 20
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2016GL071035
DO – 10.1002/2016GL071035
SP – 10,947
EP – 10,954
KW – global warming projection
KW – decadal prediction
KW – observation-based model
KW – decadal hincast
KW – 1922 Forecasting
KW – 1990 Uncertainty
KW – 3305 Climate change and variability
KW – 3320 Idealized model
PY – 2016
AB – Global warming has been projected primarily by Earth system models (ESMs). Complementary to this approach, here we provide the decadal and long-term global warming projections based on an observational data-driven model. This model combines natural multidecadal variability with anthropogenic warming that depends on the history of annual emissions. It shows good skill in decadal hindcasts with the recent warming slowdown well captured. While our ensemble mean temperature projections at the end of 21st century are consistent with those from ESMs, our decadal warming projection of 0.35 (0.30-0.43)?K from 1986–2005 to 2016–2035 is within their projection range and only two-thirds of the ensemble mean from ESMs. Our predicted warming rate in the next few years is slower than in the 1980s and 1990s, followed by a greater warming rate. Our projection uncertainty range is just one-third of that from ESMs, and its implication is also discussed.
ER –

NR – 93
TY – JOUR
AU – Leggett, L. M. W.
AU – Ball, D. A.
PY – 2015
TI – Granger causality from changes in level of atmospheric CO2 to global surface temperature and the El Niño–Southern Oscillation, and a candidate mechanism in global photosynthesis
JO – Atmospheric Chemistry and Physics
VL – 15
SP – 11571
EP – 11592
UR – http://dx.doi.org/10.5194/acp-15-11571-2015
DO – 10.5194/acp-15-11571-2015
AB – A significant difference, now of some 16 years’ duration, has been shown to exist between the observed global surface temperature trend and that expected from the majority of climate simulations. For its own sake, and to enable better climate prediction for policy use, the reasons behind this mismatch need to be better understood. While an increasing number of possible causes have been proposed, the candidate causes have not yet converged. With this background, this paper reinvestigates the relationship between change in the level of CO2 and two of the major climate variables, atmospheric temperature and the El Niño–Southern Oscillation (ENSO). Using time-series analysis in the form of dynamic regression modelling with autocorrelation correction, it is shown that first-difference CO2 leads temperature and that there is a highly statistically significant correlation between first-difference CO2 and temperature. Further, a correlation is found for second-difference CO2 with the Southern Oscillation Index, the atmospheric-pressure component of ENSO. This paper also shows that both these correlations display Granger causality. It is shown that the first-difference CO2 and temperature model shows no trend mismatch in recent years. These results may contribute to the prediction of future trends for global temperature and ENSO. Interannual variability in the growth rate of atmospheric CO2 is standardly attributed to variability in the carbon sink capacity of the terrestrial biosphere. The terrestrial biosphere carbon sink is created by the difference between photosynthesis and respiration (net primary productivity): a major way of measuring global terrestrial photosynthesis is by means of satellite measurements of vegetation reflectance, such as the Normalized Difference Vegetation Index (NDVI). In a preliminary analysis, this study finds a close correlation between an increasing NDVI and the increasing climate model/temperature mismatch (as quantified by the difference between the trend in the level of CO2 and the trend in temperature).
ER –

NR – 94
TY – JOUR
AU – Ducic, Vladan
AU – Milenkovic, Milan
AU – Milijaševic, Dragana
AU – Vujacic, Duško
AU – Bjeljac, Željko
AU – Lovic, Suzana
AU – Gajic, Mirjana
AU – Andelkovic, Goran
AU – Djordjevic, Aleksandar
PY – 2015
TI – Hiatus in global warming – example of water temperature of the Danube River at Bogojevo gauge (Serbia)
JO – Thermal Science
VL – 19
IS – 2
SP – 467
EP – 476
DO – 10.2298/TSCI150430133D
UR – http://dx.doi.org/10.2298/TSCI150430133D
AB – The research included trends in water temperature of the Danube River at Bogojevo gauge and surface air temperature at the nearby meteorological station Sombor, as well as an analysis of the results obtained in relation to the claims of the existence of the hiatus in global air temperature increase in the period 1998-2012. In the period 1961-2013, there was a statistically significant increase in the mean annual water temperature (0.039°C/year), as well as all the average monthly values. However, with annual values for the period 1998-2013, there was a decrease. The longest periods of negative trend (27 years) were recorded for January and February. A high correlation was found between the surface air temperature and water temperature for all monthly and seasonal values. In the mean annual air temperature the presence of the hiatus is not observed, but a negative trend is recorded in March (32 years), December (43 years) and February (49 years). The highest correlations between water temperature and North Atlantic Oscillation (NAO), Arctic Oscillation (AO) and Atlantic Multidecadal Oscillation (AMO) were obtained for the NAO in January (0.60), the AMO in autumn (0.52) and the NAO in winter (0.51). For surface air temperature, the highest correlations were registered for the AMO in summer (0.49) and the NAO in winter (0.42). The results indicate the dominant role of natural factors in the decrease of winter air temperature and water temperature of the Danube.
ER –

NR – 95
TY – JOUR
AU – Gettelman, A.
AU – Shindell, D. T.
AU – Lamarque, J. F.
PY – 2015
DA – 2015/10/01
TI – Impact of aerosol radiative effects on 2000–2010 surface temperatures
JO – Climate Dynamics
SP – 2165
EP – 2179
VL – 45
IS – 7
AB – Aerosol radiative forcing from direct and indirect effects of aerosols is examined over the recent past (last 10–15 years) using updated sulfate aerosol emissions in two Earth System Models with very different surface temperature responses to aerosol forcing. The hypothesis is that aerosol forcing and in particular, the impact of indirect effects of aerosols on clouds (Aerosol–Cloud Interactions, or ACI), explains the recent ‘hiatus’ in global mean surface temperature increases. Sulfate aerosol emissions increase globally from 2000 to 2005, and then decrease slightly to 2010. Thus the change in anthropogenic sulfate induced net global radiative forcing is small over the period. Regionally, there are statistically significant forcings that are similar in both models, and consistent with changes in simulated emissions and aerosol optical depth. Coupled model simulations are performed to look at impacts of the forcing on recent surface temperatures. Temperature response patterns in the models are similar, and reflect the regional radiative forcing. Pattern correlations indicate significant correlations between observed decadal surface temperature changes and simulated surface temperature changes from recent sulfate aerosol forcing in an equilibrium framework. Sulfate ACI might be a contributor to the spatial patterns of recent temperature forcing, but not to the global mean ‘hiatus’ itself.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-014-2464-2
DO – 10.1007/s00382-014-2464-2
ID – Gettelman2015
ER –

NR – 96
TY – JOUR
AU – Kuntz, L. B.
AU – Schrag, D. P.
C8 – 2016JD025430
TI – Impact of Asian aerosol forcing on tropical Pacific circulation and the relationship to global temperature trends
JO – Journal of Geophysical Research: Atmospheres
JA – J. Geophys. Res. Atmos.
VL – 121
IS – 24
SN – 2169-8996
UR – http://dx.doi.org/10.1002/2016JD025430
DO – 10.1002/2016JD025430
SP – 14,403
EP – 14,413
KW – Asian aerosol
KW – atmospheric circulation
KW – temperature trends
KW – 0305 Aerosols and particles
KW – 1620 Climate dynamics
KW – 3305 Climate change and variability
KW – 3337 Global climate models
PY – 2016
AB – The recent slowdown in the warming of global surface temperatures has been linked to the enhancement of trade winds in the central equatorial Pacific. The possible role of Asian aerosol emissions in forcing these wind anomalies is investigated through a series of idealized model simulations. Circulation patterns in response to localized negative radiative perturbations, indicative of aerosol effects, are investigated for both a slab and an active ocean models. The results suggest that Asian aerosols cannot explain the recent intensification of trade wind anomalies in the equatorial Pacific.
ER –

NR – 97
TY – JOUR
AU – Meehl, Gerald A.
AU – Hu, Aixue
AU – Teng, Haiyan
TI – Initialized decadal prediction for transition to positive phase of the Interdecadal Pacific Oscillation
JO – Nature Communications
PY – 2016/06/02/online
VL – 7
SP – 11718
PB – The Author(s)
UR – http://dx.doi.org/10.1038/ncomms11718
DO – 10.1038/ncomms11718
M3 – Article
AB – The negative phase of the Interdecadal Pacific Oscillation (IPO), a dominant mode of multi-decadal variability of sea surface temperatures (SSTs) in the Pacific, contributed to the reduced rate of global surface temperature warming in the early 2000s. A proposed mechanism for IPO multidecadal variability indicates that the presence of decadal timescale upper ocean heat content in the off-equatorial western tropical Pacific can provide conditions for an interannual El Niño/Southern Oscillation event to trigger a transition of tropical Pacific SSTs to the opposite IPO phase. Here we show that a decadal prediction initialized in 2013 simulates predicted Niño3.4 SSTs that have qualitatively tracked the observations through 2015. The year three to seven average prediction (2015–2019) from the 2013 initial state shows a transition to the positive phase of the IPO from the previous negative phase and a resumption of larger rates of global warming over the 2013–2022 period consistent with a positive IPO phase.
ER –

NR – 98
TY – JOUR
T1 – Interhemispheric SST Gradient Trends in the Indian Ocean prior to and during the Recent Global Warming Hiatus
AU – Dong, Lu
AU – McPhaden, Michael J.
Y1 – 2016/09/14
PY – 2016
DA – 2016/12/01
N1 – doi: 10.1175/JCLI-D-16-0130.1
DO – 10.1175/JCLI-D-16-0130.1
T2 – Journal of Climate
JF – Journal of Climate
JO – J. Climate
SP – 9077
EP – 9095
VL – 29
IS – 24
PB – American Meteorological Society
AB – Sea surface temperatures (SSTs) have been rising for decades in the Indian Ocean in response to greenhouse gas forcing. However, this study shows that during the recent hiatus in global warming, a striking interhemispheric gradient in Indian Ocean SST trends developed around 2000, with relatively weak or little warming to the north of 10°S and accelerated warming to the south of 10°S. Evidence is presented from a wide variety of data sources showing that this interhemispheric gradient in SST trends is forced primarily by an increase of Indonesian Throughflow (ITF) transport from the Pacific into the Indian Ocean induced by stronger Pacific trade winds. This increased transport led to a depression of the thermocline that facilitated SST warming, presumably through a reduction in the vertical turbulent transport of heat in the southern Indian Ocean. Surface wind changes in the Indian Ocean linked to the enhanced Walker circulation also may have contributed to thermocline depth variations and associated SST changes, with downwelling-favorable wind stress curls between 10° and 20°S and upwelling-favorable wind stress curls between the equator and 10°S. In addition, the anomalous southwesterly wind stresses off the coast of Somalia favored intensified coastal upwelling and offshore advection of upwelled water, which would have led to reduced warming of the northern Indian Ocean. Although highly uncertain, lateral heat advection associated with the ITF and surface heat fluxes may also have played a role in forming the interhemispheric SST gradient change.
SN – 0894-8755
M3 – doi: 10.1175/JCLI-D-16-0130.1
UR – https://doi.org/10.1175/JCLI-D-16-0130.1
Y2 – 2018/02/19
ER –

NR – 99
TY – JOUR
AU – Outten, Stephen
AU – Thorne, Peter
AU – Bethke, Ingo
AU – Seland, Øyvind
C8 – 2015JD023859
TI – Investigating the recent apparent hiatus in surface temperature increases: 1. Construction of two 30-member Earth System Model ensembles
JO – Journal of Geophysical Research: Atmospheres
JA – J. Geophys. Res. Atmos.
VL – 120
IS – 17
SN – 2169-8996
UR – http://dx.doi.org/10.1002/2015JD023859
DO – 10.1002/2015JD023859
SP – 8575
EP – 8596
KW – hiatus
KW – forcings
KW – GCMs
KW – temperature
KW – ensemble
KW – 0399 General or miscellaneous
KW – 1616 Climate variability
KW – 1626 Global climate models
KW – 1872 Time series analysis
PY – 2015
AB – The recent Intergovernmental Panel on Climate Change report, along with numerous studies since, has suggested that the apparent global warming hiatus results from some combination of natural variability and changes to external forcings. Herein the external forcings for greenhouse gases (GHGs), long-lived trace gases, volcanic and tropospheric aerosols, and solar irradiance have been replaced in the Norwegian Earth System Model using recent observational estimates. The potential impact of these alternative forcings, and by residual the internally generated variability, is examined through two 30-member ensembles covering the period 1980 to 2012. The Reference ensemble uses the Coupled Model Intercomparison Project phase 5 historical forcings extended with the Representative Concentration Pathway 8.5 (RCP8.5) scenario, while the Sensitivity ensemble uses the alternative forcings. Over the hiatus period defined herein as 1998–2012, all of the forcings show some change between the Sensitivity and Reference experiments and have a combined net forcing change of -0.03?W?m-2. The GHG forcing is 0.012?W?m-2 higher in the Sensitivity forcings. The alternative solar forcing differs from the Reference forcing by -0.08?W?m-2, the same as the alternative volcanic forcing that was based on the latest estimates from NASA Goddard Institute for Space Studies. Anthropogenic aerosol emissions were replaced using the EU-EclipseV4a data set and produce a mean forcing change of 0.11?W?m-2 over the period. Part 1 details the creation of the two 30-member ensembles and their characterization for parameters of particular relevance to the explanation of the hiatus. A detailed investigation of the two resulting ensembles global surface temperature behavior is given in Part 2, along with comparisons to observational data sets.
ER –

NR – 100
TY – JOUR
AU – Thorne, Peter
AU – Outten, Stephen
AU – Bethke, Ingo
AU – Seland, Øyvind
C8 – 2014JD022805
TI – Investigating the recent apparent hiatus in surface temperature increases: 2. Comparison of model ensembles to observational estimates
JO – Journal of Geophysical Research: Atmospheres
JA – J. Geophys. Res. Atmos.
VL – 120
IS – 17
SN – 2169-8996
UR – http://dx.doi.org/10.1002/2014JD022805
DO – 10.1002/2014JD022805
SP – 8597
EP – 8620
KW – hiatus
KW – forcings
KW – GCM
KW – ensemble
KW – temperature
KW – 0305 Aerosols and particles
KW – 0325 Evolution of the atmosphere
KW – 1615 Biogeochemical cycles, processes, and modeling
KW – 1626 Global climate models
KW – 1622 Earth system modeling
PY – 2015
AB – To assess published hypotheses surrounding the recent slowdown in surface warming (hiatus), we compare five available global observational surface temperature estimates to two 30-member ensembles from the Norwegian Earth System Model (NorESM). Model ensembles are initialized in 1980 from the transient historical runs and driven with forcings used in the CMIP5 experiments and updated forcings based upon current observational understanding, described in Part 1. The ensembles’ surface temperature trends are statistically indistinguishable over 1998–2012 despite differences in the prescribed forcings. There is thus no evidence that forcing errors play a significant role in explaining the hiatus according to NorESM. The observations fall either toward the lower portion of the ensembles or, for some observational estimates and regions, outside. The exception is the Arctic where the observations fall toward the upper ensemble bounds. Observational data set choices can make a large difference to findings of consistency or otherwise. Those NorESM ensemble members that exhibit Nino3.4 Sea Surface Temperature (SST) trends similar to observed also exhibit comparable tropical and to some extent global mean trends, supporting a role for El Nino Southern Oscillation in explaining the hiatus. Several ensemble members capture the marked seasonality observed in Northern Hemisphere midlatitude trends, with cooling in the wintertime and warming in the remaining seasons. Overall, we find that we cannot falsify NorESM as being capable of explaining the observed hiatus behavior. Importantly, this is not equivalent to concluding NorESM could simultaneously capture all important facets of the hiatus. Similar experiments with further, distinct, Earth System Models are required to verify our findings.
ER –

NR – 101
TY – JOUR
AU – Fyfe, John C.
AU – Meehl, Gerald A.
AU – England, Matthew H.
AU – Mann, Michael E.
AU – Santer, Benjamin D.
AU – Flato, Gregory M.
AU – Hawkins, Ed
AU – Gillett, Nathan P.
AU – Xie, Shang-Ping
AU – Kosaka, Yu
AU – Swart, Neil C.
TI – Making sense of the early-2000s warming slowdown
JA – Nature Climate Change
PY – 2016/02/24/online
VL – 6
SP – 224
PB – Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
UR – http://dx.doi.org/10.1038/nclimate2938
L3 – 10.1038/nclimate2938
AB – It has been claimed that the early-2000s global warming slowdown or hiatus, characterized by a reduced rate of global surface warming, has been overstated, lacks sound scientific basis, or is unsupported by observations. The evidence presented here contradicts these claims.
ER –

NR – 102
TY – JOUR
AU – Boykoff, Maxwell T.
TI – Media discourse on the climate slowdown
JA – Nature Climate Change
PY – 2014/02/26/online
VL – 4
SP – 156
PB – Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
UR – http://dx.doi.org/10.1038/nclimate2156
L3 – 10.1038/nclimate2156
AB – We must not fall victim to decontextualized and ahistorical media accounting of climate trends.
ER –

NR – 103
TY – JOUR
AU – Somavilla, R.
AU – González-Pola, C.
AU – Schauer, U.
AU – Budéus, G.
C8 – 2015GL067254
TI – Mid-2000s North Atlantic shift: Heat budget and circulation changes
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 43
IS – 5
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2015GL067254
DO – 10.1002/2015GL067254
SP – 2059
EP – 2068
KW – North Atlantic
KW – ocean heat content
KW – circulation
KW – modal waters
KW – deep convection
KW – hiatus
KW – 4215 Climate and interannual variability
KW – 4283 Water masses
KW – 4532 General circulation
KW – 4572 Upper ocean and mixed layer processes
PY – 2016
AB – Prior to the 2000s, the North Atlantic was the basin showing the greatest warming. However, since the mid-2000s during the so-called global warming hiatus, large amounts of heat were transferred in this basin from upper to deeper levels while the dominance in terms of atmospheric heat capture moved into the Indo-Pacific. Here we show that a large transformation of modal waters in the eastern North Atlantic (ENA) played a crucial role in such contrasting behavior. First, strong winter mixing in 2005 transformed ENA modal waters into a much saltier, warmer, and denser variety, transferring upper ocean heat and salt gained slowly over time to deeper layers. The new denser waters also altered the zonal dynamic height gradient reversing the southward regional flow and enhancing the access of saltier southern waters to higher latitudes. Then, the excess salinity in northern regions favored additional heat injection through deep convection events in later years.
ER –

NR – 104
TY – JOUR
T1 – Periodicities in mean sea-level fluctuations and climate change proxies: Lessons from the modelling for coastal management
AU – Baker, R.G.V.
AU – McGowan, S.A.
JO – Ocean & Coastal Management
VL – 98
SP – 187
EP – 201
PY – 2014
DA – 2014/09/01/
SN – 0964-5691
DO – https://doi.org/10.1016/j.ocecoaman.2014.05.027
UR – http://www.sciencedirect.com/science/article/pii/S0964569114001781
AB – The question of whether sea levels and global temperatures are accelerating or decelerating is a major source of current debate. Single taper and multi-taper spectral analysis from seventeen globally distributed tidal stations and twenty climate proxies show aggregate significant common periodicities in mean sea level fluctuations and the climate proxies of approximately 7 yr, 13 yr, 23 yr, 32 yr, 41 yr, 53 yr, 66 yr, 88 yr, 105 yr and 132 yr, respectively. These periods are shown to strongly correlate with an harmonic sequence of n, m = n + n/4 and p = n + n/2n for n = 5.5 yr and this synchronicity allows for a climate state function to be defined by Lotka–Volterra limit cycles. Such a model can include both anthropogenic warming and complex natural cycles, based on past evidence, and these cycles can form or bifurcate into extreme events close to critical values. The model suggests that accelerating sea levels can be in-phase, but lag decelerating global temperatures or vice versa, so a ‘pause’ in global warming should not be surprising. Further, the model can simulate the uneven regional effect of climate responses and replicate the chaos apparent in monthly sea-level records. The approach poses ‘a planner’s dilemma’ whereby the likelihood of a present 1 in 100 yr positive extreme event can either be caused by anthropogenic warming within shorter cycles or by a stationary mean in a longer cycle. We simply show that for rising average temperatures in a double period cascading model, there would be a three-fold increase in the likelihood of an equivalent 1 in 100 yr positive extreme event relative to present over a 20 yr period. A consequence to the ‘planner’s dilemma’ is the ‘manager’s risk imperative’ where risk cycles can be quantified into strategic GIS maps of potential future inundations: identifying vulnerability, defining possible economic impacts and underpinning response strategies that are legally defensible and transparent to a range of stakeholders.
ER –

NR – 105
TY – JOUR
AU – Morrison, Kyle W.
AU – Battley, Phil F.
AU – Sagar, Paul M.
AU – Thompson, David R.
PY – 2015
DA – 2015/02/01
TI – Population dynamics of Eastern Rockhopper Penguins on Campbell Island in relation to sea surface temperature 1942–2012: current warming hiatus pauses a long-term decline
JO – Polar Biology
SP – 163
EP – 177
VL – 38
IS – 2
AB – Major population changes of marine mega-fauna are ongoing as global warming, and other anthropogenic drivers affect prey availability. The historical stronghold of the Eastern Rockhopper Penguin (Eudyptes chrysocome filholi) was New Zealand’s sub-Antarctic Campbell Island, but the population declined by 94 % between 1942 and 1984. The apparent mechanism of collapse was warm ocean temperatures causing an inadequate food supply. Eudyptes penguin population declines are ongoing at some breeding sites, highlighting the need to investigate the population trend on Campbell Island since 1984. We estimated the Eastern Rockhopper Penguin breeding population size through physical and photo-counts of birds and nests in 2012, and changes in colony area relative to 1984 and 1996 photographs. We estimated the 2012 population size at 33,239 breeding pairs, a 21.8 % decrease from an (adjusted) estimate of 42,528 pairs in 1984. Although substantial, the recent 1984–2012 decline occurred at a much slower rate (? = 0.991) than the 1942–1984 decline (? = 0.940). Despite great variation in trends between colonies ostensibly linked to differences in predation rates, the recent decline occurred primarily between 1984 and 1996, and thereafter the overall population grew. A 100-year time series of extended reconstructed sea surface temperatures (ERSST) confirmed that the population declined during warm periods and increased during cool periods, but that the initial decline began before increases in regional ERSST. Population growth after 1996 appears related to the current global warming hiatus, lower ERSST, and increased abundance of a key prey species. We predict a continuation of the long-term population decline after warming resumes.
SN – 1432-2056
UR – https://doi.org/10.1007/s00300-014-1575-x
DO – 10.1007/s00300-014-1575-x
ID – Morrison2015
ER –

NR – 106
TY – JOUR
DB – PMC
AU – An, Wenling
AU – Hou, Shugui
AU – Zhang, Wangbin
AU – Wu, Shuangye
AU – Xu, Hao
AU – Pang, Hongxi
AU – Wang, Yetang
AU – Liu, Yaping
T1 – Possible recent warming hiatus on the northwestern Tibetan Plateau derived from ice core records
SN – 2045-2322
Y1 – 2016
PY – 2016/09/09
PY – 2016/04/06/received
PY – 2016/08/16/accepted
AB – Many studies have reported enhanced warming trend on the Tibetan Plateau (TP), even during the warming hiatus period. However, most of these studies are based on instrumental data largely collected from the eastern TP, whereas the temperature trend over the extensive northwestern TP remains uncertain due to few meteorological stations. Here we combined the stable isotopic d(18)O record of an ice core recovered in 2012 from the Chongce glacier with the d(18)O records of two other ice cores (i.e., Muztagata and Zangser Kangri) in the same region to establish a regional temperature series for the northwestern TP. The reconstruction shows a significant warming trend with a rate of 0.74?±?0.12?°C/decade for the period 1970–2000, but a decreasing trend from 2001 to 2012. This is consistent with the reduction of warming rates during the recent decade observed at the only two meteorological stations on the northwestern TP, even though most stations on the eastern TP have shown persistent warming during the same period. Our results suggest a possible recent warming hiatus on the northwestern TP. This could have contributed to the relatively stable status of glaciers in this region.
SP – 32813
VL – 6
DO – 10.1038/srep32813
AN – PMC5017263
UR – http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5017263/
U1 – 27612305[pmid]
J1 – Sci Rep
JF – Scientific Reports
PB – Nature Publishing Group
ER –

NR – 107
TY – JOUR
T1 – Present contributions to sea level rise by thermal expansion and ice melting and implication on coastal management
AU – Parker, Albert
JO – Ocean & Coastal Management
VL – 98
SP – 202
EP – 211
PY – 2014
DA – 2014/09/01/
SN – 0964-5691
DO – https://doi.org/10.1016/j.ocecoaman.2014.05.026
UR – http://www.sciencedirect.com/science/article/pii/S0964569114001744
AB – Increasing ocean heat content has been suggested on the basis of theories. Reconstructions (modelling results based on selected scattered measurements) and simulations (modelling results not based on observations) have both shown a significant warming since the year 1970 that increased at an ever faster rate over the 14 years this century. It is shown here that, contrary to this claim, the detailed measurements of the ocean temperature and salinity by the sampling buoys of the ARGO project show only minor changes of temperature and salinity since the early 2000s. The ARGO results cover the ocean layers 0–2000m except for the North and South Poles. The satellite NSSTC surface air temperature measurements over the world oceans show a global cooling over the last 11 years, and the satellite NSDIC sea ice extent measurements show globally increasing ice coverage over the North and South Poles. The North Pole sea ice is certainly reducing, but over the last 11 years the growth of the South Pole sea ice has more than compensated that loss. The true measurements are in marked contrast to theoretical reconstructions and simulations. This result has a huge implication on coastal management that should be based on observationally derived forecasts rather than “projections” of models lacking validation.
ER –

NR – 108
TY – JOUR
T1 – Recent hiatus caused by decadal shift in Indo-Pacific heating
JF – Science
JO – Science
SP – 532
LP – 535
M3 – 10.1126/science.aaa4521
VL – 349
IS – 6247
AU – Nieves, Veronica
AU – Willis, Josh K.
AU – Patzert, William C.
Y1 – 2015/07/31
UR – http://science.sciencemag.org/content/349/6247/532.abstract
AB – Global warming apparently slowed, or even stopped, during the first decade of the 21st century. This pause is commonly called the “hiatus.” We know, however, that Earth's climate system is accumulating excess solar energy owing to the build-up of greenhouse gases in the atmosphere. Where, then, has this energy gone if not into the air? Nieves et al. find that over this period, the surface Pacific Ocean has cooled but the upper Indian and Southern Oceans have warmed. Thus, the decade-long hiatus that began in 2003 would appear to be the result of a redistribution of heat within the ocean, rather than a change in the whole-Earth warming rate.Science, this issue p. 532Recent modeling studies have proposed different scenarios to explain the slowdown in surface temperature warming in the most recent decade. Some of these studies seem to support the idea of internal variability and/or rearrangement of heat between the surface and the ocean interior. Others suggest that radiative forcing might also play a role. Our examination of observational data over the past two decades shows some significant differences when compared to model results from reanalyses and provides the most definitive explanation of how the heat was redistributed. We find that cooling in the top 100-meter layer of the Pacific Ocean was mainly compensated for by warming in the 100- to 300-meter layer of the Indian and Pacific Oceans in the past decade since 2003.
ER –

NR – 109
TY – JOUR
AU – Gonzalez-Hidalgo, José Carlos
AU – Peña-Angulo, Dhais
AU – Brunetti, Michele
AU – Cortesi, Nicola
TI – Recent trend in temperature evolution in Spanish mainland (1951–2010): from warming to hiatus
JO – International Journal of Climatology
JA – Int. J. Climatol.
VL – 36
IS – 6
PB – John Wiley & Sons, Ltd
SN – 1097-0088
UR – http://dx.doi.org/10.1002/joc.4519
DO – 10.1002/joc.4519
SP – 2405
EP – 2416
KW – temperature
KW – trend
KW – hiatus
KW – Spain
PY – 2016
AB – The most recent debate on global warming focuses on the hiatus in global temperature, for which several explanations have been proposed. On the other hand, spatial variability and nonlinearity in temperature evolution has been recognized as a key point in global change analyses. In this study, we analyse the evolution of the warming rate in the Spanish mainland using the MOTEDAS data set for the last 60 years (1951–2010). Our special emphasis is on the last decades to detect and identify a possible hiatus, and to determine the effects of daytime (Tmax) and night-time (Tmin) records at annual and seasonal scale on the hiatus. Moving windows running trend analyses were applied to calculate temperature trend and significance for any temporal window from the beginning to the end of the series, ranging from 20 years to the whole series length (60 years) The results suggest that the warming rate in the Spanish mainland reached a maximum between 1970 and 1990, followed by a decrease in intensity in both Tmax and Tmin until the present. Furthermore, the decrease in the warming rate in Tmax has been higher than in Tmin for the last three decades; therefore, recent annual warming rates appears to depend more on Tmin than on Tmax. Significant trends disappear from the middle of the 1980s at any temporal window length in both Tmax and Tmin at annual and seasonal scales except in spring Tmin. Some differences among seasons are evident and, during the last few decades, the highest rates of warming are found in spring and summer, with Tmax and Tmin behaving in different ways. This study highlights how the warming rate is highly dependent on the length of the period analysed.
ER –

NR – 110
TY – JOUR
AU – Zhang, Yuanjie
AU – Gao, Zhiqiu
AU – Pan, Zaitao
AU – Li, Dan
AU – Wan, Bingcheng
C8 – 2015JD023886
TI – Record-breaking temperatures in China during the warming and recent hiatus periods
JO – Journal of Geophysical Research: Atmospheres
JA – J. Geophys. Res. Atmos.
VL – 121
IS – 1
SN – 2169-8996
UR – http://dx.doi.org/10.1002/2015JD023886
DO – 10.1002/2015JD023886
SP – 241
EP – 258
KW – record-breaking temperatures
KW – warming hiatus
KW – temperature extremes
KW – climate simulation
KW – 1637 Regional climate change
KW – 3305 Climate change and variability
KW – 3337 Global climate models
KW – 4313 Extreme events
PY – 2016
AB – The observed and modeled record-breaking temperature (RBT) frequency in China is analyzed for different segments of the period 1961–2050 including the hiatus period. It is found that significant changes in the RBT frequency occurred earlier, with greater amplitude, for daily minimum temperatures (TN) compared to maximum temperatures (TX) during the past five decades. Changes in the RBT frequency can be mostly explained by the mean warming trend, especially for TN, while in summer also slightly by variance. Moreover, mean climate change affects more the multiday mean RBT than the single-day counterpart as RBT occurrence is inversely proportional to variance that is smaller for multiday means. In the hiatus period (1998–2013), the ratios of record highs to lows in summer continue to increase in southern China primarily due to the lower frequency of record lows, since the decreasing temperature variance suppressed the increase in record highs under the summer warming. While the winter ratios decreased significantly across most of the country due to the winter cooling. Model simulations show a much smaller asymmetry of the RBT frequency between TX and TN as compared to the observations. The 28-model median overestimates the ratios for TX owning to missing the relative cooling in the “warming hole” region and is unable to reproduce the RBT characteristics in the hiatus period. Under a high-emission scenario, increasing rates of future temperature extremes are projected to accelerate with almost doubling ratio trends in the first half of 21st century compared to the historical results.
ER –

NR – 111
TY – JOUR
T1 – Revisiting the Relationship between Observed Warming and Surface Pressure in the Tibetan Plateau
AU – You, Qinglong
AU – Jiang, Zhihong
AU – Moore, G. W. K.
AU – Bao, Yuntao
AU – Kong, Lei
AU – Kang, Shichang
Y1 – 2016/11/10
PY – 2016
DA – 2017/03/01
DO – 10.1175/JCLI-D-15-0834.1
JF – Journal of Climate
JO – J. Climate
SP – 1721
EP – 1737
VL – 30
IS – 5
PB – American Meteorological Society
AB – AbstractThe Tibetan Plateau (TP) has an average elevation of over 4000 m and with its surrounding mountains is regarded as Earth?s ?third pole.? As a result of its size and height, climate change in the TP has its own unique characteristics that include a proposed positive correlation between the surface temperature and pressure. This study examines the trends and relationships between the surface pressure and temperature in the TP through the examination of monthly mean data from 71 stations during 1961?2013. On annual, seasonal, and monthly time scales, the TP exhibits a statistically significant warming trend that attains a rate of 0.30°C decade?1 for annual means over the period 1961?2013. The most pronounced warming occurs in winter, in agreement with previous studies, with evidence of acceleration in the rate after the mid-1980s and the global warming slowdown period. For the entire period of 1961?2013, the surface pressure in the TP has a positive trend of 0.08 hPa decade?1 on an annual basis, again with the largest trends occurring in winter. However, unlike what occurred with the surface temperature, the trend in surface pressure, in most cases, reversed sign after the mid-1980s. The trend in the geopotential height at 500 hPa from the National Centers for Environmental Prediction?National Center for Atmospheric Research (NCEP?NCAR) reanalysis is consistent with the observed surface pressure trends. Over the period 1961?2013, there is a seasonal shift in the nature of the relationship between the surface temperature and pressure with a negative correlation during summer and autumn, and a positive correlation during winter. This suggests that the nature of the relationship between these two climate elements reflects the changing nature of the seasonal snow cover (land surface property) and cloud in the region.
SN – 0894-8755
UR – https://doi.org/10.1175/JCLI-D-15-0834.1
Y2 – 2018/02/12
ER –

NR – 112
TY – JOUR
T1 – Revisiting Whether Recent Surface Temperature Trends Agree with the CMIP5 Ensemble
AU – Lin, Marena
AU – Huybers, Peter
Y1 – 2016/07/14
PY – 2016
DA – 2016/12/01
DO – 10.1175/JCLI-D-16-0123.1
JF – Journal of Climate
JO – J. Climate
SP – 8673
EP – 8687
VL – 29
IS – 24
PB – American Meteorological Society
AB – AbstractIn an earlier study, a weaker trend in global mean temperature over the past 15 years relative to the preceding decades was characterized as significantly lower than those contained within the phase 5 of the Coupled Model Intercomparison Project (CMIP5) ensemble. In this study, divergence between model simulations and observations is estimated using a fixed-intercept linear trend with a slope estimator that has one-third the noise variance compared to simple linear regression. Following the approach of the earlier study, where intermodel spread is used to assess the distribution of trends, but using the fixed-intercept trend metric demonstrates that recently observed trends in global mean temperature are consistent with the CMIP5 ensemble for all 15-yr intervals of observation?model divergence since 1970. Significant clustering of global trends according to modeling center indicates that the spread in CMIP5 trends is better characterized using ensemble members drawn across models as opposed to using ensemble members from a single model. Despite model?observation consistency at the global level, substantial regional discrepancies in surface temperature trends remain.
SN – 0894-8755
UR – https://doi.org/10.1175/JCLI-D-16-0123.1
Y2 – 2018/02/12
ER –

NR – 113
TY – JOUR
T1 – Role of Changes in Mean Temperatures versus Temperature Gradients in the Recent Widening of the Hadley Circulation
AU – Adam, Ori
AU – Schneider, Tapio
AU – Harnik, Nili
Y1 – 2014/07/28
PY – 2014
DA – 2014/10/01
DO – 10.1175/JCLI-D-14-00140.1
JF – Journal of Climate
JO – J. Climate
SP – 7450
EP – 7461
VL – 27
IS – 19
PB – American Meteorological Society
AB – AbstractThe Hadley circulation (HC) has widened in recent decades, and it widens as the climate warms in simulations. But the mechanisms responsible for the widening remain unclear, and the widening in simulations is generally smaller than observed.To identify mechanisms responsible for the HC widening and for model?observation discrepancies, this study analyzes how interannual variations of tropical-mean temperatures and meridional temperature gradients influence the HC width. Changes in mean temperatures are part of any global warming signal, whereas changes in temperature gradients are primarily associated with ENSO. Within this study, 6 reanalysis datasets, 22 Atmospheric Modeling Intercomparison Project (AMIP) simulations, and 11 historical simulations from phase 5 of the Climate Modeling Intercomparison Project (CMIP5) are analyzed, covering the years 1979?2012. It is found that the HC widens as mean temperatures increase or as temperature gradients weaken in most reanalyses and climate models. On average, climate models exhibit a smaller sensitivity of HC width to changes in mean temperatures and temperature gradients than do reanalyses. However, the sensitivities differ substantially among reanalyses, rendering the HC response to mean temperatures in climate models not statistically different from that in reanalyses.While global-mean temperatures did not increase substantially between 1997 and 2012, the HC continued to widen in most reanalyses. The analysis here suggests that the HC widening from 1979 to 1997 is primarily the result of global warming, whereas the widening of the HC from 1997 to 2012 is associated with increased midlatitude temperatures and hence reduced temperature gradients during this period.
SN – 0894-8755
UR – https://doi.org/10.1175/JCLI-D-14-00140.1
Y2 – 2018/02/12
ER –

NR – 114
TY – JOUR
AU – Wei, Meng
AU – Qiao, FangLi
PY – 2017
DA – 2017/02/01
TI – Attribution analysis for the failure of CMIP5 climate models to simulate the recent global warming hiatus
JO – Science China Earth Sciences
SP – 397
EP – 408
VL – 60
IS – 2
AB – The Coupled Model Inter-comparison Project Phase 5 (CMIP5) contains a group of state-of-the-art climate models and represents the highest level of climate simulation thus far. However, these models significantly overestimated global mean surface temperature (GMST) during 2006–2014. Based on the ensemble empirical mode decomposition (EEMD) method, the long term change of the observed GMST time series of HadCRUT4 records during 1850–2014 was analyzed, then the simulated GMST by 33 CMIP5 climate models was assessed. The possible reason that climate models failed to project the recent global warming hiatus was revealed. Results show that during 1850–2014 the GMST on a centennial timescale rose with fluctuation, dominated by the secular trend and the multi-decadal variability (MDV). The secular trend was relatively steady beginning in the early 20th century, with an average warming rate of 0.0883°C/decade over the last 50 years. While the MDV (with a ~65-year cycle) showed 2.5 multi-decadal waves during 1850–2014, which deepened and steepened with time, the alarming warming over the last quarter of the 20th century was a result of the concurrence of the secular warming trend and the warming phase of the MDV, both of which accounted one third of the temperature increase during 1975–1998. Recently the slowdown of global warming emerged as the MDV approached its third peak, leading to a reduction in the warming rate. A comparative analysis between the GMST time series derived from HadCRUT4 records and 33 CMIP5 model outputs reveals that the GMSTs during the historical simulation period of 1850–2005 can be reproduced well by models, especially on the accelerated global warming over the last quarter of 20th century. However, the projected GMSTs and their linear trends during 2006–2014 under the RCP4.5 scenario were significantly higher than observed. This is because the CMIP5 models confused the MDV with secular trend underlying the GMST time series, which results in a fast secular trend and an improper MDV with irregular phases and small amplitudes. This implies that the role of atmospheric CO2 in global warming may be overestimated, while the MDV which is an interior oscillation of the climate system may be underestimated, which should be related to insufficient understanding of key climatic internal dynamic processes. Our study puts forward an important criterion for the new generation of climate models: they should be able to simulate both the secular trend and the MDV of GMST.
SN – 1869-1897
UR – https://doi.org/10.1007/s11430-015-5465-y
DO – 10.1007/s11430-015-5465-y
ID – Wei2017
ER –

NR – 115
TY – JOUR
DB – PMC
AU – Zhou, Chunlüe
AU – Wang, Kaicun
T1 – Coldest Temperature Extreme Monotonically Increased and Hottest Extreme Oscillated over Northern Hemisphere Land during Last 114 Years
SN – 2045-2322
Y1 – 2016
PY – 2016/05/13
PY – 2015/10/22/received
PY – 2016/04/21/accepted
AB – Most studies on global warming rely on global mean surface temperature, whose change is jointly determined by anthropogenic greenhouse gases (GHGs) and natural variability. This introduces a heated debate on whether there is a recent warming hiatus and what caused the hiatus. Here, we presented a novel method and applied it to a 5°?×?5° grid of Northern Hemisphere land for the period 1900 to 2013. Our results show that the coldest 5% of minimum temperature anomalies (the coldest deviation) have increased monotonically by 0.22?°C/decade, which reflects well the elevated anthropogenic GHG effect. The warmest 5% of maximum temperature anomalies (the warmest deviation), however, display a significant oscillation following the Atlantic Multidecadal Oscillation (AMO), with a warming rate of 0.07?°C/decade from 1900 to 2013. The warmest (0.34?°C/decade) and coldest deviations (0.25?°C/decade) increased at much higher rates over the most recent decade than last century mean values, indicating the hiatus should not be interpreted as a general slowing of climate change. The significant oscillation of the warmest deviation provides an extension of previous study reporting no pause in the hottest temperature extremes since 1979, and first uncovers its increase from 1900 to 1939 and decrease from 1940 to 1969.
SP – 25721
VL – 6
DO – 10.1038/srep25721
AN – PMC4865736
UR – http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4865736/
U1 – 27172861[pmid]
J1 – Sci Rep
JF – Scientific Reports
PB – Nature Publishing Group
ER –

NR – 116
TY – JOUR
AU – Dai, Aiguo
AU – Fyfe, John C.
AU – Xie, Shang-Ping
AU – Dai, Xingang
TI – Decadal modulation of global surface temperature by internal climate variability
JA – Nature Climate Change
PY – 2015/04/13/online
VL – 5
SP – 555
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate2605
DO – 10.1038/nclimate2605
M3 –
L3 – https://www.nature.com/articles/nclimate2605#supplementary-information
AB – Despite a steady increase in atmospheric greenhouse gases (GHGs), global-mean surface temperature (T) has shown no discernible warming since about 2000, in sharp contrast to model simulations, which on average project strong warming1,2,3. The recent slowdown in observed surface warming has been attributed to decadal cooling in the tropical Pacific1,4,5, intensifying trade winds5, changes in El Niño activity6,7, increasing volcanic activity8,9,10 and decreasing solar irradiance7. Earlier periods of arrested warming have been observed but received much less attention than the recent period, and their causes are poorly understood. Here we analyse observed and model-simulated global T fields to quantify the contributions of internal climate variability (ICV) to decadal changes in global-mean T since 1920. We show that the Interdecadal Pacific Oscillation (IPO) has been associated with large T anomalies over both ocean and land. Combined with another leading mode of ICV, the IPO explains most of the difference between observed and model-simulated rates of decadal change in global-mean T since 1920, and particularly over the so-called ‘hiatus’ period since about 2000. We conclude that ICV, mainly through the IPO, was largely responsible for the recent slowdown, as well as for earlier slowdowns and accelerations in global-mean T since 1920, with preferred spatial patterns different from those associated with GHG-induced warming or aerosol-induced cooling. Recent history suggests that the IPO could reverse course and lead to accelerated global warming in the coming decades.
ER –

NR – 117
TY – JOUR
AU – Lin, Yong
AU – Franzke, Christian L. E.
TI – Scale-dependency of the global mean surface temperature trend and its implication for the recent hiatus of global warming
JA – Scientific Reports
PY – 2015/08/11/online
VL – 5
SP – 12971
EP –
PB – The Author(s)
SN –
UR – http://dx.doi.org/10.1038/srep12971
DO – 10.1038/srep12971
M3 – Article
L3 –
AB – Studies of the global mean surface temperature trend are typically conducted at a single (usually annual or decadal) time scale. The used scale does not necessarily correspond to the intrinsic scales of the natural temperature variability. This scale mismatch complicates the separation of externally forced temperature trends from natural temperature fluctuations. The hiatus of global warming since 1999 has been claimed to show that human activities play only a minor role in global warming. Most likely this claim is wrong due to the inadequate consideration of the scale-dependency in the global surface temperature (GST) evolution. Here we show that the variability and trend of the global mean surface temperature anomalies (GSTA) from January 1850 to December 2013, which incorporate both land and sea surface data, is scale-dependent and that the recent hiatus of global warming is mainly related to natural long-term oscillations. These results provide a possible explanation of the recent hiatus of global warming and suggest that the hiatus is only temporary.
ER –

NR – 118
TY – JOUR
T1 – Does the NMME Capture a Recent Decadal Shift toward Increasing Drought Occurrence in the Southwestern United States?
AU – Barnston, Anthony G.
AU – Lyon, Bradfield
Y1 – 2015/11/06
PY – 2015
DA – 2016/01/01
DO – 10.1175/JCLI-D-15-0311.1
JF – Journal of Climate
JO – J. Climate
SP – 561
EP – 581
VL – 29
IS – 2
PB – American Meteorological Society
AB – AbstractA global-scale decadal climate shift, beginning in 1998/99 and enduring through 2013, has been documented in recent studies, with associated precipitation shifts in key regions throughout the world. These precipitation shifts are most easily detected during March?May when ENSO effects are weak. Analyses have linked this climate shift to a shift in the Pacific decadal variability (PDV) pattern to its negative phase. Here the authors evaluate the predictive skill of the North American Multimodel Ensemble (NMME), and the CFSv2 model alone, in maintaining the observed precipitation shifts in seasonal forecasts, emphasizing the southwestern United States where deficient precipitation has tended to prevail since the late 1990s.The NMME hindcasts out to 6 months lead are found to maintain the observed decadal precipitation shifts in key locations qualitatively correctly, but with increasingly underestimated amplitude with increasing lead time. This finding holds in the separate CFSv2 model hindcasts. The decadal precipitation shift is relatively well reproduced in the southwestern United States. The general underestimation of the precipitation shift is suggested to be related to a muted reproduction of the observed shift in Pacific sea surface temperature (SST). This conclusion is supported by runs from a different (but overlapping) set of atmospheric models, which when forced with observed SST reproduce the decadal shifts quite well. Overall, the capability of the NMME model hindcasts to reflect the observed decadal rainfall pattern shift, but with weakened amplitude (especially at longer leads), underscores the broader challenge of retaining decadal signals in predictions of droughts and pluvials at seasonal-to-interannual time scales.
SN – 0894-8755
UR – https://doi.org/10.1175/JCLI-D-15-0311.1
Y2 – 2018/02/14
ER –

NR – 119
TY – JOUR
AU – Knutson, Thomas R.
AU – Ploshay, Jeffrey J.
PY – 2016
DA – 2016/09/01
TI – Detection of anthropogenic influence on a summertime heat stress index
JO – Climatic Change
SP – 25
EP – 39
VL – 138
IS – 1
AB – One of the most consequential impacts of anthropogenic warming on humans may be increased heat stress, combining temperature and humidity effects. Here we examine whether there are now detectable changes in summertime heat stress over land regions. As a heat stress metric we use a simplified wet bulb globe temperature (WBGT) index. Observed trends in WBGT (1973–2012) are compared to trends from CMIP5 historical simulations (eight-model ensemble) using either anthropogenic and natural forcing agents combined or natural forcings alone. Our analysis suggests that there has been a detectable anthropogenic increase in mean summertime heat stress since 1973, both globally and in most land regions analyzed. A detectable increase is found over a larger fraction of land for WBGT than for temperature, as WBGT summertime means have lower interannual variability than surface temperature at gridbox scales. Notably, summertime WBGT over land has continued increasing in recent years–consistent with climate models–despite the apparent ‘hiatus’ in global warming and despite a decreasing tendency in observed relative humidity over land since the late 1990s.
SN – 1573-1480
UR – https://doi.org/10.1007/s10584-016-1708-z
DO – 10.1007/s10584-016-1708-z
ID – Knutson2016
ER –

NR – 120
TY – JOUR
AU – Dong, Lu
AU – Zhou, Tianjun
AU – Dai, Aiguo
AU – Song, Fengfei
AU – Wu, Bo
AU – Chen, Xiaolong
TI – The Footprint of the Inter-decadal Pacific Oscillation in Indian Ocean Sea Surface Temperatures
JO – Scientific Reports
PY – 2016/02/17/online
VL – 6
SP – 21251
EP –
PB – The Author(s)
SN –
UR – http://dx.doi.org/10.1038/srep21251
DO – 10.1038/srep21251
M3 – Article
L3 – https://www.nature.com/articles/srep21251#supplementary-information
AB – Superimposed on a pronounced warming trend, the Indian Ocean (IO) sea surface temperatures (SSTs) also show considerable decadal variations that can cause regional climate oscillations around the IO. However, the mechanisms of the IO decadal variability remain unclear. Here we perform numerical experiments using a state-of-the-art, fully coupled climate model in which the external forcings with or without the observed SSTs in the tropical eastern Pacific Ocean (TEP) are applied for 1871–2012. Both the observed timing and magnitude of the IO decadal variations are well reproduced in those experiments with the TEP SSTs prescribed to observations. Although the external forcings account for most of the warming trend, the decadal variability in IO SSTs is dominated by internal variability that is induced by the TEP SSTs, especially the Inter-decadal Pacific Oscillation (IPO). The IPO weakens (enhances) the warming of the external forcings by about 50% over the IO during IPO’s cold (warm) phase, which contributes about 10% to the recent global warming hiatus since 1999. The decadal variability in IO SSTs is modulated by the IPO-induced atmospheric adjustment through changing surface heat fluxes, sea surface height and thermocline depth.
ER –

NR – 121
TY – JOUR
AU – Blanchette, Jeanne
AU – Huang, Yi
TI – Earth Infrared Radiation Spectra During Global Warming Hiatus
JO – McGill Science Undergraduate Research Journal
PY – 2015
VL – 10
IS – 1
SP – 14
EP – 17
UR – http://msurj.mcgill.ca/vol10/iss1/MSURJ2015.pdf#page=14
AB – Background: Since 1997-98, observations of annual mean surface temperature have shown a slowdown of global temperature increases, suggesting a hiatus in global warming. Given this finding, we are interested in diagnosing trends in the Earth’s outgoing longwave radiation (OLR) spectrum throughout the last decade. Methods: We calculated the trend in OLR measured by the Atmospheric Infrared Sounder (AIRS) aboard NASA’s Aqua satellite between 2003 and 2013, and compared these results with the trend in atmospheric and surface temperature and tropospheric absolute humidity, obtained from AIRS retrieval product and from the ECMWF (European Center for Medium range Weather Forecasting) Re-Analysis (ERA) interim product. We also isolated the greenhouse effect from the OLR trend by subtracting the amount of surface radiation emitted from the total radiation received by the sounder. Results: The OLR trend is negative in the CO2 absorption band, negative in the window spectral region, and positive in the water vapor band. The trend in surface and tropospheric temperature is negative, as is the trend in tropospheric absolute humidity. The greenhouse effect is increasing in the CO2 band, generally slightly increasing in the window region, and decreasing in the H2O band. Conclusion: Our results show that the CO2 forcing was still present globally through the last decade, with steadily increasing effects. Contributors to the negative trend in OLR in the window region are a small decrease in surface temperature and a strong decrease in tropospheric temperature, where tropospheric H2O emit radiation to space. The decreasing effect of water vapor in the H2O band is due to decreasing tropospheric humidity. This analysis will allow us to detect the changes in greenhouse gas forcing, to examine the correlated surface temperature response, and to study changes and effects in tropospheric water vapor concentration.
ER –

NR – 122
TY – JOUR
AU – Zhou, Chunlüe
AU – Wang, Kaicun
TI – Spatiotemporal Divergence of the Warming Hiatus over Land Based on Different Definitions of Mean Temperature
JO – Scientific Reports
PY – 2016/08/17/online
VL – 6
SP – 31789
PB – The Author(s)
UR – http://dx.doi.org/10.1038/srep31789
DO – 10.1038/srep31789
M3 – Article
AB – Existing studies of the recent warming hiatus over land are primarily based on the average of daily minimum and maximum temperatures (T2). This study compared regional warming rates of mean temperature based on T2 and T24 calculated from hourly observations available from 1998 to 2013. Both T2 and T24 show that the warming hiatus over land is apparent in the mid-latitudes of North America and Eurasia, especially in cold seasons, which is closely associated with the negative North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) and cold air propagation by the Arctic-original northerly wind anomaly into mid-latitudes. However, the warming rates of T2 and T24 are significantly different at regional and seasonal scales because T2 only samples air temperature twice daily and cannot accurately reflect land-atmosphere and incoming radiation variations in the temperature diurnal cycle. The trend has a standard deviation of 0.43?°C/decade for T2 and 0.41?°C/decade for T24, and 0.38?°C/decade for their trend difference in 5°?×?5° grids. The use of T2 amplifies the regional contrasts of the warming rate, i.e., the trend underestimation in the US and overestimation at high latitudes by T2.
ER –

NR – 123
TY – JOUR
AU – Urabe, Yusuke
AU – Maeda, Shuhei
TI – The Relationship between Japans Recent Temperature and Decadal Variability
T2 – SOLA
SN – 1349-6476
PB – Meteorological Society of Japan
PY – 2014
DA – 2014
VL – 10
SP – 176-179
UR – https://ci.nii.ac.jp/naid/130004704543/en/
DO – 10.2151/sola.2014-037
AB – Since the late 1990s, surface temperature has been higher than (near or lower than) normal for summer/autumn (winter/spring) over Japan, indicating that the seasonal temperature contrast has become enhanced. In order to relate this to global-scale variability on decadal timescale, atmospheric re-analysis and ocean assimilation datasets were analyzed. It is suggested that the La Niña-like conditions which have been frequently observed in the tropical Pacific oceanic and atmospheric fields in the last decade have contributed to these temperature tendencies observed in Japan. These global characteristics are consistent with the global warming hiatus. The results presented here indicate that not only interannual variability and century-scale long-term trends but also decadal variability in global oceanic and atmospheric fields significantly affect Japans temperature.
ER –

NR – 124
TY – JOUR
AU – He, Haozhe
AU – Yang, Jing
AU – Wu, Liguang
AU – Gong, Daoyi
AU – Wang, Bin
AU – Gao, Miaoni
PY – 2017
DA – 2017/03/01
TI – Unusual growth in intense typhoon occurrences over the Philippine Sea in September after the mid-2000s
JO – Climate Dynamics
SP – 1893
EP – 1910
VL – 48
IS – 5
AB – During the global warming hiatus period (1998–present), a pronounced increase in the number of intense typhoon occurrences was identified over the Philippine Sea (PS: 5°–25°N, 125°–140°E) in September after the mid-2000s. Comparing two periods before and after the mid-2000s indicates that intense typhoons rarely occurred over the PS in September before the mid-2000s, with a frequency of fewer than 0.4 per year, but reached up to nearly 1.5 per year after the mid-2000s. The abrupt increase in intense typhoon occurrences over the PS was primarily attributed to increased tropical cyclone (TC) genesis and favorable large-scale conditions for TC intensification. The increase in TC genesis number over the PS was caused by contributory dynamical conditions, including positive low-level relative vorticity anomalies and anomalous ascents, which corresponded to a southwestward shift and strengthening of the monsoon trough. In addition, among the favorable large-scale conditions, the increased relative humidity that resulted from intensified moisture flux convergence exerted essential effect on the TC intensification. These changes in atmospheric environmental conditions favoring intense typhoon occurrences over the PS were primarily associated with the change in the tropical Indo-Pacific sea surface temperature (SST) around the mid-2000s. Besides that, the positive feedback TCs exerted on the circulation was also conducive to the unusual growth in intense typhoon occurrences over the PS. And note that the role of SST anomalies in the air–sea interaction is the key to interpret why the unique phenomenon only occurred in September.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-016-3181-9
DO – 10.1007/s00382-016-3181-9
ID – He2017
ER –

NR – 125
TY – JOUR
AU – Lovejoy, S.
C8 – 2015GL065665
TI – Using scaling for macroweather forecasting including the pause
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 42
IS – 17
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2015GL065665
DO – 10.1002/2015GL065665
SP – 7148
EP – 7155
KW – forecast
KW – climate
KW – stochastic
KW – 1620 Climate dynamics
KW – 1616 Climate variability
KW – 1626 Global climate models
KW – 4435 Emergent phenomena
PY – 2015
AB – The ScaLIng Macroweather model (SLIMM) is a new class of stochastic atmospheric model. It exploits the large system memory to overcome the biases of conventional numerical climate models, it makes hindcasts and forecasts over macroweather forecast horizons (˜10?days to decades). Using the simplest (scalar), SLIMM model with only two parameters, we present various twentieth century hindcasts including several of the slowdown (“pause”) in the warming since 1998. The 1999–2013 hindcast is accurate to within ±0.11?K, with all the 2002–2013 anomalies hindcast to within ±0.02?K. In comparison, the Climate Model Intercomparison Project Phase 3 hindcasts were on average about 0.2?K too warm.
ER –

NR – 126
TY – JOUR
AU – Guan, Xiaodan
AU – Huang, Jianping
AU – Guo, Ruixia
AU – Lin, Pu
TI – The role of dynamically induced variability in the recent warming trend slowdown over the Northern Hemisphere
JO – Scientific Reports
PY – 2015/07/30/online
VL – 5
SP – 12669
PB – The Author(s)
UR – http://dx.doi.org/10.1038/srep12669
DO – 10.1038/srep12669
M3 – Article
AB – Since the slowing of the trend of increasing surface air temperature (SAT) in the late 1990?s, intense interest and debate have arisen concerning the contribution of human activities to the warming observed in previous decades. Although several explanations have been proposed for the warming-trend slowdown (WTS), none has been generally accepted. We investigate the WTS using a recently developed methodology that can successfully identify and separate the dynamically induced and radiatively forced SAT changes from raw SAT data. The dynamically induced SAT changes exhibited an obvious cooling effect relative to the warming effect of the adjusted SAT in the hiatus process. A correlation analysis suggests that the changes are dominated primarily by the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO). Our results confirm that dynamically induced variability caused the WTS. The radiatively forced SAT changes are determined mainly by anthropogenic forcing, indicating the warming influence of greenhouse gases (GHGs), which reached levels of 400?ppm during the hiatus period. Therefore, the global SAT will not remain permanently neutral. The increased radiatively forced SAT will be amplified by increased dynamically induced SAT when the natural mode returns to a warming phase in the next period.
ER –

NR – 127
TY – JOUR
AU – Pasini, Antonello
AU – Triacca, Umberto
AU – Attanasio, Alessandro
PY – 2017
DA – 2017/08/01
TI – Evidence for the role of the Atlantic multidecadal oscillation and the ocean heat uptake in hiatus prediction
JO – Theoretical and Applied Climatology
SP – 873
EP – 880
VL – 129
IS – 3
AB – The recent hiatus in global temperature at the surface has been analysed by several studies, mainly using global climate models. The common accepted picture is that since the late 1990s, the increase in anthropogenic radiative forcings has been counterbalanced by other factors, e.g., a decrease in natural forcings, augmented ocean heat storage and negative phases of ocean–atmosphere-coupled oscillation patterns. Here, simple vector autoregressive models are used for forecasting the temperature hiatus in the period 2001–2014. This gives new insight into the problem of understanding the ocean contribution (in terms of heat uptake and atmosphere–ocean-coupled oscillations) to the appearance of this recent hiatus. In particular, considering data about the ocean heat content until a depth of 700 m and the Atlantic multidecadal oscillation is necessary for correctly forecasting the hiatus, so catching both trend and interannual variability. Our models also show that the ocean heat uptake is substantially driven by the natural component of the total radiative forcing at a decadal time scale, confining the importance of the anthropogenic influences to a longer range warming of the ocean.
SN – 1434-4483
UR – https://doi.org/10.1007/s00704-016-1818-6
DO – 10.1007/s00704-016-1818-6
ID – Pasini2017
ER –

NR – 128
TY – JOUR
T1 – Extreme North America Winter Storm Season of 2013/14: Roles of Radiative Forcing and the Global Warming Hiatus
AU – Yang, Xiaosong
AU – Vecchi, G. A.
AU – Delworth, T. L.
AU – Paffendorf, K.
AU – Jia, L.
AU – Gudgel, R.
AU – Zeng, F.
AU – Underwood, Seth D.
Y1 – 2015/12/01
PY – 2015
DA – 2015/12/01
N1 – doi: 10.1175/BAMS-D-15-00133.1
DO – 10.1175/BAMS-D-15-00133.1
T2 – Bulletin of the American Meteorological Society
JF – Bulletin of the American Meteorological Society
JO – Bull. Amer. Meteor. Soc.
SP – S25
EP – S28
VL – 96
IS – 12
PB – American Meteorological Society
SN – 0003-0007
M3 – doi: 10.1175/BAMS-D-15-00133.1
UR – https://doi.org/10.1175/BAMS-D-15-00133.1
Y2 – 2018/02/14
AB – The extreme 2013/14 winter storm season over much of North America was made more likely by the multiyear anomalous tropical Pacific winds associated with the recent global warming hiatus.
ER –

NR – 129
TY – JOUR
AU – Huang, Rui Xin
PY – 2015
DA – 2015/12/01
TI – Heaving modes in the world oceans
JO – Climate Dynamics
SP – 3563
EP – 3591
VL – 45
IS – 11
AB – Part of climate changes on decadal time scales can be interpreted as the result of adiabatic motions associated with the adjustment of wind-driven circulation, i.e., the heaving of the isopycnal surfaces. Heat content changes in the ocean, including hiatus of global surface temperature and other phenomena, can be interpreted in terms of heaving associated with adjustment of wind-driven circulation induced by decadal variability of wind. A simple reduced gravity model is used to examine the consequence of adiabatic adjustment of the wind-driven circulation. Decadal changes in wind stress forcing can induce three-dimensional redistribution of warm water in the upper ocean. In particular, wind stress change can generate baroclinic modes of heat content anomaly in the vertical direction; in fact, changes in stratification observed in the ocean may be induced by wind stress change at local or in the remote parts of the world oceans. Intensification of the equatorial easterly can induce cooling in the upper layer and warming in the subsurface layer. The combination of this kind of heat content anomaly with the general trend of warming of the whole water column under the increasing greenhouse effect may offer an explanation for the hiatus of global surface temperature and the accelerating subsurface warming over the past 10–15 years. Furthermore, the meridional transport of warm water in the upper ocean can lead to sizeable transient meridional overturning circulation, poleward heat flux and vertical heat flux. Thus, heaving plays a key role in the oceanic circulation and climate.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-015-2557-6
DO – 10.1007/s00382-015-2557-6
ID – Huang2015
ER –

NR – 130
TY – JOUR
AU – Zhou, Chen
AU – Zelinka, Mark D.
AU – Klein, Stephen A.
TI – Impact of decadal cloud variations on the Earth’s energy budget
JO – Nature Geoscience
PY – 2016/10/31/online
VL – 9
SP – 871
PB – Nature Publishing Group
UR – http://dx.doi.org/10.1038/ngeo2828
DO – 10.1038/ngeo2828
L3 – https://www.nature.com/articles/ngeo2828#supplementary-information
AB – Feedbacks of clouds on climate change strongly influence the magnitude of global warming1,2,3. Cloud feedbacks, in turn, depend on the spatial patterns of surface warming4,5,6,7,8,9, which vary on decadal timescales. Therefore, the magnitude of the decadal cloud feedback could deviate from the long-term cloud feedback4. Here we present climate model simulations to show that the global mean cloud feedback in response to decadal temperature fluctuations varies dramatically due to time variations in the spatial pattern of sea surface temperature. We find that cloud anomalies associated with these patterns significantly modify the Earth’s energy budget. Specifically, the decadal cloud feedback between the 1980s and 2000s is substantially more negative than the long-term cloud feedback. This is a result of cooling in tropical regions where air descends, relative to warming in tropical ascent regions, which strengthens low-level atmospheric stability. Under these conditions, low-level cloud cover and its reflection of solar radiation increase, despite an increase in global mean surface temperature. These results suggest that sea surface temperature pattern-induced low cloud anomalies could have contributed to the period of reduced warming between 1998 and 2013, and offer a physical explanation of why climate sensitivities estimated from recently observed trends are probably biased low4.
ER –

NR – 131
TY – JOUR
AU – Wang, Linying
AU – Yuan, Xing
AU – Xie, Zhenghui
AU – Wu, Peili
AU – Li, Yaohui
TI – Increasing flash droughts over China during the recent global warming hiatus
JO – Scientific Reports
PY – 2016/08/11/online
VL – 6
SP – 30571
PB – The Author(s)
UR – http://dx.doi.org/10.1038/srep30571
DO – 10.1038/srep30571
L3 – https://www.nature.com/articles/srep30571#supplementary-information
AB – The recent global warming slowdown or hiatus after the big El Niño event in 1997/98 raises the questions of whether terrestrial hydrological cycle is being decelerated and how do the hydrological extremes respond to the hiatus. However, the rapidly developing drought events that are termed as “flash droughts” accompanied by extreme heat, low soil moisture and high evapotranspiration (ET), occurred frequently around the world, and caused devastating impacts on crop yields and water supply. Here, we investigate the long-term trend and variability of flash droughts over China. Flash droughts are most likely to occur over humid and semi-humid regions, such as southern and northeastern China. Flash drought averaged over China increased by 109% from 1979 to 2010, and the increase was mainly due to a long term warming of temperature (50%), followed by the contributions from decreasing soil moisture and increasing ET. There was a slight drop in temperature after 1997, but the increasing trend of flash droughts was tripled. Further results indicate that the decreasing temperature was compensated by the accelerated drying trends of soil moisture and enhanced ET, leading to an acceleration of flash droughts during the warming hiatus. The anthropogenic warming in the next few decades may exacerbate future flash drought conditions in China.
ER –

NR – 132
TY – JOUR
TI – Investigation on the Tendencies of the Land–Ocean Warming Contrast in the Recent Decades
T2 – IEEE Geoscience and Remote Sensing Letters
SP – 1522
EP – 1526
AU – L. Zhao
AU – J. Xu
AU – A. Powell
AU – D. Guo
AU – C. Shi
AU – M. Shao
AU – D. Wang
PY – 2016
KW – atmospheric temperature
KW – climatology
KW – ocean temperature
KW – troposphere
KW – AD 1980 01 to 2014 12
KW – land trend
KW – land-ocean warming contrast
KW – lower troposphere
KW – ocean surface warming trend
KW – ocean trend
KW – reconstructed data
KW – satellite microwave sounding unit retrieval
KW – surface climate temperature
KW – surface temperature observations
KW – Land surface
KW – Land surface temperature
KW – Market research
KW – Ocean temperature
KW – Sea surface
KW – Temperature distribution
KW – Global warming
KW – land–ocean warming contrast (LOWC)
KW – remote sensing
KW – temperature trend
DO – 10.1109/LGRS.2016.2594954
JO – IEEE Geoscience and Remote Sensing Letters
IS – 10
SN – 1545-598X
VO – 13
VL – 13
JA – IEEE Geoscience and Remote Sensing Letters
AB – In this letter, the surface climate temperature trends for the land and the oceans (land-ocean warming contrast) have been examined and compared based on five data sets. The five data sets included three reconstructed data sets of surface temperature observations and two data sets derived using the satellite microwave sounding unit retrieval products in the lower troposphere (LT) for the period from January 1980 to December 2014. Unlike previous studies, the current study shows that the warming trends significantly decreased over both the land and ocean since 1992 and reached their minimum (near zero) in the early 2000s, which is consistent with the occurrence of the warming hiatus. However, due to the sharp decrease in the surface warming trend over the land (1992 to 2007) in conjunction with an increase in the ocean surface warming trend after 2002, the combined trend carries an overall positive sign (between 2005 and 2007) due to the greater ocean warming trend. The rate of warming increase in the ocean, which began in 2002, is surprisingly fast and is approaching the highest warming trends observed over the land since 1980. These basic land and ocean trend results are confirmed by all five data sets with slightly different values due to the various techniques used in compiling the data sets. However, there is consistency in the overall trend pattern results.
ER –

NR – 133
TY – JOUR
AU – Santer, Benjamin D.
AU – Solomon, Susan
AU – Bonfils, Céline
AU – Zelinka, Mark D.
AU – Painter, Jeffrey F.
AU – Beltran, Francisco
AU – Fyfe, John C.
AU – Johannesson, Gardar
AU – Mears, Carl
AU – Ridley, David A.
AU – Vernier, Jean-Paul
AU – Wentz, Frank J.
C8 – 2014GL062366
TI – Observed multivariable signals of late 20th and early 21st century volcanic activity
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 42
IS – 2
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL062366
DO – 10.1002/2014GL062366
SP – 500
EP – 509
KW – Volcanic forcing
KW – Climate change
KW – Signal detection
KW – 0370 Volcanic effects
KW – 1616 Climate variability
KW – 1640 Remote sensing
KW – 3354 Precipitation
PY – 2015
AB – The relatively muted warming of the surface and lower troposphere since 1998 has attracted considerable attention. One contributory factor to this “warming hiatus” is an increase in volcanically induced cooling over the early 21st century. Here we identify the signals of late 20th and early 21st century volcanic activity in multiple observed climate variables. Volcanic signals are statistically discernible in spatial averages of tropical and near-global SST, tropospheric temperature, net clear-sky short-wave radiation, and atmospheric water vapor. Signals of late 20th and early 21st century volcanic eruptions are also detectable in near-global averages of rainfall. In tropical average rainfall, however, only a Pinatubo-caused drying signal is identifiable. Successful volcanic signal detection is critically dependent on removal of variability induced by the El Niño–Southern Oscillation.
ER –

NR – 134
TY – JOUR
AU – Peyser, Cheryl E.
AU – Yin, Jianjun
AU – Landerer, Felix W.
AU – Cole, Julia E.
C8 – 2016GL069401
TI – Pacific sea level rise patterns and global surface temperature variability
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 43
IS – 16
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2016GL069401
DO – 10.1002/2016GL069401
SP – 8662
EP – 8669
KW – sea level rise
KW – Pacific
KW – warming hiatus
KW – global temperature
KW – 1616 Climate variability
KW – 1641 Sea level change
PY – 2016
AB – During 1998–2012, climate change and sea level rise (SLR) exhibit two notable features: a slowdown of global surface warming (hiatus) and a rapid SLR in the tropical western Pacific. To quantify their relationship, we analyze the long-term control simulations of 38 climate models. We find a significant and robust correlation between the east-west contrast of dynamic sea level (DSL) in the Pacific and global mean surface temperature (GST) variability on both interannual and decadal time scales. Based on linear regression of the multimodel ensemble mean, the anomalously fast SLR in the western tropical Pacific observed during 1998–2012 indicates suppression of a potential global surface warming of 0.16°?±?0.06°C. In contrast, the Pacific contributed 0.29°?±?0.10°C to the significant interannual GST increase in 1997/1998. The Pacific DSL anomalies observed in 2015 suggest that the strong El Niño in 2015/2016 could lead to a 0.21°?±?0.07°C GST jump.
ER –

NR – 135
TY – JOUR
AU – Chikamoto, Y.
AU – Mochizuki, T.
AU – Timmermann, A.
AU – Kimoto, M.
AU – Watanabe, M.
C8 – 2016GL069544
TI – Potential tropical Atlantic impacts on Pacific decadal climate trends
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 43
IS – 13
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2016GL069544
DO – 10.1002/2016GL069544
SP – 7143
EP – 7151
KW – decadal climate variability
KW – global warming hiatus
KW – atmosphere-ocean interaction
KW – climate change
KW – data assimilation
KW – 1616 Climate variability
KW – 1620 Climate dynamics
KW – 3373 Tropical dynamics
KW – 4504 Air/sea interactions
PY – 2016
AB – The tropical Pacific cooling from the early 1990s to 2013 has contributed to the slowdown of globally averaged sea surface temperatures (SSTs). The origin of this regional cooling trend still remains elusive. Here we demonstrate that the remote impact of Atlantic SST anomalies, as well as local atmosphere-ocean interactions, contributed to the eastern Pacific cooling during this period. By assimilating observed three-dimensional Atlantic temperature and salinity anomalies into a coupled general circulation model, we are able to qualitatively reproduce the observed Pacific decadal trends of SST and sea level pressure (SLP), albeit with reduced amplitude. Although a major part of the Pacific SLP trend can be explained by equatorial Pacific SST forcing only, the origin of this low-frequency variability can be traced back further to the remote impacts of equatorial Atlantic and South Atlantic SST trends. Atlantic SST impacts on the atmospheric circulation can also be detected for the Northeastern Pacific, thus providing a linkage between Atlantic climate and Western North American drought conditions.
ER –

NR – 136
TY – JOUR
AU – Ramesh, Nandini
AU – Cane, Mark A.
AU – Seager, Richard
AU – Lee, Dong Eun
PY – 2017
DA – 2017/10/01
TI – Predictability and prediction of persistent cool states of the Tropical Pacific Ocean
JO – Climate Dynamics
SP – 2291
EP – 2307
VL – 49
IS – 7
AB – The Tropical Pacific Ocean displays persistently cool sea surface temperature (SST) anomalies that last several years to a decade, with either no El Niño events or a few weak El Niño events. These cause large-scale droughts in the extratropics, including major North American droughts such as the 1930s Dust Bowl, and also modulate the global mean surface temperature. Here we show that two models with different levels of complexity—the Zebiak–Cane intermediate model and the Geophysical Fluid Dynamics Laboratory Coupled Model version 2.1—are able to produce such periods in a realistic manner. We then test the predictability of these periods in the Zebiak–Cane model using an ensemble of experiments with perturbed initial states. Our results show that in most cases the cool mean state is predictable. We then apply this method to make retrospective forecasts of shifts in the decadal mean state and to forecast the mean state of the Tropical Pacific Ocean for the upcoming decade. Our results suggest that the Pacific will undergo a shift to a warmer mean state after the 2015–2016 El Niño. This could imply the cessation of the drier than normal conditions that have generally afflicted southwest North America since the 1997–1998 El Niño, as well as the twenty-first-century pause in global warming. Implications for our understanding of the origins of such persistent cool states and the possibility of improving predictions of large-scale droughts are discussed.
SN – 1432-0894
UR – https://doi.org/10.1007/s00382-016-3446-3
DO – 10.1007/s00382-016-3446-3
ID – Ramesh2017
ER –

NR – 137
TY – JOUR
AU – Knutson, Thomas R.
AU – Zhang, Rong
AU – Horowitz, Larry W.
TI – Prospects for a prolonged slowdown in global warming in the early 21st century
JO – Nature Communications
PY – 2016/11/30/online
VL – 7
SP – 13676
PB – The Author(s)
UR – http://dx.doi.org/10.1038/ncomms13676
DO – 10.1038/ncomms13676
L3 – https://www.nature.com/articles/ncomms13676#supplementary-information
AB – Global mean temperature over 1998 to 2015 increased at a slower rate (0.1?K decade-1) compared with the ensemble mean (forced) warming rate projected by Coupled Model Intercomparison Project 5 (CMIP5) models (0.2?K decade-1). Here we investigate the prospects for this slower rate to persist for a decade or more. The slower rate could persist if the transient climate response is overestimated by CMIP5 models by a factor of two, as suggested by recent low-end estimates. Alternatively, using CMIP5 models’ warming rate, the slower rate could still persist due to strong multidecadal internal variability cooling. Combining the CMIP5 ensemble warming rate with internal variability episodes from a single climate model—having the strongest multidecadal variability among CMIP5 models—we estimate that the warming slowdown (<0.1?K decade-1 trend beginning in 1998) could persist, due to internal variability cooling, through 2020, 2025 or 2030 with probabilities 16%, 11% and 6%, respectively.
ER –

NR – 138
TY – JOUR
AU – Gleisner, Hans
AU – Thejll, Peter
AU – Christiansen, Bo
AU – Nielsen, Johannes K.
C8 – 2014GL062596
TI – Recent global warming hiatus dominated by low-latitude temperature trends in surface and troposphere data
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 42
IS – 2
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL062596
DO – 10.1002/2014GL062596
SP – 510
EP – 517
KW – hiatus
KW – troposphere
KW – temperature trends
KW – 1620 Climate dynamics
KW – 1640 Remote sensing
KW – 3309 Climatology
PY – 2015
AB – Over the last 15 years, global mean surface temperatures exhibit only weak trends. Recent studies have attempted to attribute this so called temperature hiatus to several causes, amongst them incomplete sampling of the rapidly warming Arctic region. We here examine zonal mean temperature trends in satellite-based tropospheric data sets (based on data from (Advanced) Microwave Sounding Unit and Global Navigation Satellite System Radio Occultation instruments) and in global surface temperatures (HadCRUT4). Omission of successively larger polar regions from the global mean temperature calculations, in both tropospheric and surface data sets, shows that data gaps at high latitudes cannot explain the observed differences between the hiatus and the prehiatus period. Instead, the dominating causes of the global temperature hiatus are found at low latitudes. The combined use of several independent data sets, representing completely different measurement techniques and sampling characteristics, strengthens the conclusions.
ER –

NR – 139
TY – JOUR
AU – England, Matthew H.
AU – Kajtar, Jules B.
AU – Maher, Nicola
TI – Robust warming projections despite the recent hiatus
JO – Nature Climate Change
PY – 2015/04/23/online
VL – 5
SP – 394
PB – Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.
UR – http://dx.doi.org/10.1038/nclimate2575
DO – 10.1038/nclimate2575
L3 – https://www.nature.com/articles/nclimate2575#supplementary-information
AB – The hiatus in warming has led to questions about the reliability of long-term projections, yet here we show they are statistically unchanged when considering only ensemble members that capture the recent hiatus. This demonstrates the robust nature of twenty-first century warming projections.
ER –

NR – 140
TY – JOUR
T1 – Role of Indian Ocean SST variability on the recent global warming hiatus
AU – Arora, Anika
AU – Rao, Suryachandra A.
AU – Chattopadhyay, R.
AU – Goswami, Tanmoy
AU – George, Gibies
AU – Sabeerali, C.T.
JO – Global and Planetary Change
VL – 143
SP – 21
EP – 30
PY – 2016
DA – 2016/08/01/
SN – 0921-8181
DO – https://doi.org/10.1016/j.gloplacha.2016.05.009
UR – http://www.sciencedirect.com/science/article/pii/S0921818115300412
KW – Global warming
KW – Large-scale teleconnections
KW – Air-sea coupling
AB – Previous studies have shown a slowdown in the warming rate of the annual mean global surface temperature in the recent decade and it is referred to as the hiatus in global warming. Some recent studies have suggested that the hiatus in global warming is possibly due to strong cooling in the tropical Pacific. This study investigates the possible role of the Indian Ocean warming on the tropical Pacific cooling. Despite the continued rise in sea surface temperature (SST) over the tropical Indian Ocean, SST over the tropical Pacific has shown a cooling trend in the recent decade (2002 – 2012). It is well known fact that the Indian Ocean and the Pacific Ocean are strongly coupled to each other and the Indian Ocean basin wide warming is triggered by El Niño on interannual time scale. However, in the recent decade, this relationship is weakening. The recent Indian Ocean warming is triggering a Matsuno-Gill type response in the atmosphere by generating anomalous cyclonic circulations on either side of equator over the tropical Indian Ocean and anomalous easterlies along the tropical Pacific Ocean. These anomalous easterlies result in Ekman divergence in the equatorial Pacific and produce upwelling Kelvin waves, cools the tropical Pacific and therefore indirectly contributes to the hiatus in global warming.
ER –

NR – 141
TY – JOUR
T1 – A Significant Component of Unforced Multidecadal Variability in the Recent Acceleration of Global Warming
AU – DelSole, Timothy
AU – Tippett, Michael K.
AU – Shukla, Jagadish
Y1 – 2010/09/22
PY – 2010
DA – 2011/02/01
DO – 10.1175/2010JCLI3659.1
JF – Journal of Climate
JO – J. Climate
SP – 909
EP – 926
VL – 24
IS – 3
PB – American Meteorological Society
AB – Abstract The problem of separating variations due to natural and anthropogenic forcing from those due to unforced internal dynamics during the twentieth century is addressed using state-of-the-art climate simulations and observations. An unforced internal component that varies on multidecadal time scales is identified by a new statistical method that maximizes integral time scale. This component, called the internal multidecadal pattern (IMP), is stochastic and hence does not contribute to trends on long time scales; however, it can contribute significantly to short-term trends. Observational estimates indicate that the trend in the spatially averaged ?well observed? sea surface temperature (SST) due to the forced component has an approximately constant value of 0.1 K decade?1, while the IMP can contribute about ±0.08 K decade?1 for a 30-yr trend. The warming and cooling of the IMP matches that of the Atlantic multidecadal oscillation and is of sufficient amplitude to explain the acceleration in warming during 1977?2008 as compared to 1946?77, despite the forced component increasing at the same rate during these two periods. The amplitude and time scale of the IMP are such that its contribution to the trend dominates that of the forced component on time scales shorter than 16 yr, implying that the lack of warming trend during the past 10 yr is not statistically significant. Furthermore, since the IMP varies naturally on multidecadal time scales, it is potentially predictable on decadal time scales, providing a scientific rationale for decadal predictions. While the IMP can contribute significantly to trends for periods of 30 yr or shorter, it cannot account for the 0.8°C warming that has been observed in the twentieth-century spatially averaged SST.
SN – 0894-8755
UR – https://doi.org/10.1175/2010JCLI3659.1
Y2 – 2018/02/19
ER –

NR – 142
TY – JOUR
T1 – Changes in Aridity in Response to Warming Hiatus
AU – Guan, Xiaodan
AU – Huang, Jianping
AU – Guo, Ruixia
PY – 2016
JF – Journal of Meteorological Research
VL – 31
SP – 117
EP – 125
DO – 10.1007/s13351-017-6038-1
AB – The global warming trend slowdown or warming hiatus began around the year 2000 and has persisted for nearly 15 years. Most studies have focused on the interpretation underlying this temperature change. In this study, changes in the global aridity index (AI) were analyzed using a newly developed dynamical adjustment method that can successfully identify and separate dynamically induced and radiatively-forced aridity changes in the raw data. The AI and Palmer Drought Severity Index (PDSI) appeared a wetting zone over the mid-to-high latitudes of the Northern Hemisphere in recent decades. The dynamical adjustment analysis suggests that this wetting zone occurred in response to the global warming hiatus. The dynamically-induced AI (DAI) played a major role in the AI changes during the hiatus period, and its relationships with the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO) and Atlantic Multi-decadal Oscillation (AMO) also indicate that different phases of the NAO, PDO, and AMO contributed to different performance of the DAI over the Northern Hemisphere. Although the aridity wetting over the mid-to-high latitudes may relieve long-term drying in certain regions, the hiatus is temporary, and so is the relief. Accelerated global warming will return when the NAO, PDO, and AMO revert to their opposite phases in the future, and the wetting zone is likely to disappear.
ER –

NR – 143
TY – JOUR
AU – Tan, Ming
PY – 2016
DA – 2016/06/01
TI – Circulation background of climate patterns in the past millennium: Uncertainty analysis and re-reconstruction of ENSO-like state
JO – Science China Earth Sciences
SP – 1225
EP – 1241
VL – 59
IS – 6
AB – The question of whether or not global warming has paused since more than ten years ago, namely “warming hiatus”, has attracted the attention of climate science community including the IPCC. Some authors have attributed the “warming hiatus” to the internal changes in the climate system, i.e., the recombination of ocean-atmosphere circulations. Therefore, it is necessary to propose higher requirements on reconstructing circulation background of climate change for the past millennium. However, the analyses of changes in atmospheric circulation over the last millennium as well as the conclusions of related regional climate patterns are so widely different and contradictory, bringing uncertainties to our understanding of regional even global climate change to a great extent. On the other hand, in the last 10 years the high-precision U/Th-dated stalagmite oxygen isotope ratio (d18O) sequences provided an accurate chronological frame for the paleoclimate study of the middle and late Pleistocene, in which all authors from China took the Chinese stalagmite d18O as the summer monsoon index without exception. However, this point of view misleads the climate scientists into thinking that the stalagmite d18O can be as the proxy of precipitation amount. Nevertheless, it is well known that all of these records have a lot in common in the low frequency trend. However, most sequences cannot be calibrated by instrumental precipitation records, and thus the uncertainty of the climate research framework of China and even of the world has increased. Therefore, it is imperative for climatology to clarify the origin of contradiction and to reduce the uncertainty as early as possible. On the basis of analyzing the significance of stalagmite d18O in the monsoon regions of China, the author tries to propose a new circulation proxy in this paper: integrating the Chinese stalagmite oxygen isotope sequence to reconstruct the tropical Pacific sea surface temperature gradient, i.e., the large-scale ENSO-like state over the past millennium. Furthermore, the author speculates that it was warm in the modern times and the Medieval Period, but the circulation recombination was different in both periods. And this inference could be supported by the longer record since Last Glacial Maximum. In other words, the attribution analysis of the identical low-frequency trends of Chinese stalagmite d18O on a large scale shows that the ENSO-like state controls the climate change in the monsoon regions of China at different time scales (from interannual to century or even longer time scales). Wherein the important connection of circulations is the western Pacific subtropical high (WPSH), that is to say, besides the interannual and decadal time scales, the WPSH would possess the circulation mode on longer timescales. For example, we may discuss the change of the WPSH in the whole Holocene epoch, i.e., the half precession period. These discussions could make sense to the study of not only the paleoclimate but also the modern climate.
SN – 1869-1897
UR – https://doi.org/10.1007/s11430-015-5256-6
DO – 10.1007/s11430-015-5256-6
ID – Tan2016
ER –

NR – 144
TY – JOUR
DB – PMC
AU – Cheng, Lijing
AU – Zheng, Fei
AU – Zhu, Jiang
T1 – Distinctive ocean interior changes during the recent warming slowdown
SN – 2045-2322
Y1 – 2015
PY – 2015/09/23
PY – 2015/03/12/received
PY – 2015/08/26/accepted
AB – The earth system experiences continuous heat input, but a “climate hiatus” of upper ocean waters has been observed in this century. This leads to a question: where is the extra heat going? Using four in situ observation datasets, we explore the ocean subsurface temperature changes from 2004 to 2013. The observations all show that the ocean has continued to gain heat in this century, which is indicative of anthropogenic global warming. However, a distinctive pattern of change in the interior ocean is observed. The sea surface (1–100?m) temperature has decreased in this century, accompanied by warming in the 101–300?m layer. This pattern is due to the changes in the frequency of El Niño and La Niña events (ENSO characteristics), according to both observations and CMIP5 model simulations. In addition, we show for the first time that the ocean subsurface within 301–700?m experienced a net cooling, indicative of another instance of variability in the natural ocean. Furthermore, the ocean layer of 701–1500?m has experienced significant warming.
SP – 14346
VL – 5
DO – 10.1038/srep14346
AN – PMC4585812
UR – http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4585812/
U1 – 26394551[pmid]
J1 – Sci Rep
JF – Scientific Reports
PB – Nature Publishing Group
ER –

NR – 145
TY – JOUR
AU – Jochner, Susanne
AU – Menzel, Annette
TI – Does flower phenology mirror the slowdown of global warming?
JO – Ecology and Evolution
JA – Ecol Evol
VL – 5
IS – 11
SN – 2045-7758
UR – http://dx.doi.org/10.1002/ece3.1503
DO – 10.1002/ece3.1503
SP – 2284
EP – 2295
KW – Bayesian statistics
KW – climate change
KW – flowering
KW – multiple change-point model
KW – phenology
KW – trend
PY – 2015
AB – Although recent global warming trends in air temperature are not as pronounced as those observed only one decade ago, global mean temperature is still at a very high level. Does plant phenology – which is believed to be a suitable indicator of climate change – respond in a similar way, that is, does it still mirror recent temperature variations? We explored in detail long-term flowering onset dates of snowdrop, cherry, and lime tree and relevant spring temperatures at three sites in Germany (1901–2012) using the Bayesian multiple change-point approach. We investigated whether mean spring temperature changes were amplified or slowed down in the past decade and how plant phenology responded to the most recent temperature changes. Incorporating records with different end points (i.e., 2002 and 2012), we compared differences in trends and inferred possible differences caused by extrapolating phenological and meteorological data. The new multiple-change point approach is characterized by an enhanced structure and greater flexibility compared to the one change point model. However, the highest model probabilities for phenological (meteorological) records were still obtained for the one change point (linear) model. Marked warming trends in the recent decade were only revealed for mean temperatures of March to May, here better described with one or two change point models. In the majority of cases analyzed, changes in temperatures were well mirrored by phenological changes. However, temperatures in March to May were linked to less strongly advancing onset dates for lime tree flowering during the period 1901-2012, pointing to the likely influence of photoperiodic constraints or unfulfilled chilling requirements. Due to the slowdown of temperature increase, analyses conducted on records ending in 2002 demonstrated distinct differences when compared with records ending in 2012. Extrapolation of trends could therefore (along with the choice of the statistical method) lead to distinctly different results and most recent data should be integrated in order not to over- or underestimate future phenological changes.
ER –

NR – 146
TY – JOUR
AU – Dieng, Habib B.
AU – Palanisamy, Hindumathi
AU – Cazenave, Anny
AU – Meyssignac, Benoit
AU – von Schuckmann, Karina
PY – 2015
DA – 2015/03/01
TI – The Sea Level Budget Since 2003: Inference on the Deep Ocean Heat Content
JO – Surveys in Geophysics
SP – 209
EP – 229
VL – 36
IS – 2
AB – This study provides an overview of the various components of the global mean sea level evolution over two time spans: (1) 2005–2012 (corresponding to the full deployment of the Argo program) and (2) 2003–2012. Using a sea level budget approach, we compare altimetry-based global mean sea level, global ocean mass from GRACE space gravimetry and steric sea level from Argo and other in situ measurements. One goal of this study is to investigate whether it is possible to constrain the deep ocean contribution to the global mean sea level rise over the last decade. This question is particularly relevant, considering the current debate about the ‘hiatus,’ i.e., the observed recent pause of the global mean air and sea surface temperature evolution while the planet is still in thermal imbalance. We consider a total of 16 different data sets. Differences are noticed between data sets related to each variable (sea level, ocean mass and steric sea level), mostly due to data processing issues. Therefore, we perform the analysis using averages of the available data sets. For each period, we find that, when removing from the global mean sea level, the contributions of the global mean ocean mass and steric sea level (estimated for the 0–1,500 m ocean layer), there remains a residual signal displaying a positive slope of 0.3 ± 0.6 and 0.55 ± 0.6 mm/year over 2005–2012 and 2003–2012, respectively. Comparing with an ocean reanalysis and according to direct (but sparse) ocean temperature measurements below 1,500 m, it seems unlikely that the observed residual signal can be attributed to deep (below 1,500 m) ocean warming, in agreement with other recently published results. We estimate that it possibly reflects, at least partly, the signature of a missing upper ocean steric signal in regions uncovered by current observing systems. Our study also shows a steady warming increase since 2003 of the 700–1,500 m ocean layer (amounting ~0.2 mm/year in steric sea level equivalent), confirming previous findings, but seen in our study in each of the eight different steric data sets considered.
SN – 1573-0956
UR – https://doi.org/10.1007/s10712-015-9314-6
DO – 10.1007/s10712-015-9314-6
ID – Dieng2015
ER –

NR – 147
TY – JOUR
AU – Ying, Lingxiao
AU – Shen, Zehao
AU – Piao, Shilong
C8 – 2015GL064884
TI – The recent hiatus in global warming of the land surface: Scale-dependent breakpoint occurrences in space and time
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 42
IS – 15
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2015GL064884
DO – 10.1002/2015GL064884
SP – 6471
EP – 6478
KW – scale-dependent temperature trend change
KW – statistical method
KW – Asia midlatitude in winter
KW – 1620 Climate dynamics
PY – 2015
AB – The spatial and temporal variability of the recent land warming hiatus have seldom been explored, despite their importance for understanding the mechanisms underlying the phenomenon. In this study, we applied piecewise linear regression to investigate the spatiotemporal patterns of the breakpoint time of warming over 40?years (1974–2013). Our results showed that at the global scale, mean annual temperature (MAT) over the land increased significantly until 2005 and that the warming trend then stalled. However, the breakpoint time of the warming varied greatly among different seasons and continents. We found no statistically significant breakpoint in MAT over the Northern Hemisphere, but MAT over the Southern Hemisphere showed a significant breakpoint (P? 0.5), with root mean squared error 1500m. The Hilbert spectrum from the OHC in the Labrador Sea interior reveals two important components at frequencies of 0.8-1.2cycleyr-1 (T=0.8–1.25 years) and 0.1-0.3cycleyr-1 (T=3.3–10 years), respectively, superimposed on the warming trends. The former corresponds to the dominant seasonal cycle due to surface heating, while the latter is concomitant with the timing of the reoccurrence of convective events. We also found that the cumulative North Atlantic Oscillation (NAO) index significantly correlates to the low-frequency OHC variations. Therefore, the interannual signals in the Labrador Sea at especially the intermediate layers are attributed to changes in the deep convective processes and the atmospheric conditions. By comparing with an extended OHC record (1945–2010), it was further shown that the warming trends obtained from the 10-year Argo record are part of multi-decadal variations that presumably reflect the Atlantic Multi-decadal Oscillation (AMO). In addition, the recent OHC changes in the Labrador Sea (i.e., increased heat in the deeper layers) may be related to the current global warming hiatus, suggesting the potential contributions from the Atlantic Meridional Overturning Circulation (AMOC) to the low-frequency OHC in the Labrador Sea.
ER –

NR – 180
TY – JOUR
T1 – Very early warning of next El Niño
JF – Proceedings of the National Academy of Sciences
JO – Proc Natl Acad Sci USA
SP – 2064
LP – 2066
M3 – 10.1073/pnas.1323058111
VL – 111
IS – 6
AU – Ludescher, Josef
AU – Gozolchiani, Avi
AU – Bogachev, Mikhail I.
AU – Bunde, Armin
AU – Havlin, Shlomo
AU – Schellnhuber, Hans Joachim
Y1 – 2014/02/11
UR – http://www.pnas.org/content/111/6/2064.abstract
N2 – The most important driver of climate variability is the El Niño Southern Oscillation, which can trigger disasters in various parts of the globe. Despite its importance, conventional forecasting is still limited to 6 mo ahead. Recently, we developed an approach based on network analysis, which allows projection of an El Niño event about 1 y ahead. Here we show that our method correctly predicted the absence of El Niño events in 2012 and 2013 and now announce that our approach indicated (in September 2013 already) the return of El Niño in late 2014 with a 3-in-4 likelihood. We also discuss the relevance of the next El Niño to the question of global warming and the present hiatus in the global mean surface temperature.
ER –

NR – 181
TY – JOUR
AU – Laepple, T.
AU – Huybers, P.
TI – Global and regional variability in marine surface temperatures
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 7
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL059345
DO – 10.1002/2014GL059345
SP – 2528
EP – 2534
KW – climate variability
KW – marine temperature variability
KW – model-data comparison
KW – CMIP5
KW – HadSST3
KW – 1616 Climate variability
KW – 1635 Oceans
KW – 1626 Global climate models
KW – 4215 Climate and interannual variability
PY – 2014
AB – The temperature variability simulated by climate models is generally consistent with that observed in instrumental records at the scale of global averages, but further insight can also be obtained from regional analysis of the marine temperature record. A protocol is developed for comparing model simulations to observations that account for observational noise and missing data. General consistency between Coupled Model Intercomparison Project Phase 5 model simulations and regional sea surface temperature variability is demonstrated at interannual timescales. At interdecadal timescales, however, the variability diagnosed from observations is significantly greater. Discrepancies are greatest at low latitudes, with none of the 41 models showing equal or greater interdecadal variability. The pattern of suppressed variability at longer timescales and smaller spatial scales appears consistent with models generally being too diffusive. Suppressed variability of low-latitude marine temperatures points to underestimation of intrinsic variability and may help explain why few models reproduce the observed temperature trends during the last 15?years.
ER –

NR – 182
TY – JOUR
AU – de Boisséson, E.
AU – Balmaseda, M. A.
AU – Abdalla, S.
AU – Källén, E.
AU – Janssen, P. A. E. M.
TI – How robust is the recent strengthening of the Tropical Pacific trade winds?
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 41
IS – 12
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL060257
DO – 10.1002/2014GL060257
SP – 4398
EP – 4405
KW – Tropical Pacific
KW – wind variability
KW – 3305 Climate change and variability
KW – 3315 Data assimilation
KW – 3339 Ocean/atmosphere interactions
PY – 2014
AB – The persistent strengthening of the trade winds over the Pacific Ocean over the past 20 years has recently been proposed as a driver for the increase of ocean heat uptake linked to the hiatus in surface global warming. Crucial aspects in this argument are the reliability of the wind signal, usually derived from atmospheric reanalyses, and the ability of models to represent it. This study addresses these two aspects by comparing various observations with reanalyses and model integrations from the European Centre for Medium-Range Weather Forecasts system. We show that the strengthening of trades over the Pacific is a robust feature in several observational data sets as well as in the reanalyses based on full and limited sets of observations. The wind trend is also reproduced in an atmospheric model integration forced by sea surface temperature analysis, a result that opens the doors to further investigation on the nature of the changes.
ER –

NR – 183
TY – JOUR
AU – Gleckler, Peter J.
AU – Durack, Paul J.
AU – Stouffer, Ronald J.
AU – Johnson, Gregory C.
AU – Forest, Chris E.
TI – Industrial-era global ocean heat uptake doubles in recent decades
JA – Nature Climate Change
PY – 2016/01/18/online
VL – 6
SP – 394
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate2915
DO – 10.1038/nclimate2915
M3 –
L3 – https://www.nature.com/articles/nclimate2915#supplementary-information
AB – Formal detection and attribution studies have used observations and climate models to identify an anthropogenic warming signature in the upper (0–700?m) ocean1,2,3,4. Recently, as a result of the so-called surface warming hiatus, there has been considerable interest in global ocean heat content (OHC) changes in the deeper ocean, including natural and anthropogenically forced changes identified in observational5,6,7, modelling8,9 and data re-analysis10,11 studies. Here, we examine OHC changes in the context of the Earth’s global energy budget since early in the industrial era (circa 1865–2015) for a range of depths. We rely on OHC change estimates from a diverse collection of measurement systems including data from the nineteenth-century Challenger expedition12, a multi-decadal record of ship-based in situ mostly upper-ocean measurements, the more recent near-global Argo floats profiling to intermediate (2,000?m) depths13, and full-depth repeated transoceanic sections5. We show that the multi-model mean constructed from the current generation of historically forced climate models is consistent with the OHC changes from this diverse collection of observational systems. Our model-based analysis suggests that nearly half of the industrial-era increases in global OHC have occurred in recent decades, with over a third of the accumulated heat occurring below 700?m and steadily rising.
ER –

NR – 184
TY – JOUR
AU – Liu, Qin-Yan
AU – Feng, Ming
AU – Wang, Dongxiao
AU – Wijffels, Susan
TI – Interannual variability of the Indonesian Throughflow transport: A revisit based on 30 year expendable bathythermograph data
JO – Journal of Geophysical Research: Oceans
JA – J. Geophys. Res. Oceans
VL – 120
IS – 12
SN – 2169-9291
UR – http://dx.doi.org/10.1002/2015JC011351
DO – 10.1002/2015JC011351
SP – 8270
EP – 8282
KW – ITF
KW – ENSO
KW – IOD
KW – geostrophic transport
KW – planetary wave dynamics
KW – 4532 General circulation
KW – 4522 ENSO
KW – 4554 Planetary waves
KW – 4515 Deep recirculations
KW – 4262 Ocean observing systems
PY – 2015
AB – Based on 30 year repeated expendable bathythermograph (XBT) deployments between Fremantle, Western Australia, and the Sunda Strait, Indonesia, from 1984 to 2013, interannual variability of geostrophic transport of the Indonesian Throughflow (ITF) and its relationships with El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) are investigated. The IOD induced coastal Kelvin waves propagate along the Sumatra-Java coast of Indonesia, and ENSO induced coastal Kelvin waves propagate along the northwest coast of Australia, both influencing interannual variations of the ITF transport. The ITF geostrophic transport is stronger during La Niña phase and weaker during El Niño phase, with the Niño3.4 index leading the ITF variability by 7 months. The Indian Ocean wind variability associated with the IOD to a certain extent offset the Pacific ENSO influences on the ITF geostrophic transport during the developing and mature phases of El Niño and La Niña, due to the covarying IOD variability with ENSO. The ITF geostrophic transport experiences a strengthening trend of about 1 Sv every 10 years over the study period, which is mostly due to a response to the strengthening of the trade winds in the Pacific during the climate change hiatus period. Decadal variations of the temperature-salinity relationships need to be considered when estimating the geostrophic transport of the ITF using XBT data.
ER –

NR – 185
TY – JOUR
AU – Li, Jianping
AU – Sun, Cheng
AU – Jin, Fei-Fei
C8 – 2013GL057877
TI – NAO implicated as a predictor of Northern Hemisphere mean temperature multidecadal variability
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 40
IS – 20
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2013GL057877
DO – 10.1002/2013GL057877
SP – 5497
EP – 5502
KW – North Atlantic Oscillation
KW – Northern Hemisphere mean surface temperature
KW – multidecadal variability
KW – Atlantic Multidecadal Oscillation
KW – 1616 Climate variability
KW – 1620 Climate dynamics
KW – 3305 Climate change and variability
KW – 3309 Climatology
KW – 4513 Decadal ocean variability
PY – 2013
AB – The twentieth century Northern Hemisphere mean surface temperature (NHT) is characterized by a multidecadal warming-cooling-warming pattern followed by a flat trend since about 2000 (recent warming hiatus). Here we demonstrate that the North Atlantic Oscillation (NAO) is implicated as a useful predictor of NHT multidecadal variability. Observational analysis shows that the NAO leads both the detrended NHT and oceanic Atlantic Multidecadal Oscillation (AMO) by 15–20?years. Theoretical analysis illuminates that the NAO precedes NHT multidecadal variability through its delayed effect on the AMO due to the large thermal inertia associated with slow oceanic processes. An NAO-based linear model is therefore established to predict the NHT, which gives an excellent hindcast for NHT in 1971–2011 with the recent flat trend well predicted. NHT in 2012–2027 is predicted to fall slightly over the next decades, due to the recent NAO decadal weakening that temporarily offsets the anthropogenically induced warming.
ER –

NR – 186
TY – JOUR
T1 – Northwestern Pacific typhoon intensity controlled by changes in ocean temperatures
JF – Science Advances
JO – Sci Adv
DO – 10.1126/sciadv.1500014
VL – 1
IS – 4
AU – Mei, Wei
AU – Xie, Shang-Ping
AU – Primeau, François
AU – McWilliams, James C.
AU – Pasquero, Claudia
Y1 – 2015/05/01
UR – http://advances.sciencemag.org/content/1/4/e1500014.abstract
AB – Dominant climatic factors controlling the lifetime peak intensity of typhoons are determined from six decades of Pacific typhoon data. We find that upper ocean temperatures in the low-latitude northwestern Pacific (LLNWP) and sea surface temperatures in the central equatorial Pacific control the seasonal average lifetime peak intensity by setting the rate and duration of typhoon intensification, respectively. An anomalously strong LLNWP upper ocean warming has favored increased intensification rates and led to unprecedentedly high average typhoon intensity during the recent global warming hiatus period, despite a reduction in intensification duration tied to the central equatorial Pacific surface cooling. Continued LLNWP upper ocean warming as predicted under a moderate [that is, Representative Concentration Pathway (RCP) 4.5] climate change scenario is expected to further increase the average typhoon intensity by an additional 14% by 2100.
ER –

NR – 187
TY – JOUR
AU – Takahashi, Chiharu
AU – Watanabe, Masahiro
TI – Pacific trade winds accelerated by aerosol forcing over the past two decades
JA – Nature Climate Change
PY – 2016/04/25/online
VL – 6
SP – 768
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate2996
DO – 10.1038/nclimate2996
M3 –
L3 – https://www.nature.com/articles/nclimate2996#supplementary-information
AB – The Pacific trade winds, coupled with the zonal sea surface temperature gradient in the equatorial Pacific Ocean, control regional sea levels1, and therefore their trend is a great concern in the Pacific Rim. Over the past two decades, easterly winds have been accelerated in association with eastern tropical Pacific cooling2. They may represent natural interdecadal variability in the Pacific3 and possibly explain the recent global warming hiatus4,5,6,7. However, the intensification of the winds has been the strongest ever observed in the past century2,5,8, the reason for which is still unclear. Here we show, using multiple climate simulations for 1921–2014 by a global climate model, that approximately one-third of the trade-wind intensification for 1991–2010 can be attributed to changes in sulfate aerosols. The multidecadal sea surface temperature anomaly induced mostly by volcanic aerosols dominates in the western North Pacific, and its sign changed rapidly from negative to positive in the 1990s, coherently with Atlantic multidecadal variability9,10,11. The western North Pacific warming resulted in intensification of trade winds to the west of the dateline. These trends have not contributed much to the global warming hiatus, but have greatly impacted rainfall over the western Pacific islands.
ER –

NR – 188
TY – JOUR
AU – Li, Xichen
AU – Xie, Shang-Ping
AU – Gille, Sarah T.
AU – Yoo, Changhyun
TI – Atlantic-induced pan-tropical climate change over the past three decades
JA – Nature Climate Change
PY – 2015/11/02/online
VL – 6
SP – 275
EP –
PB – Nature Publishing Group
SN –
UR – http://dx.doi.org/10.1038/nclimate2840
DO – 10.1038/nclimate2840
M3 –
L3 – https://www.nature.com/articles/nclimate2840#supplementary-information
AB – During the past three decades, tropical sea surface temperature (SST) has shown dipole-like trends, with warming over the tropical Atlantic and Indo-western Pacific but cooling over the eastern Pacific. Competing hypotheses relate this cooling, identified as a driver of the global warming hiatus1,2, to the warming trends in either the Atlantic3,4 or Indian Ocean5. However, the mechanisms, the relative importance and the interactions between these teleconnections remain unclear. Using a state-of-the-art climate model, we show that the Atlantic plays a key role in initiating the tropical-wide teleconnection, and the Atlantic-induced anomalies contribute ~55–75% of the tropical SST and circulation changes during the satellite era. The Atlantic warming drives easterly wind anomalies over the Indo-western Pacific as Kelvin waves and westerly anomalies over the eastern Pacific as Rossby waves. The wind changes induce an Indo-western Pacific warming through the wind–evaporation–SST effect6,7, and this warming intensifies the La Niña-type response in the tropical Pacific by enhancing the easterly trade winds and through the Bjerknes ocean dynamical processes8. The teleconnection develops into a tropical-wide SST dipole pattern. This mechanism, supported by observations and a hierarchy of climate models, reveals that the tropical ocean basins are more tightly connected than previously thought.
ER –

NR – 189
TY – JOUR
T1 – Climate Signals in the Mid- to High-Latitude North Atlantic from Altimeter Observations
AU – Li, Feili
AU – Jo, Young-Heon
AU – Yan, Xiao-Hai
AU – Liu, W. Timothy
Y1 – 2015/06/16
PY – 2015
DA – 2016/07/01
N1 – doi: 10.1175/JCLI-D-12-00670.1
DO – 10.1175/JCLI-D-12-00670.1
T2 – Journal of Climate
JF – Journal of Climate
JO – J. Climate
SP – 4905
EP – 4925
VL – 29
IS – 13
PB – American Meteorological Society
AB – The variability of the sea surface height anomaly (SSHA) in the mid- to high-latitude North Atlantic for the period of 1993?2010 was investigated using the ensemble empirical mode decomposition to identify the dominant time scales. Sea level variations in the North Atlantic subpolar gyre (SPG) are dominated by the annual cycle and the long-term increasing trend. In comparison, the SSHA along the Gulf Stream (GS) is dominated by variability at intraseasonal and annual time scales. Moreover, the sea level rise in the SPG developed at a reduced rate in the 2000s compared to rates in the 1990s, which was accompanied by a rebound in SSHA variability following a period of lower variability in the system. These changes in both apparent trend and low-frequency SSHA oscillations reveal the importance of low-frequency variability in the SPG. To identify the possible contributing factors for these changes, the heat content balance (equivalent variations in the sea level) in the subpolar region was examined. The results indicate that horizontal circulations may primarily contribute to the interannual to decadal variations, while the air?sea heat flux is not negligible at annual time scale. Furthermore, the low-frequency variability in the SPG relates to the propagation of Atlantic meridional overturning circulation (AMOC) variations from the deep-water formation region to midlatitudes in the North Atlantic, which might have the implications for recent global surface warming hiatus.
SN – 0894-8755
M3 – doi: 10.1175/JCLI-D-12-00670.1
UR – https://doi.org/10.1175/JCLI-D-12-00670.1
Y2 – 2018/02/07
ER –

NR – 190
TY – JOUR
TI – How Long will the Pause of Global Warming Stay Again?
AU – Bin, Huang Jian
AU – Yong, Luo
AU – Wu, Wang Shao
AU – Yu, Wen Xin
AU – Ci, Zhao Zong
PY – 2014
JO – Progressus Inquisitiones De Mutatione Climatis
VL – 10
IS – 6
SP – 465
EP – 468
DO – 10.3969/j.issn.1673-1719.2014.06.011
ER –

NR – 191
TY – JOUR
AU – Veettil, Bijeesh Kozhikkodan
AU – Pereira, Sebastián Felipe Ruiz
AU – Wang, Shanshan
AU – Valente, Pedro Teixeira
AU – Grondona, Atilio Efrain Bica
AU – Rondón, Adriana Coromoto Becerra Rondón
AU – Rekowsky, Isabel Cristiane
AU – de Souza, Sergio Florêncio
AU – Bianchini, Nilceia
AU – Bremer, Ulisses Franz
AU – Simões, Jefferson Cardia
TI – Un análisis comparativo del comportamiento diferencial de los glaciares en los Andes Tropicales usando teledetección
T2 – A comparative analysis of glacier retreat in the Tropical Andes using remote sensing
PY – 2016
JO – Investigaciones Geográficas
VL – 51
SP – 3
EP – 36
DO – 10.5354/0719-5370.2016.41215
UR – https://investigacionesgeograficas.uchile.cl/index.php/IG/article/view/41215
AB – In this research paper, we analysed the behaviour of Tropical Andean glaciers in a changing climate. We used multi-source satellite images as well as meteorological datasets to achieve this objective. Representative glaciers in four different climatic zones, namely the inner tropics, northern wet outer tropics, southern wet outer tropics and dry outer tropics, were considered in this study. Changes in annual maximum snowline during 1985 – 2015 and also the decadal changes in the area between 1975 and 2015 of these glaciers were calculated. Furthermore, we analysed the rate of glacier retreat during the occurrence of El Niño–Southern Oscillation and Pacific Decadal Oscillation. It is observed that the glaciers in both the inner and outer tropics underwent retreat during the study period and most of this retreat occurred during 1975 – 1997 which is parallel with the so-called Pacific shift. Exceptional variations in snowline altitude were observed when an El Niño event occurs during the warm phase of the Pacific Decadal Oscillation. No significant signals of the recent hiatus in global warming were observed, except in the dry outer tropics which are situated near the subtropical region.
ER –

NR – 192
TY – JOUR
TI – The Global Warming Hiatus Simulated in HadGEM2-AO Based on RCP8.5
AU – Wie, Jieun
AU – Moon, Byung-Kwon
AU – Kim, Ki-Young
AU – Lee, Johan
PY – 2014
JO – Journal of the Korean earth science society
VL – 35
IS – 4
SP – 249
EP – 258
DO – 10.5467/JKESS.2014.35.4.249
UR – http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=JGGHBA_2014_v35n4_249
PB – The Korean Earth Science Society
AB – Despite the greenhouse gases like carbon dioxide have steadily increased in atmosphere, the overall trend of the global average surface air temperature has stalled during the last decade (2002-present). This phenomenon is often called hiatus or warming pause, which is challenging the prevailing view that anthropogenic forcing causes warming environment. Our study characterized the hiatus by analyzing the HadGEM2-AO (95 yrs) simulation data based on RCP8.5 scenario. The PC2 time series from the EOF of the zonal mean vertical ocean temperature has been defined as the index that represents the warming pause. The relationship between the hiatus, ENSO and the changes in climate system are identified by utilizing the newly defined PC2. Since the La Nina index (defined as the negative of NINO3 index) leads PC2 by about 11 months, it may be possible that the La Nina causes the warming to be interrupted. We also show that the cooling of the climate system closed tied to the heat penetration into the deep ocean, indicating the weakening the warming rate is due to the oceanic heat uptake. Finally, the global warming hiatus is characterized by the anomalous warming in Arctic region as well as the intensification of the trade wind in the equatorial Pacific.
ER –

NR – 193
TY – JOUR
TI – Linear and Nonlinear Trends of Extreme Temperatures in Korea
AU – Kim, Sang-Wook
AU – Song, Kanghyun
AU – Kim, Seo-Yeon
AU – Son, Seok-Woo
AU – Franzke, C.
JO – Atmosphere
SN – 1598-3560
VL – 24
IS – 3
SP – 379
EP – 390
KW – Quantile regression
KW – extreme surface air temperature
KW – long-term trend
PB – Korean Meteorological Society
PY – 2014/09
UR – http://www.dbpia.co.kr/Article/NODE02486406
AB – This study explores the long-term trends of surface air temperatures in 11 KMA stations over the period of 1960~2012. Both linear and nonlinear trends are examined for the 95th, 50th, and 5th percentiles of daily maximum (Tmax) and minimum temperatures (Tmin) by using quantile regression method. It is found that in most stations linear trends of Tmax and Tmin are generally stronger in winter than in summer, and warming trend of the 5th percentile temperature (cold extreme) is stronger than that of the 95th percentile temperature (warm extreme) in both seasons. The nonlinear trends, which are evaluated by the second order polynomial fitting, show a strong nonlinearity in winter. Specifically, winter temperatures have increased until 2000s but slightly decreased afterward in all percentiles. This contrasts with the 95th and 50th percentiles of summer Tmin that show a decreasing trend until 1980s then an increasing trend. While this result is consistent with a seasonal dependence of the recent global warming hiatus, most of the nonlinear trends are statistically insignificant, making a quantitative attribution of nonlinear temperature trends challenging.
ER –

NR – 194
TY – JOUR
TI – Enhanced Responses of Sea Surface Temperature over Offshore China to Global Warming and Hiatus
AU – Tan, Hongjian
AU – Cai, Rongshuo
AU – Huang, Ronghui
PY – 2016
JO – Advances in Climate Change Research
VL – 12
IS – 6
SP – 500
EP – 507
DO – 10.12006/j.issn.1673-1719.2016.038
UR – http://www.climatechange.cn/CN/abstract/abstract9266.shtml
AB – In this study, we assessed and compared the sea surface temperature (SST) trends between offshore China and other sea regions of interest as well as global mean surface temperature based on four SST datasets. The results revealed an enhanced SST response over offshore China during different periods. During the accelerated global warming periods (1980s and 1990s), SST over offshore China shows faster rising trend than the global mean. The most pronounced warming area is located over the East China Sea, with the rising rate up to 0.60? per decade, which is 5 times faster than that of the global mean. While during the hiatus period (1998-2014), SST over offshore China exhibits significant cooling trend. The decadal variability of offshore China SST is closely linked to the Pacific Decadal Oscillation (PDO). The periods with rapid warming (cooling) over offshore China are consistent with the positive (negative) phase of PDO. PDO may affect SST over offshore China through the East Asian Monsoon and Kuroshio Current.
ER –

NR – 195
TY – JOUR
TI – Research on the global warming Hiatus
AU – Lin, Xiaopei
AU – Xu, Lixiao
AU – Li, Jianping
AU – Luo, Dehai
AU – Liu, Hailong
PY – 2016
JO – Advances in Earth Science
VL – 31
IS – 10
SP – 995
EP – 1000
DO – 10.11867/j.issn.1001-8166.2016.10.0995
UR – http://www.adearth.ac.cn/article/2016/1001-8166-31-10-995.html
AB – A global warming “hiatus” has been observed since the beginning of the 21st century despite the increase in heat-trapping greenhouse gases, challenging the current global warming studies. Focusing on the phenomena and mechanisms of the global warming “hiatus”, the National Key Research Program of China launched a project in July, 2016. The main research themes of this project cover: ?Revealing the spatial and temporal variability of the global warming hiatus, and quantifying the contributions of external forcing and internal (natural) variability, respectively; ?Revealing the role of the atmosphere in the global heat and energy redistribution under global warming hiatus; ?Revealing the role of the ocean in the global heat and energy redistribution under global warming hiatus; ?Investigating the predictability of the global warming hiatus. The key scientific issues to be resolved include: ?Identifying characteristics of the global warming hiatus and discerning the roles of decadal, multi-decadal oscillations; ?Revealing the role of ocean-atmosphere dynamical processes in the global redistribution of heat and energy; ?Understanding the predictability of the global warming hiatus. The research aims to predict the future development of the global warming hiatus, and to point out the possible impacts on China and other important areas, including “The Belt and Road” core area and the Polar Regions.
ER –

NR – 196
TY – JOUR
TI – Research Progress on Hiatus in The Process of Global Warming
AU – Chen, Xingrong
AU – Cai Yi
AU – Tan Jing
AU – Wang Lei
PY – 2014
JO – Advances in Earth Science
VL – 29
IS – 8
SP – 947
EP – 955
UR – http://www.adearth.ac.cn/article/2014/1001-8166-29-8-0947.html
AB – In the 21st century, global warming hiatus has become a new hotspot in the research of climate change. This paper introduces the research progress on this phenomenon in detail, especially the validation studies of hiatus, research on the influence of the radiation forcing and the natural variability of the climate system due to air?sea interaction, and then puts forward several puzzles that still need to be solved on current research of hiatus. The paper particularly introduces the international major view, which think that the main reason of the hiatus in this century is that the strengthened trade wind on the background of the PDO negative phase leads to the warm water “accumulation”? in the equatorial western Pacific while the cooling in equatorial eastern Pacific causes the heat transferred down to the deep ocean. Therefore, hiatus phenomenon does not mean the stop of global warming, but just the heat transportation to the deep ocean, which is another manifestation of global warming.
ER –

NR – 197
TY – JOUR
TI – A review of recent studies on global warming hiatus
AU – Song, Bin
AU – Zhi, Xie-Fei
AU – Hu, Yao-Xing
PY – 2015
JO – Transactions of Atmospheric Sciences
VL – 38
IS – 2
SP – 145
EP – 154
DO – 10.13878/j.cnki.dqkxxb.20150105002
UR – http://www.wanfangdata.com.cn/details/detail.do?_type=perio&id=njqxxyxb201502001
AB – Since the industrial revolution, the content of anthropogenic greenhouse gas is increasing. As a result, the global surface air temperature grows rapidly. However, the global surface air temperature has stalled since 1998, despite the greenhouse gas steadily increases. This paper reviewed the latest research progress on this phenomenon, especially the mechanism of the global warming hiatus. There are two main viewpoints on the mechanism, namely, the external forcing and natural variability. The former includes the influence of solar activity, volcanic aerosol particles, man-made aerosol particles and stratospheric water vapor forcing. Scientists in the opinion of natural variability hold the idea that the missing heat produced by human activity has entered the deep ocean, especially the layer below 700 m. They believe that the oceans play a key role in the global warming hiatus. There are two main ideas for that: Pacific Decadal Oscillation (PDO), especially the cooling in the eastern tropical Pacific, and the Atlantic Meridional Overturning Circulation (AMOC). The widely accepted idea on the mechanism of recent global warming hiatus is natural variability. The missing heat has entered the deep ocean. But it still remains controversial which ocean basin gain the missing heat.
ER –

NR – 198
TY – JOUR
TI – Evolution of Surface Temperature during Global Warming Hiatus Based on Observations and CMIP5 Simulations
AU – He, Jinhai
AU – Zhan, Fengxing
AU – Qi, Li
AU – Wang, Di
PY – 2016
JO – Chinese Journal of Atmospheric Sciences
VL – 40
IS – 1
SP – 33
EP – 45
DO – 10.3878/j.issn.1006-9895.1409.14217
UR – http://www.dqkxqk.ac.cn/dqkx/dqkx/ch/html/20160105.htm
AB – The rise in global surface temperature has significantly declined after 2000. In this study, the evolution of the surface temperature of the global land-mean and Eurasia middle-high latitudes during the global warming hiatus was analyzed based on CRU observations. Simulations and projections were also evaluated using the Coupled Model Intercomparison Project 5 (CMIP5). The results indicate that, in the global warming hiatus period, the trend of the global land-mean surface temperature is only 0.14? (10 a)-1, which is half that during 1976-1999. The trend is less than that before 2000 in nine of the 13 global land regions, and four of them show a decreasing trend. The Eurasia middle-high latitude region is the most interesting among all the regions. For 1976-1999, the Eurasia middle-high latitude region shows the largest warming among all the land regions and reaches 0.50? (10 a)-1. After 2000, the trend significantly declines to -0.17? (10 a)-1, the greatest cooling trend over land, globally, contributing 49.13% of the remarkable change in global land surface temperatures before and after 2000. Furthermore, the surface temperature of the Eurasia middle-high latitude region shows an opposite change in autumn and winter after 2000; the temperature of the former rises by 0.86? (10 a)-1, while the that of the latter decreases by 2.68? (10 a)-1. In CMIP5, only the simulation and projects in BCC-CSM1.1 under the RCP2.6 scenario and MRI-ESM1 under the RCP8.5 scenario reproduce the evolution of the global land-mean and Eurasia middle-high latitude surface temperature, as well as the opposite change between autumn and winter of the Eurasia middle-high latitude region, during the global warming hiatus. The temperature projection of the BCC-CSM1.1 under the RCP2.6 scenario for the Eurasia middle-high latitude remains flat, near 1.2?, after 2012, and jumps to 2? after 2020. The change in the MRI-ESM1’s projected temperature under the RCP8.5 scenario is close to zero before 2030; the temperature then rises remarkably, to ? (10 a)-1.
ER –

NR – 199
TY – JOUR
TI – Hiatus of global warming: A review
AU – Su, Jingzhi
AU – Wen, Min
AU – Ding, Yihui
AU – Gao, Yongqi
AU – Song, Yafang
PY – 2016
JO – Chinese Journal of Atmospheric Sciences
VL – 40
IS – 6
SP – 1143
EP – 1153
DO – 10.3878/j.issn.1006-9895.1512.15242
UR – http://www.dqkxqk.ac.cn/dqkx/ch/reader/create_pdf.aspx?file_no=20160604&flag=1&journal_id=dqkx
ER –

NR – 200
TY – JOUR
TI – Debate on Global Warming “Hiatus”
AU – Zhao, Zongci
AU – Luo, Yong
AU – Huang, Jianbin
PY – 2016
JO – Climate Change Research
VL – 12
IS – 6
SP – 571
EP – 574
DO – 10.12006/j.issn.1673-1719.2016.055
UR – http://www.climatechange.cn/CN/10.12006/j.issn.1673-1719.2016.055
ER –

NR – 201
TY – JOUR
TI – Climate change science and sustainable development
AU – Qin, Dahe
PY – 2014
JO – Progress in Geography
VL – 33
IS – 7
SP – 874
EP – 883
DO – 10.11820/dlkxjz.2014.07.002
UR – http://www.progressingeography.com/CN/abstract/abstract14634.shtml
AB – Since the Fourth Assessment Report (AR4) was released by the Intergovernmental Panel on Climate Change (IPCC) in 2007, new observations have further proved that the warming of the global climate system is unequivocal. Each of the last three successive decades before 2012 has been successively warmer at global mean surface temperature than any preceding decade since 1850. 1983-2012 was likely the warmest 30-year period of the last 1400 years. From 1998 to 2012, the rate of warming of the global land surface slowed down, but it did not reflect the long-term trends in climate change. The ocean has warmed, and the upper 75 m of the ocean warmed by more than 0.11? per decade since 1970. Over the period of 1971 to 2010, 93% of the net energy increase in the Earth’s climate system was stored in the oceans. The rate of global mean sea level rise has accelerated, which was up to 3.2 mm yr-1 between 1993 and 2010. Anthropogenic global ocean carbon stocks were likely to have increased and caused acidification of the ocean surface water. Since 1971, the glaciers and the Greenland and Antarctic ice sheets have been losing mass. Since 1979, the Arctic sea ice extent deceased at 3.5% to 4.1% per decade, and the Antarctic sea ice extent in the same period increased by 1.2% to 1.8% per decade. The extent of the Northern Hemisphere snow cover has decreased. Since the early 1980s, the permafrost temperatures have increased in most regions. Human influence has been detected in the warming of the atmosphere and the ocean, changes in the water cycle, reductions in snow and ice, global mean sea level rise, and changes in climate extremes. The largest contribution to the increase in the anthropogenic radiative forcing was by the increase in the atmospheric concentration of CO2 since 1750. It led to more than half of global warming since the 1950s (with 95 % confidence). It is predicted using Coupled Model Intercomparison Project Phase 5 (CMIP5) and Representative Concentration Pathways (RCPs) that the global mean surface temperature will continue to rise for the end of this century, the frequency of extreme events such as heat waves and heavy precipitation will increase, and precipitation will present a trend of “the dry becomes drier, the wet becomes wetter”. The temperature of the upper ocean will increase by 0.6 to 2.0? compared to the period of 1986 to 2005, heat will penetrate from the surface to the deep ocean which will affect ocean circulation, and sea level will rise by 0.26 to 0.82 m in 2100. Cryosphere will continue to warm. To control global warming, humans need to reduce the greenhouse gas emissions. If the increase in temperature is higher than 2? than before industrialization, the mean annual economic losses worldwide will reach 0.2% to 2.0% of income, and cause large-scale irreversible effects, including death, disease, food insecurity, inland flooding and water logging, and rural drinking water and irrigation difficulties that affect human security. If taking prompt actions, however, it is still possible to limit the increase in temperature within 2?. To curb the gradually out-of-control global warming and achieve the goal of sustainable development of the human society, global efforts to reduce emissions are needed.
ER –

NR – 202
TY – JOUR
TI – Temperature mutation and globe warming stagnate study in typical area of Yellow River basin in recently 60years
AU – Huang, Xing
AU – Ma, Long
AU – Liu, Ting-xi
AU – Wang, Jing-ru
AU – Liu, Dan-hui
AU – Li, Hong-yu
PY – 2016
JO – China Environmental Science
VL – 36
IS – 11
SP – 3253
EP – 3262
UR – http://manu36.magtech.com.cn/Jweb_zghjkx/CN/abstract/abstract14853.shtml
AB – The part of Yellow River in Inner Mongolia was chosen as a typical area of Yellow River Basin. The regional annual average maximum temperature (AMaxT), annual average minimum temperature (AMinT) and annual average temperature (AvT) from 1951 to 2012 were selected and analyzed by Mann-Kendall method. The temperature variations before and after the mutation and the warming stagnate following the mutation were also discussed. Annual (or seasonal) AMinT mutation happened first on 1977 to 1987. Then the AvT and AMaxT mutation happened on 1978 to 1993 and 1978 to 1994, respectively. The mutation period of average autumn and winter temperature were same as AMaxT. The earliest intra-annual mutation was winter (1977 to 1978), and the latest was summer (1987 to 1994). The winter and AMaxT had more variations than summer and AMinT. The increase ratio or AMinT was 0.231~0.604?/10a which have the most contribution. All the annual (or seasonal) temperatures had a warming stagnate from 1997 to 2007 after the mutation, successively. The stagnate occurred in spring and not stagnate occurred in summer. Mostly annual and seasonal temperature stagnate happened later than the global period which winter firstly, then autumn, the AvT was the last one (on 2007). The AMaxT increase rate was lower in the period of after mutation and before stagnate. However, the decrease rate of AMaxT if faster after stagnate. The AMinT was on the contrary. This indicates that the AMinT was sensitive to temperature increase and the AMaxT was sensitive to the temperature decrease. In seasonal, the spring AMaxT increase rate is higher from mutation to stagnate, and the spring AMinT decrease rate was the fastest after the temperature stagnate which is -0.324?/a.
ER –

NR – 203
TY – JOUR
TI – Recent global-warming “hiatus” and its implications on the measures to be taken against global warming
AU – Junichi, Tsuitii
PY – 2014
JO – Energy and power
VL – 64
IS – 283
SP – 80
EP – 86
UR – http://ci.nii.ac.jp/naid/40020266117/
ER –

NR – 204
TY – JOUR
TI – Surface Temperature and Precipitation Variation of Pastoral Transitional Zone in Northern China during 1964-2013
AU – Zhao, Wei
AU – Wei, Zhigang
AU – Zheng, Zhiyuan
AU – Dong, Wenjie
PY – 2016
JO – Plateau Meteorology
VL – 35
IS – 4
SP – 979
EP – 988
DO – 10.7522/j.issn.1000-0534.2015.00079
UR – http://html.rhhz.net/gyqx/html/20160413.htm
AB – This study analyzed the spatial-temporal change of historical temperature and precipitation in pastoral transitional zone in Northern China, based on observational temperature and precipitation grid datasets during 1964-2013 from Chinese Meteorology Administration (CMA). The climate division was made using rotated empirical orthogonal function (REOF) in the meantime. The result shows that: (1) The whole pastoral transitional zone in Northern China can be divided into 4 regions which can be simply named the west region, the central region, the southern section of the east region, and the northern section of the east region, respectively. (2) In general, the pastoral transitional zone in Northern China had experienced a significant warming during 1964-2013 which was mainly attributed to the warming of winter and larger increase of minimum temperature rather than the increase of maximum temperature. The pastoral transitional zone in Northern China had also experienced a slightly decrease of precipitation (13 mm less during 1964-2013), and it was largely because the summer precipitation had declined the most in this period. (3) Focused on sub-regions, the temperature of the central region in pastoral transitional zone increased the most in the period of 1964-2013 among 4 sub-regions. As for the precipitation, annual precipitation in western north region decreased in the last 50 years mostly because of the decrease of spring precipitation in local. Meanwhile, the annual precipitation in central region and the southern section of the east region had decreased as well, but differently, it can be mainly attributed to the summer precipitation’s decline. Moreover, the annual precipitation increased in the northern section of the east region, and the spring precipitation contributed it the most. (4) The pastoral transitional zone in Northern China has experienced a warming hiatus resembling to the global warming hiatus since late 1990s, only the temperature has declined more, meaning that the declining trend of temperature in pastoral transitional zone is more obvious.
ER –

NR – 205
TY – JOUR
TI – Characteristics of Climate Change over the Tibetan Plateau Under the Global Warming During 1979-2014
AU – Duan, Anmin
AU – Xiao, Zhixiang
AU – Wu, Guoxiong
PY – 2016
JO – Advances in Climate Change Research
VL – 12
IS – 5
SP – 374
EP – 381
DO – 10.12006/j.issn.1673-1719.2016.039
UR – http://www.climatechange.cn/CN/Y2016/V12/I5/374
AB – Global warming has been a hot issue during recent decades, while the global warming hiatus since 1998 was detected as documented by many papers, meanwhile the Tibetan Plateau (TP) experiencing a rapid warming process. Based on previous studies, this paper mainly reviews the TP climate change under the global warming in four aspects: temperature, snow cover, precipitation and atmospheric apparent heat source, and points out that the accelerated warming over the TP results in the retreat of snow cover accompanied by the increase of precipitation. Though the TP heat source has been declined in recent decades whether based on observation or reanalysis datasets, it shows large uncertainties.
ER –

NR – 206
TY – JOUR
TI – CMIP5 climate model simulates the empirical study of global temperature change from 1850 to 2014
AU – Meng, Wei
AU – Fangli, Qiao
PY – 2016
JO – SCIENTIA SINICA Terrae
VL – 46
IS – 12
SP – 1675
EP – 1688
DO – 10.1360/N072015-00465
UR – http://engine.scichina.com/publisher/scp/journal/SSTe/46/12/10.1360/N072015-00465
ER –

NR – 207
TY – JOUR
T1 – The Community Earth System Model (CESM) Large Ensemble Project: A Community Resource for Studying Climate Change in the Presence of Internal Climate Variability
AU – Kay, J. E.
AU – Deser, C.
AU – Phillips, A.
AU – Mai, A.
AU – Hannay, C.
AU – Strand, G.
AU – Arblaster, J. M.
AU – Bates, S. C.
AU – Danabasoglu, G.
AU – Edwards, J.
AU – Holland, M.
AU – Kushner, P.
AU – Lamarque, J.-F.
AU – Lawrence, D.
AU – Lindsay, K.
AU – Middleton, A.
AU – Munoz, E.
AU – Neale, R.
AU – Oleson, K.
AU – Polvani, L.
AU – Vertenstein, M.
Y1 – 2014/11/19
PY – 2014
DA – 2015/08/01
N1 – doi: 10.1175/BAMS-D-13-00255.1
DO – 10.1175/BAMS-D-13-00255.1
JF – Bulletin of the American Meteorological Society
SP – 1333
EP – 1349
VL – 96
IS – 8
PB – American Meteorological Society
AB – While internal climate variability is known to affect climate projections, its influence is often underappreciated and confused with model error. Why? In general, modeling centers contribute a small number of realizations to international climate model assessments [e.g., phase 5 of the Coupled Model Intercomparison Project (CMIP5)]. As a result, model error and internal climate variability are difficult, and at times impossible, to disentangle. In response, the Community Earth System Model (CESM) community designed the CESM Large Ensemble (CESM-LE) with the explicit goal of enabling assessment of climate change in the presence of internal climate variability. All CESM-LE simulations use a single CMIP5 model (CESM with the Community Atmosphere Model, version 5). The core simulations replay the twenty to twenty-first century (1920?2100) 30 times under historical and representative concentration pathway 8.5 external forcing with small initial condition differences. Two companion 1000+-yr-long preindustrial control simulations (fully coupled, prognostic atmosphere and land only) allow assessment of internal climate variability in the absence of climate change. Comprehensive outputs, including many daily fields, are available as single-variable time series on the Earth System Grid for anyone to use. Early results demonstrate the substantial influence of internal climate variability on twentieth- to twenty-first-century climate trajectories. Global warming hiatus decades occur, similar to those recently observed. Internal climate variability alone can produce projection spread comparable to that in CMIP5. Scientists and stakeholders can use CESM-LE outputs to help interpret the observational record, to understand projection spread and to plan for a range of possible futures influenced by both internal climate variability and forced climate change.
SN – 0003-0007
M3 – doi: 10.1175/BAMS-D-13-00255.1
UR – https://doi.org/10.1175/BAMS-D-13-00255.1
Y2 – 2018/02/08
ER –

NR – 208
TY – JOUR
AU – Meehl, Gerald A.
AU – Teng, Haiyan
C8 – L22705
TI – Case studies for initialized decadal hindcasts and predictions for the Pacific region
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 39
IS – 22
SN – 1944-8007
UR – http://dx.doi.org/10.1029/2012GL053423
DO – 10.1029/2012GL053423
SP – n/a
EP – n/a
KW – decadal prediction
KW – decadal variability
KW – 1616 Climate variability
KW – 1620 Climate dynamics
KW – 1626 Global climate models
KW – 3305 Climate change and variability
KW – 4513 Decadal ocean variability
PY – 2012
AB – Case studies involving notable past decadal climate variability are analyzed for the mid-1970s climate shift, when the tropical Pacific warmed over a decade and globally averaged temperature rapidly increased, and the early 2000s hiatus when the tropical Pacific cooled over a decade and global temperatures warmed little. Ten year hindcasts following the CMIP5 decadal climate prediction experiment design are analyzed for those two periods using two different initialization techniques in a global coupled climate model, the CCSM4. There is additional skill in the initialized hindcasts for surface temperature patterns over the Pacific region for those two case studies over and above that in free-running historical simulations with the same model. A 30 year hindcast also shows added skill over the Pacific compared to the historical simulations. A 30 year prediction from the initialized model simulations shows less global warming for the 2016–2035 period than the free-running model projection for that same time period.
ER –

NR – 209
TY – JOUR
T1 – Anthropogenic CO2 warming challenged by 60-yearcycle
AU – Gervais, François
JO – Earth-Science Reviews
VL – 155
SP – 129
EP – 135
PY – 2016
DA – 2016/04/01/
SN – 0012-8252
DO – https://doi.org/10.1016/j.earscirev.2016.02.005
UR – http://www.sciencedirect.com/science/article/pii/S0012825216300277
KW – Transient climate response
KW – Anthropogenic greenhouse warming
KW – Seasonal CO oscillation
KW – Sea ice area
KW – Sea-level rise
KW – AMO
AB – Time series of sea-level rise are fitted by a sinusoid of period ~60years, confirming the cycle reported for the global mean temperature of the earth. This cycle appears in phase with the Atlantic Multidecadal Oscillation (AMO). The last maximum of the sinusoid coincides with the temperature plateau observed since the end of the 20th century. The onset of declining phase of AMO, the recent excess of the global sea ice area anomaly and the negative slope of global mean temperature measured by satellite from 2002 to 2015, all these indicators sign for the onset of the declining phase of the 60-yearcycle. Once this cycle is subtracted from observations, the transient climate response is revised downwards consistent with latest observations, with latest evaluations based on atmospheric infrared absorption and with a general tendency of published climate sensitivity. The enhancement of the amplitude of the CO2 seasonal oscillations which is found up to 71% faster than the atmospheric CO2 increase, focus on earth greening and benefit for crops yields of the supplementary photosynthesis, further minimizing the consequences of the tiny anthropogenic contribution to warming.
ER –

NR – 210
TY – JOUR
AU – Lorentzen, Torbjørn
PY – 2015
DA – 2015/02/01
TI – A statistical analysis of sea temperature data
JO – Theoretical and Applied Climatology
SP – 585
EP – 610
VL – 119
IS – 3
AB – The paper analyzes sea temperature series measured at two geographical locations along the coast of Norway. We address the question whether the series are stable over the sample period 1936–2012 and whether we can measure any signal of climate change in the regional data. We use nonstandard supF, OLS-based CUSUM, RE, and Chow tests in combination with the Bai-Perron’s structural break test to identify potential changes in the temperature. The augmented Dickey-Fuller, the KPSS, and the nonparametric Phillips-Perron tests are in addition applied in the evaluation of the stochastic properties of the series. The analysis indicates that both series undergo similar structural instabilities in the form of small shifts in the temperature level. The temperature at Lista (58° 06′ N, 06° 38′ E) shifts downward about 1962 while the Skrova series (68° 12′ N, 14° 10′ E) shifts to a lower level about 1977. Both series shift upward about 1987, and after a period of increasing temperature, both series start leveling off about the turn of the millennium. The series have no significant stochastic or deterministic trend. The analysis indicates that the mean temperature has moved upward in decadal, small steps since the 1980s. The result is in accordance with recent analyses of sea temperatures in the North Atlantic. The findings are also related to the so-called hiatus phenomenon where natural variation in climate can mask global warming processes. The paper contributes to the discussion of applying objective methods in measuring climate change.
SN – 1434-4483
UR – https://doi.org/10.1007/s00704-014-1119-x
DO – 10.1007/s00704-014-1119-x
ID – Lorentzen2015
ER –

NR – 211
TY – JOUR
AU – Li, Qingxiang
AU – Yang, Su
AU – Xu, Wenhui
AU – Wang, Xiaolan L.
AU – Jones, Phil
AU – Parker, David
AU – Zhou, Liming
AU – Feng, Yang
AU – Gao, Yun
C8 – 2014GL062773
TI – China experiencing the recent warming hiatus
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 42
IS – 3
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2014GL062773
DO – 10.1002/2014GL062773
SP – 889
EP – 898
KW – hiatus
KW – temperature
KW – climate change
KW – 1637 Regional climate change
KW – 1605 Abrupt/rapid climate change
KW – 1650 Solar variability
KW – 3309 Climatology
KW – 3305 Climate change and variability
PY – 2015
AB – Based on the homogenized data set, we analyze changes in mean temperature and some extreme temperature indices over China since 1961 and especially during the recent warming hiatus period (1998–2012) in a global average context. The result shows that the decrease of annual mean maximum has contributed most to the decreases in overall mean temperature and in diurnal temperature range (DTR) during the warming hiatus period. In most parts of China except the southwest, the summer mean maximum temperature (TxS) shows the largest increase, while the winter mean minimum temperature (TnW) indicates slight cooling trends. These changes have augmented the seasonal cycle and increased the likelihood of extreme warm and cold events. Further analyses reveal that the increases in TxS are significantly correlated with concurrent increases in solar radiation. In southwest China, the annual mean temperature, TxS, TnW, and DTR increased during 1998–2012, possibly related to increased dryness in this region during the hiatus period.
ER –

NR – 212
TY – JOUR
AU – Ueda, Hiroaki
AU – Kamae, Youichi
AU – Hayasaki, Masamitsu
AU – Kitoh, Akio
AU – Watanabe, Shigeru
AU – Miki, Yurisa
AU – Kumai, Atsuki
TI – Combined effects of recent Pacific cooling and Indian Ocean warming on the Asian monsoon
JA – Nature Communications
PY – 2015/11/13/online
VL – 6
SP – 8854
EP –
PB – The Author(s)
SN –
UR – http://dx.doi.org/10.1038/ncomms9854
DO – 10.1038/ncomms9854
M3 – Article
L3 – https://www.nature.com/articles/ncomms9854#supplementary-information
AB – Recent research indicates that the cooling trend in the tropical Pacific Ocean over the past 15 years underlies the contemporaneous hiatus in global mean temperature increase. During the hiatus, the tropical Pacific Ocean displays a La Niña-like cooling pattern while sea surface temperature (SST) in the Indian Ocean has continued to increase. This SST pattern differs from the well-known La Niña-induced basin-wide cooling across the Indian Ocean on the interannual timescale. Here, based on model experiments, we show that the SST pattern during the hiatus explains pronounced regional anomalies of rainfall in the Asian monsoon region and thermodynamic effects due to specific humidity change are secondary. Specifically, Indo-Pacific SST anomalies cause convection to intensify over the tropical western Pacific, which in turn suppresses rainfall in mid-latitude East Asia through atmospheric teleconnection. Overall, the tropical Pacific SST effect opposes and is greater than the Indian Ocean SST effect.
ER –

NR – 213
TY – JOUR
AU – Saffioti, Claudio
AU – Fischer, Erich M.
AU – Knutti, Reto
C8 – 2015GL063091
TI – Contributions of atmospheric circulation variability and data coverage bias to the warming hiatus
JO – Geophysical Research Letters
JA – Geophys. Res. Lett.
VL – 42
IS – 7
SN – 1944-8007
UR – http://dx.doi.org/10.1002/2015GL063091
DO – 10.1002/2015GL063091
SP – 2385
EP – 2391
KW – warming hiatus
KW – dynamical adjustment
KW – coverage bias
KW – atmospheric circulation
KW – internal climate variability
KW – natural climate variability
KW – 1616 Climate variability
KW – 1620 Climate dynamics
KW – 3305 Climate change and variability
KW – 3319 General circulation
PY – 2015
AB – The warming hiatus shows a strong seasonal and geographical asymmetry, with cooling in the Northern Hemisphere winter, especially over land, and warming elsewhere and in the other seasons. We show that the characteristics of the Northern Hemisphere winter cooling in 1998–2012 can mostly be explained by missing observations and by internal variability in the atmospheric circulation of the Northern Hemisphere extratropics. Estimates of the annual and seasonal temperature trends in 1998–2012 obtained by considering the concurrent effects of unforced natural variability and of coverage bias are much closer to the corresponding long-term trends. Reanalyses suggest that the coverage bias was exceptionally pronounced during recent years and that an area of strong warming was missed due to the incomplete observational coverage. Coupled Model Intercomparison Project Phase 5 climate models indicate that trends in atmospheric circulation during the hiatus period did not occur as a response to anthropogenic forcing.
ER –

NR – 214
TY – JOUR
T1 – Clarifying the Roles of Greenhouse Gases and ENSO in Recent Global Warming through Their Prediction Performance
AU – Triacca, Umberto
AU – Pasini, Antonello
AU – Attanasio, Alessandro
AU – Giovannelli, Alessandro
AU – Lippi, Marco
Y1 – 2014/08/26
PY – 2014
DA – 2014/10/01
DO – 10.1175/JCLI-D-13-00784.1
JF – Journal of Climate
JO – J. Climate
SP – 7903
EP – 7910
VL – 27
IS – 20
PB – American Meteorological Society
AB – It is well known that natural external forcings and decadal-to-millennial variability drove changes in the climate system throughout the Holocene. Regarding recent times, attribution studies have shown that greenhouse gases (GHGs) determined the trend of temperature (T) in the last half century, while circulation patterns contributed to modify its interannual, decadal, or multidecadal behavior over this period. Here temperature predictions based on vector autoregressive models (VARs) have been used to study the influence of GHGs and El Niño?Southern Oscillation (ENSO) on recent temperature behavior. It is found that in the last decades of steep temperature increase, ENSO shows just a very short-range influence on T, while GHGs are dominant for each forecast horizon. Conversely and quite surprisingly, in the previous quasi-stationary period the influences of GHGs and ENSO are comparable, even at longer range. Therefore, if the recent hiatus in global temperatures should persist into the near future, an enhancement of the role of ENSO can be expected. Finally, the predictive ability of GHGs is more evident in the Southern Hemisphere, where the temperature series is smoother.
SN – 0894-8755
UR – https://doi.org/10.1175/JCLI-D-13-00784.1
Y2 – 2018/02/08
ER –

NR – 215
TY – JOUR
T1 – The global warming hiatus’s irrelevance
JO – Science
SP – 1482
LP – 1483
DO – 10.1126/science.350.6267.1482-d
VL – 350
IS – 6267
AU – Wehner, Michael F.
AU – Easterling, David R.
Y1 – 2015/12/18
UR – http://science.sciencemag.org/content/350/6267/1482.4.abstract
ER –

NR – 216
TY – JOUR
AU – Quirk, Tom
PY – 2012
DA – 2012/11/01
TI – Did the global temperature trend change at the end of the 1990s?
JO – Asia-Pacific Journal of Atmospheric Sciences
SP – 339
EP – 344
VL – 48
IS – 4
AB – The apparent leveling of the global temperature time series at the end of the 1990s may represent a break in the upward trend. A study of the time series measurements for temperature, carbon dioxide, humidity and methane shows changes coincident with phase changes of the Atlantic and Pacific Decadal Oscillations. There are changes in carbon dioxide, humidity and methane measurement series in 2000. If these changes mark a phase change of the Pacific Decadal Oscillation then it might explain the global temperature behavior.
SN – 1976-7951
UR – https://doi.org/10.1007/s13143-012-0032-4
DO – 10.1007/s13143-012-0032-4
ID – Quirk2012
ER –

NR – 217
TY – JOUR
TI – Discussion of the case of the missing heat
AU – Parker, Albert
PY – 2014
JO – Nonlinear Engineering
VL – 3
IS – 4
SP – 247
EP – 253
DO – 10.1515/nleng-2014-0011
UR – http://www.degruyter.com/view/j/nleng.ahead-of-print/nleng-2014-0011/nleng-2014-0011.xml
AB – The sea level projection of a 1 meter rise for the 21st century depends on climate models that have projected a given amount of anthropogenic warming during the same period. However, these same climate models predicted a warming also from 2000 to 2014, which has not been seen in the global surface temperature. Researchers have proposed several solutions such as the fact that the “missing heat” was accumulated in the deep ocean. However, no evidences of a sufficient warming of the deep oceans have been observed. Other arguments has been proposed as well and found unsatisfactory. There is the opportunity that the “heat” is not “real” but “missing” or “hiding” somewhere. If the climate model projected “heat” that simply does not exist in reality in the first place, consequently the models overestimate the anthropogenicwarming and also the sea level projections for the 21st century are overestimated.
ER –

NR – 218
TY – JOUR
T1 – Expected halt in the current global warming trend?
AU – Njau, Ernest C.
JO – Renewable Energy
VL – 30
IS – 5
SP – 743
EP – 752
PY – 2005
DA – 2005/04/01/
SN – 0960-1481
DO – https://doi.org/10.1016/j.renene.2004.07.011
UR – http://www.sciencedirect.com/science/article/pii/S0960148104002939
AB – The variation patterns of global temperature were considerably turbulent from about 1870 up to 1940. Then just after 1940 these patterns underwent a sunspot-related change and adopted to relatively less turbulent variability. It is established here that these global temperature patterns are currently in the process of undergoing a sunspot-related change from the post-1940 relatively less turbulent variability back into relatively more turbulent variability. This apparently imminent state of more turbulent variability is expected to stop and at least slightly reverse the global warming trend, which has been going on since about 1965. Besides, it is shown separately that the mean of ‘global mean temperature variations’ reaches the next peak at about the year 2005 after which it will expectedly be on a decreasing trend. Finally, it is shown that, contrary to projections made in the Third IPCC Assessment Report, Greenland is currently in an ongoing cooling trend which is expected to last up to at least the year 2035.
ER –

NR – 219
TY – JOUR
TI – Why global warming went missing since the year 2000
AU – Parker, Albert
PY – 2013
JO – Nonlinear Engineering
VL – 2
IS – 3-4
SP – 129
EP – 135
DO – 10.1515/nleng-2013-0017
UR – http://www.degruyter.com/view/j/nleng.2013.2.issue-3-4/nleng-2013-0017/nleng-2013-0017.xml
AB – Over the period January 2004 to present, the seas have experienced the lack of any warming, as finally properly measured in the ARGO project where a global array of more than 3,600 free-drifting profiling floats has measured the temperature of the upper 2000 m of the sea as it was not possible before. The warming of the seas has been a negligible 1.1*10-3 °C/year on average over the layer 0 – 2000 dbar below the accuracy of the measure. Over the period January 2000 to present, the measured land and sea temperatures of the less reliable GISS, NCDC and HADCRUT4 data sets have shown a small warming of 4.2*10-3 °C/year on average. Same period, the climate models propose for the land and sea temperatures an unrealistic warming of 20.5*10-3 °C/year (average of CMIP3) and 18.2*10-3 °C/year (average of the CMIP5). The “inconvenient truth” is that climate models are predicting a warming when there is no warming rather than simply overestimating the warming as discussed so far. The paper presents the failed validation of the climate models since their introduction and suggests the reasons of their failure in the overrated effect of the changed composition of the atmosphere and the neglected natural oscillations.
ER –

NR – 220
TY – JOUR
TI – Key Issues on Debating about the Global Warming
AU – Wang, Shaowu
AU – Ge, Quansheng
AU – Wang, Fang
AU – Wen, Xinyu
AU – Huang, Jianbin
PY – 2010
JO – Advances in Earth Science
VL – 6
UR – http://en.cnki.com.cn/Article_en/CJFDTOTAL-DXJZ201006015.htm
AB – Key issues on debating about global warming are reviewed:?Does the global warming pause? The answer is not sure.The HadCRUT3 data show that the temperature during 1999-2008 increased only a little(0.07?/10a),but this decade is still the most warmest one among the last 30 years.However,the data from NASA GISS indicate that the temperature increased in the same period is higher(0.19?/10a).Thus,global surface temperature in recent years oscillates on a warm level.However,natural variability needs to be taken into consideration.?Does the global warming be caused fully by anthropogenic factors? The answer is no.ENSO,solar activity,volcanism,and thermohaline circulation can also exert impact in some extent on climate change,though the morden global warming may be mostly attributed to the increasing of greenhouse effect.However,the natural factors may sometimes overwhelm the anthropogenic effect in the interannual to interdecadal time scale.Specially,the solar activity factor should be given more attention.?Does the impact of global warming become more evident recently? The answer is yes.New observational datas indicate that the melting speed of glaciers and ice caps and rising speed of sea level in recent years have exceeded the related projections by IPCC 4th Assessment Report.Accordingly,the updated projection of the future sea level also increases.
ER –

NR – 221
TY – JOUR
TI – Mechanisms for the hiatus in global warming
AU – Tung, Ka-Kit
AU – Zhang, Rong
AU – Trenberth, Kevin E.
PY – 2014
JO – Engineering Sciences
VL – 2
DO – 10.3969/j.issn.1672-4178.2014.02.007
UR – http://d.wanfangdata.com.cn/periodical_zggckx-e201402007.aspx
AB – The observed global mean temperature is the highest on record for the past decade but has plateaued to form an apparent“hiatus”in global temperature rise,with an almost zero short-term trend. Several speakers presented results on the hiatus and suggested possible mechanisms.
ER –

NR – 222
TY – JOUR
TI – On the definition and identifiability of the alleged “hiatus” in global warming
AU – Lewandowsky, Stephan
AU – Risbey, James S.
AU – Oreskes, Naomi
JA – Scientific Reports
PY – 2015/11/24/online
VL – 5
SP – 16784
EP –
PB – The Author(s)
SN –
UR – http://dx.doi.org/10.1038/srep16784
L3 – 10.1038/srep16784
M3 – Article
L3 – https://www.nature.com/articles/srep16784#supplementary-information
AB – Recent public debate and the scientific literature have frequently cited a “pause” or “hiatus” in global warming. Yet, multiple sources of evidence show that climate change continues unabated, raising questions about the status of the “hiatus”. To examine whether the notion of a “hiatus” is justified by the available data, we first document that there are multiple definitions of the “hiatus” in the literature, with its presumed onset spanning a decade. For each of these definitions we compare the associated temperature trend against trends of equivalent length in the entire record of modern global warming. The analysis shows that the “hiatus” trends are encompassed within the overall distribution of observed trends. We next assess the magnitude and significance of all possible trends up to 25 years duration looking backwards from each year over the past 30 years. At every year during the past 30 years, the immediately preceding warming trend was always significant when 17 years (or more) were included in the calculation, alleged “hiatus” periods notwithstanding. If current definitions of the “pause” used in the literature are applied to the historical record, then the climate system “paused” for more than 1/3 of the period during which temperatures rose 0.6?K.
ER –

NR – 223
TY – JOUR
AU – Lempereur, Morine
AU – Limousin, Jean-Marc
AU – Guibal, Frédéric
AU – Ourcival, Jean-Marc
AU – Rambal, Serge
AU – Ruffault, Julien
AU – Mouillot, Florent
TI – Recent climate hiatus revealed dual control by temperature and drought on the stem growth of Mediterranean Quercus ilex
JO – Global Change Biology
JA – Glob Change Biol
VL – 23
IS – 1
SN – 1365-2486
UR – http://dx.doi.org/10.1111/gcb.13495
DO – 10.1111/gcb.13495
SP – 42
EP – 55
KW – basal area increment
KW – climate change
KW – climate hiatus
KW – climate–growth response
KW – drought
KW – growth duration
KW – growth phenology
KW – Quercus ilex
PY – 2017
AB – A better understanding of stem growth phenology and its climate drivers would improve projections of the impact of climate change on forest productivity. Under a Mediterranean climate, tree growth is primarily limited by soil water availability during summer, but cold temperatures in winter also prevent tree growth in evergreen forests. In the widespread Mediterranean evergreen tree species Quercus ilex, the duration of stem growth has been shown to predict annual stem increment, and to be limited by winter temperatures on the one hand, and by the summer drought onset on the other hand. We tested how these climatic controls of Q. ilex growth varied with recent climate change by correlating a 40-year tree ring record and a 30-year annual diameter inventory against winter temperature, spring precipitation, and simulated growth duration. Our results showed that growth duration was the best predictor of annual tree growth. We predicted that recent climate changes have resulted in earlier growth onset (-10 days) due to winter warming and earlier growth cessation (-26 days) due to earlier drought onset. These climatic trends partly offset one another, as we observed no significant trend of change in tree growth between 1968 and 2008. A moving-window correlation analysis revealed that in the past, Q. ilex growth was only correlated with water availability, but that since the 2000s, growth suddenly became correlated with winter temperature in addition to spring drought. This change in the climate–growth correlations matches the start of the recent atmospheric warming pause also known as the ‘climate hiatus’. The duration of growth of Q. ilex is thus shortened because winter warming has stopped compensating for increasing drought in the last decade. Decoupled trends in precipitation and temperature, a neglected aspect of climate change, might reduce forest productivity through phenological constraints and have more consequences than climate warming alone.
ER –

NR – 224
TY – JOUR
T1 – Briefing: How do we know the globe has warmed? What do we know about why?
AU – Thorne, Peter
Y1 – 2015/05/01
PY – 2015
DA – 2015/05/01
DO – 10.1680/feng.15.00003
JF – Proceedings of the Institution of Civil Engineers – Forensic Engineering
SP – 58
EP – 64
VL – 168
IS – 2
PB – ICE Publishing
AB – This briefing outlines the evidence from instrumental records that leads to an unequivocal finding that the world has warmed. It then goes on to address the underlying causes, showing that only through invoking the effects of humans can the last 50 years be adequately explained. Finally, it addresses the recent hiatus/pause in warming of global surface temperatures and the implications thereof.
SN – 2043-9903
UR – https://doi.org/10.1680/feng.15.00003
Y2 – 2018/02/08
ER –

NR – 225
TY – JOUR
TI – Characteristics of the Trends in the Global Tropopause Estimated From COSMIC Radio Occultation Data
T2 – IEEE Transactions on Geoscience and Remote Sensing
SP – 6813
EP – 6822
AU – P. Gao
AU – X. Xu
AU – X. Zhang
PY – 2015
KW – El Nino Southern Oscillation
KW – Global Positioning System
KW – atmospheric composition
KW – atmospheric temperature
KW – global warming
KW – ocean temperature
KW – oceanographic regions
KW – stratosphere
KW – troposphere
KW – AD 2006 07 to 2014 02
KW – Antarctica
KW – COSMIC radio occultation data
KW – ENSO
KW – El Nino-Southern Oscillation
KW – Montreal protocol
KW – Nino 3.4 sea surface temperature index
KW – constellation observing system
KW – global climate change
KW – global tropopause
KW – global warming
KW – gridded monthly mean global positioning system radio occultation data
KW – longitude-latitude grid cell
KW – north America coast
KW – north Pacific ocean
KW – southern Indian ocean
KW – spatial distribution
KW – stratospheric ozone recovery
KW – tropopause height
KW – tropopause parameters
KW – tropopause temperature
KW – western Europe
KW – Correlation
KW – Global Positioning System
KW – Market research
KW – Meteorology
KW – Ocean temperature
KW – Temperature distribution
KW – Terrestrial atmosphere
KW – Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC)
KW – Global Positioning System (GPS) radio occultation (RO)
KW – lapse rate tropopause (LRT)
KW – ozone recovery
KW – tropopause trend
DO – 10.1109/TGRS.2015.2449338
JO – IEEE Transactions on Geoscience and Remote Sensing
IS – 12
SN – 0196-2892
VO – 53
VL – 53
JA – IEEE Transactions on Geoscience and Remote Sensing
Y1 – Dec. 2015
AB – This paper discusses the variabilities and trends in the global tropopause based on the gridded monthly mean Global Positioning System radio occultation data from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission during July 2006-February 2014. We find that the tropopause height can reflect El Niño-Southern Oscillation (ENSO) events. The correlation coefficient between global tropopause height anomalies and the Niño 3.4 sea surface temperature index is 0.53, with a maximum correlation coefficient of 0.8 at a lag of three months. We present first the detailed investigations about the spatial distribution of trends in tropopause parameters in each 10° × 5° longitude-latitude grid cell over the globe and find that the rates of change in the tropopause parameters during this time period are high in some particular regions such as the Southern Indian Ocean, Antarctica, Western Europe, North Pacific, and the east coast of North America. An analysis of global monthly means of the tropopause parameters indicates a global tropopause height increase of 0.03 ± 2.36 m/year during 2006-2014, with a corresponding temperature increase of 0.020 ± 0.008°C/year, and a pressure increase of 0.11 ± 0.059 hPa/year. The upward trend of tropopause height is significantly weaker than that in the past years, which might be attributed to the expected stratospheric ozone recovery associated with the Montreal Protocol, the global warming slowdown, and the abnormal global climate change in recent years. The trends of the tropopause parameters are the most significant over the Southern Indian Ocean and Antarctica during September/October/November, which could be due to the stratospheric ozone recovery.
ER –

Advertisements

Posted in Climate claims, Climate science | Leave a Comment »

Flaws of Lüdecke & Weiss

Posted by Ari Jokimäki on January 11, 2018

Once again a paper that looks at solar-climate connection turns out to be deeply flawed. It contains bad methodology, bad result handling, bad conclusions, and a biased reference list.


Data handling process of Lüdecke & Weiss (2018).

A few months ago, a new paper was published by Lüdecke and Weiss (LW17). Both Lüdecke and Weiss are known climate change contrarians. Serious problems have been reported from their previous work, which used some of the same methods that were used in this new one. The new paper has been published by Bentham Open, which has somewhat questionable reputation.

Climate change contrarians are liking this of course and recently I also encountered the paper when it was shown to me as a proof for something. I decided to take a more thorough look at the paper.

The reference list

The first thing that jumps out from LW17 is the papers they cite in their introduction section. You can immediately see that their review of existing research is biased. They cite Scafetta but not his critics. They cite Svensmark but not his critics. They cite Friis-Christensen & Lassen but not their critics (even F-C & L themselves have later agreed that the findings they reported in the paper cited by LW17 were not correct). They cite lots of papers that suggest some kind of influence of the sun on Earth’s climate, but they leave the multitude of papers that state clearly that sun hasn’t caused current climate change almost un-cited.

The reference list of LW17 is quite long which suggests that they have been relatively thorough in trying to find lot of references that support their argumentation. It also hints to the possibility that the biased reference list is by design and not just an accident due to sloppy paper search.

The methods of the study

The methods section (sections “The Data” and “Spectral Analysis”) of LW17 contains some curious issues. Perhaps the worst aspect of the methods section is that they haven’t described all the methods they used. Their later sections contain many steps that haven’t been described with enough detail in the paper, such as making a representation of the temperature reconstruction from the three sine waves and the steps involved in solar variability – temperature comparison.

Moving on to the things they describe in the methods section, here’s a quote describing one step in the LW17 data processing:

For Bün, HADCRUT4 and Pet respectively the most recent years which show unusual deviations from the remaining reconstructions were also omitted.

This is a kind of thing I have seen climate change contrarians using in their fraud accusations. Yet, I have seen climate change contrarians claiming to have read this paper thoroughly and accepting it as truth without a question, and even defending it fiercely.

Another thing is how LW17 have adjusted the satellite data to HadCRUT4 data. They took 1979 values for each and then shifted satellite data so that their 1979 values were the same (I’m not 100% sure that they did it exactly like this – they don’t give the details – but I think that the process I described results in what they did). I think using only one year worth of data to align the two records is a bad idea. It’s especially bad because there was an El Niño in 1979-1980. El Niño generally shows up more in satellite records than in surface temperature records so using an El Niño year as a baseline creates a bias between the two records (the satellite record runs a bit low after this). I would have used several years of data to align the two records, 10 years for example. They also seem to use only one year data to align their source reconstructions together.

LW17 have used temperature reconstructions from all over the world. This is good. They have also adjusted each reconstruction to a common baseline. This is also good. Their method to create a global data set out of them is a bad one, though. They have computed a simple mean of the reconstructions for each year. There is no area averaging or anything but just a simple mean. To illustrate why this is bad, they have only three reconstructions from the Southern Hemisphere (SH) while they have dozens of reconstructions from the Northern Hemisphere (NH) (making their reconstruction practically a NH one instead a global one). This means that the three reconstructions from SH are strongly out-weighted by the NH reconstructions. In a global temperature reconstruction both hemispheres should have an equal weight but in LW17 they don’t have that, not even close.

Making the SH-NH imbalance even worse in LW17, two of the three reconstructions from SH only cover time-period from 1640 to 1987 and from 1640 to 1993 while they describe their reconstruction as “a global temperature mean G7 over the last 2000 years”. Furthermore, the only SH reconstruction covering the full 2000 years is an ice core based temperature reconstruction from Antarctica which has temporal resolution of 17 to 50 years while the NH records have annual resolution. Hence, most of the LW17 temperature reconstruction is lots of NH records + one bad resolution SH record.

In addition, all the proxies are from land areas but LW17 use global instrumental and satellite data which includes also ocean surface area. Yet another thing is that the NH reconstructions in LW17 seem to be somewhat clustered around North Atlantic, which is a region known to show the Medieval Warm Period very clearly. Overall, the LW17 temperature reconstruction is a strange mix of reconstructions patched together with very questionable methods, and it really is just a NH reconstruction with an emphasis on North Atlantic region.

For the solar activity, LW17 use only one reconstruction that has been constructed from different sources. They seem to use the reconstruction as it is without tampering with it, which seems to be a good thing in the light of what was seen above.

The results of the study

In their analysis, LW17 concentrate on cycles only and mainly to past climate, so the study has only little relevance to current climate change. Causes of past climate changes do not mean that greenhouse gases couldn’t cause climate change now, and the presence of cycles in Earth’s climate don’t negate the effects of greenhouse gases, but climatic cycles and greenhouse gas forcing can (and do) co-exist.

LW17 don’t offer much new to sun-climate connection knowledge either because their main result is a possible correlation between the two which doesn’t offer any information other than solar variability might have an effect on Earth’s climate, which we knew already anyway.

But in addition to general insignificance of the study and the problems identified in the previous sections, there are further problems in the results section of the paper.

LW17 perform a Fourier transformation to their temperature reconstruction and then they select three strongest peaks from the Fourier transformation result. However, from their Figure 2 can be seen that one of the selected peaks (the 1000-year peak) is not statistically significant (it doesn’t exceed what they call “false alarm line”) while some of the statistically significant peaks (~65 year and ~50 year peaks) were not selected. LW17 do not discuss the issue. They just state that they have selected the three strongest peaks.

Next, LW17 use the three selected peaks to do an inverse Fourier transform. The result of this is a representation of their original temperature reconstruction. This hasn’t been described in the methods section, and they don’t also describe it in the results section adequately. They only mention that they have done an inverse Fourier transformation.

They compute a correlation between the original temperature reconstruction and the sine wave representation. Resulting correlation is quite good, but it doesn’t mean much because they correlate an original series with a series that has been constructed from the original series. In practice, they just compute a correlation between two representations of a same signal. This would be okay if they would have just used the correlation to check that the temperature reconstruction from the three sine waves is a reasonably good representation of the original reconstruction, and then proceed with the actual analysis, but they seem to treat the correlation value as one of their most important results, and there’s no further analysis with the inverse Fourier representation.

LW17 continue their analysis under the section “Sun’s Activity and Climate”. For many readers, it probably will not be a surprise that this section also contains problems.

In this section, LW17 first discuss the Fourier transformation results of solar activity proxy series they are using. Their discussion is a stub one. Based on the peaks found, they mention that the three peaks selected from the temperature reconstruction can also be seen in solar activity series. Below is an excerpt of their Figure 2.

The Table 2 (T2) of LW17 claims to show “Strongest spectral peaks for the records Chr, Bün, McK, Vill-N, Vill-S, Pet, G7, and Stei for periods > 700 years, from 700 to 300 years, from 300 to 100 years, and < 100 years”. From the figure above it can be seen that this is not the case. Highest peak of series “Pet” (ice core record from Antarctica) is very close to 0 (corresponding roughly to a wavelength of several thousand years) and the mentioned peak in T2 seems to be a double peak of which the weaker one seems to be better match in wavelength with the peak mentioned in T2. The mentioned peak of 499 years in T2 also seems to be a double peak and here better match seems also to be the weaker one. For both of the double peaks, it is of course difficult to estimate the situation from the graph, but it does seem that LW17 have selected the weaker ones of the mentioned double peaks to T2.

The series “Stei” (the solar activity proxy series) also shows stronger peaks than the ones mentioned in T2. Above 700 years there are two peaks clearly stronger than the mentioned 991-year peak. Also from 700 to 300 years there is one higher peak than the mentioned one.

The figure above shows also that it is easy to find matches for peaks when there are plenty of peaks to choose from. Highlighted is the selection of the peak in “Stei” that corresponds to the 188-year peak in “G7” (and in “Pet”). There are weaker peaks that are closer matches to the wavelength of 188-year peak than the highlighted 203-year peak. One of these is also clearly statistically significant at about 197 years.

Moving on past the selection of solar activity peaks, it should be noted that after LW17 have selected the peaks, they don’t do much about them. They don’t construct a representation of temperature and calculate correlations or anything like they did for temperature series but instead they just mention that the solar activity “shows the same periods” as temperature reconstruction based on the values presented in T2.

One further thing about the figure above, the solar activity series “Stei” shows lot of peaks and as discussed above, some of them are more meaningful than the ones LW17 emphasize. Why those peaks do not show up in the temperature reconstruction? This point has not been discussed by LW17.

Next step is a very curious one. They proceed to check the solar-climate connection further, but for some reason they drop their temperature reconstruction G7 and start using “Pet” which is the low-resolution ice core proxy from Antarctica. They don’t justify this at all.

The method they use here is not described in detail. They only mention that they do a “wavelet analysis”. At the end, however, their analysis here doesn’t extend beyond studying “eyesight similarities”.

Conclusion

In their introduction section, LW17 created a false picture of the situation of current research status of the solar activity – climate connection by citing mostly papers that support LW17 argumentation and ignoring most of the papers that show results against their argumentation. They did a not-even-half-baked analysis containing lot of flaws. In their conclusion section LW17 then suggested that their flawed results are a “confirmation” for the false picture created in the introduction section.

We can also wonder what was the point of the Fourier-inverse Fourier exercise LW17 did (with subsequent eyesight “analysis”), because if you want to demonstrate a solar-temperature correlation, then why not just compute a correlation between them directly? It is curious that they didn’t do this at least as a side-note, surely it would (or should?) have been interesting also to them.

In my opinion, LW17 is throughout bad science – biased citing, bad research methods, strange interpretation of results, etc. Having seen and studied the paper, I cannot help wondering what this quote from LW17 acknowledgements section means: “We express our thanks to the referees for valuable comments.” If the referees gave valuable comments and the resulting paper still is as bad as described above, how bad was this paper originally?

Posted in Climate claims | 5 Comments »

Some curious things about Svensmark et al. reference list

Posted by Ari Jokimäki on December 22, 2017

The hypothesis of significant effect of cosmic-rays to climate has been shown wrong many times. This is a pet hypothesis of Henrik Svensmark, who continues to push papers on the subject to scientific journals. A few days ago, the journal Nature Communications published a paper of Svensmark (& co-workers). I checked out its reference list because I think that some indicators of the quality of a paper can be found simply by checking the reference list, and how references are used.

S17 reference list – first impressions

I immediately noticed a few things about S17 reference list. I made some tweets (@AGWobserver) where I mention them:

The Kulmala et al. paper I mention there is this one: “Atmospheric data over a solar cycle: no connection between galactic cosmic rays and new particle formation”. It shows results against Svensmark’s hypothesis, but it is not cited by S17. The mentioned paper list in my tweets is this one: “Papers on the non-significant role of cosmic rays in climate”.

(Note added December 27, 2017: This paragraph is incorrect – S17 cites two Laakso et al. papers and I somehow got them mixed.) One Kulmala team paper S17 cites is “Detecting charging state of ultra-fine particles: instrumental development and ambient measurements” (Laakso et al. 2007). S17 uses it in this context: “Cosmic rays are the main producers of ions in Earth’s lower atmosphere21.” (21 is the S17 reference list number for the Laakso et al. paper.) This is strange because Laakso et al. don’t say anything about cosmic rays. Cosmic rays are mentioned only in their reference list in the title of Eichkorn et al. (2002) paper, and Laakso et al. refer to it in this context: “Ion mass spectrometers have been used successfully in the studies of new particle formation in the upper atmosphere (Eichkorn et al., 2002).” Furthermore, as Svensmark’s cosmic ray hypothesis relies on ion induced nucleation, it is noteworthy that one of Laakso et al. conclusions is this: “During a large fraction of days considered here, the contribution of ion-induced nucleation to the total nucleation rate was either negligible or relatively small.” To me it seems that either S17 is citing a wrong paper here, or then the cosmic ray ion production thing is implicitly in Laakso et al. results and I just don’t see it.

S17 reference list – comparison with other paper

I decided to look S17 reference list further. I chose a comparison paper, Gordon et al. (2017, “G17”), which is a research paper on the same issue than S17. Both papers have been published and submitted to their journals during 2017, S17 in May 10 and G17 in March 24, so S17 is a bit newer in that sense. S17 was published in December 19 and G17 in August 24, so also in that sense S17 is newer. I emphasize newer here because it suggests that references in S17 reference list should be as new or newer as references in G17 reference list.

The reference list of S17 contains 39 entries while the reference list of G17 contains 85 entries. As the papers are on the same subject, it seems that S17 reference list is a little short. However, scope of G17 seems to be somewhat broader, so reference list length doesn’t necessarily tell anything.

I also compared the temporal distributions of papers in the reference lists of these two papers. Result can be seen in this graph:

It is quite clear from the graph that S17 reference list focuses on older papers than G17 reference list. highest peak of temporal distribution of S17 is 2005-2009, while corresponding highest peak of G17 is 2010-2014. Also, G17 distribution is rather sharply concentrated on the more recent times, while S17 distribution is more spread out in time, and it almost seems as if the most resent research is being avoided in S17 reference list (the share of 2015-2017 papers is very low in S17 compared to G17).

Posted in Climate claims | 3 Comments »

Papers on the warming hole of the United States

Posted by Ari Jokimäki on February 8, 2017

This is a list of papers on the warming hole of the United States. The list is not complete, and will most likely be updated in future in order to make it more thorough and more representative.

The United States “warming hole”: quantifying the forced aerosol response given large internal variability (Banerjee et al. 2017)
Abstract: “Twenty-five years of large summer cooling over the southeastern United States ending in the mid-1970s coincided with rapidly increasing anthropogenic aerosol emissions. Here, we assess the claim that the cooling in that period was predominantly due to such aerosols. We utilize two 50-member sets of coupled climate model simulations, one with only anthropogenic aerosol forcings and another with all known natural and anthropogenic forcings, together with a long control integration. We show that, in the absence of aerosol forcing, none of the model simulations capture the observed surface cooling rate (∼0.56∘C decade−1), whereas with increasing aerosol emissions two (of fifty) of the simulations do. More importantly, however, we find that the cooling from aerosols (0.20° C decade−1) is insufficient to explain the observation. Our results therefore suggest that, while aerosols may have played a role, the observed cooling was a rare event that contained a large contribution from unforced internal variability.”
Citation: Banerjee A., L.M Polvani, and J.C. Fyfe (2017), The United States “warming hole’: quantifying the forced aerosol response given large internal variability, Geophys. Res. Lett., 44, doi:10.1002/2016GL071567.

Tracking regional temperature projections from the early 1990s in light of variations in regional warming, including ‘warming holes’ (Grose et al. 2017)
Abstract: “The perception of the accuracy of regional climate projections made in the early 1990s about climate change by 2030 may be influenced by how the temperature trend has changed in the 25 years since their publication. However, temperature trends over this period were influenced not only by external forcings such as greenhouse gases but also natural variations. The temperature of Southern Australia, the Sahel, South Asia and Southern Europe are currently within the warming estimates from statements in the early 1990s from the IPCC and CSIRO, assuming a linear trend between 1990 and 2030. However, northern Australia and central North America are currently at the lower limit or below these projections, having featured areas of multi-year regional cooling during global warming, sometimes called ‘warming holes’. Recent climate model simulations suggest that cooling can be expected in the recent past and near future in some regions, including in Australia and the US, and that cooling is less likely over 1990–2030 than in 1990–2015, bringing observations closer to the IPCC and CSIRO warming estimates by 2030. Cooling at the 25-year scale in some regions can be associated with cyclic variability such as the Inter-decadal Pacific Oscillation, or low trend such as in the Southern Ocean. Explicitly communicating the variability in regional warming rates in climate projections, including the possibility of regional warming ‘holes’ (or the opposite of ‘surges’ or ‘peaks’) would help to set more reliable expectations by users of those projections.”
Citation: Grose, M.R., Risbey, J.S. & Whetton, P.H. Climatic Change (2017) 140: 307. doi:10.1007/s10584-016-1840-9.

North Pacific SST Forcing on the Central United States “Warming Hole” as Simulated in CMIP5 Coupled Historical and Uncoupled AMIP Experiments (Pan et al. 2017)
Abstract: “The central United States experienced a cooling trend during the twentieth century, called the “warming hole,” most notably in the last quarter of the century when global warming accelerated. The coupled simulations of the models that participated in the Coupled Model Intercomparison Project, Phases 3 and 5 (CMIP3/5), have been unable to reproduce this abnormal cooling phenomenon satisfactorily. An unrealistic representation of the observed phasing of the Pacific Decadal Oscillation (PDO)—one of the proposed forcing mechanisms for the warming hole—in the models is considered to be one of the main causes of this effect. The CMIP5’s uncoupled Atmospheric Model Intercomparison Project (AMIP) experiment, whose duration approximately coincides with the peak warming hole cooling period, provides an opportunity, when compared with the coupled historical experiment, to examine the role of the variation in Pacific Ocean sea surface temperature (SST) in the warming hole’s formation and also to assess the skill of the models in simulating the teleconnection between Pacific SST and the continental climate in North America. Accordingly, this study compared AMIP and historical runs in the CMIP5 suite thereby isolating the role of SST forcing in the formation of the warming hole and its maintenance mechanisms. It was found that, even when SST forcing in the AMIP run was “perfectly” prescribed in the models, the skill of the models in simulating the warming hole cooling in the central United States showed little improvement over the historical run, in which SST is calculated interactively, even though the AMIP run overestimated the anti-correlation between temperature in the central United States and the PDO index. The fact that better simulation of the PDO phasing in the AMIP run did not translate into an improved summer cooling trend in the central United States suggests that the inability of the coupled CMIP5 models to reproduce the warming hole under the historical run is not mainly a result of the mismatch between simulated and observed PDO phasing, as believed.”
Citation: Zaitao Pan, Chunhua Shi, Sanjiv Kumar, and Zhiqiu Gao (2017) Atmosphere-Ocean, doi: 10.1080/07055900.2016.1261690.

Disappearance of the southeast U.S. “warming hole” with the late 1990s transition of the Interdecadal Pacific Oscillation (Meehl et al. 2015) [FULL TEXT]
Abstract: “Observed surface air temperatures over the contiguous U.S. for the second half of the twentieth century showed a slight cooling over the southeastern part of the country, the so-called “warming hole,” while temperatures over the rest of the country warmed. This pattern reversed after 2000. Climate model simulations show that the disappearance of the warming hole in the early 2000s is likely associated with the transition of the Interdecadal Pacific Oscillation (IPO) phase from positive to negative in the tropical Pacific in the late 1990s, coincident with the early 2000s slowdown of the warming trend in globally averaged surface air temperature. Analysis of a specified convective heating anomaly sensitivity experiment in an atmosphere-only model traces the disappearance of the warming hole to negative sea surface temperature anomalies and consequent negative precipitation and convective heating anomalies in the central equatorial Pacific Ocean associated with the negative phase of the IPO after 2000.”
Citation: Meehl, G. A., J. M. Arblaster, and C. T. Y. Chung (2015), Disappearance of the southeast U.S. “warming hole” with the late 1990s transition of the Interdecadal Pacific Oscillation, Geophys. Res. Lett., 42, 5564–5570, doi:10.1002/2015GL064586.

Sedimentary proxy evidence of a mid-Holocene hypsithermal event in the location of a current warming hole, North Carolina, USA (Tanner et al. 2015) [FULL TEXT]
Abstract: “A wetland deposit from the southern Appalachian mountains of North Carolina, USA, has been radiocarbon dated and shows continuous deposition from the early Holocene to the present. Non-coastal records of Holocene paleoenvironments are rare from the southeastern USA. Increased stable carbon isotope ratios (δ13C) of sedimentary organic matter and pollen percentages indicate warm, dry early- to mid-Holocene conditions. This interpretation is also supported by n-alkane biomarker data and bulk sedimentary C/N ratios. These warm, dry conditions coincide with a mid-Holocene hypsithermal, or altithermal, documented elsewhere in North America. Our data indicate that the southeastern USA warmed concurrently with much of the rest of the continent during the mid-Holocene. If the current “warming hole” in the southeastern USA persists, during a time of greenhouse gas-induced warming elsewhere, it will be anomalous both in space and time.”
Citation: Benjamin R. Tanner, Chad S. Lane, Elizabeth M. Martin, Robert Young, Beverly Collins (2015) Quaternary Research, Volume 83, Issue 2, March 2015, Pages 315–323, doi: 10.1016/j.yqres.2014.11.004.

Attribution of the United States “warming hole”: Aerosol indirect effect and precipitable water vapor (Yu et al. 2014) [FULL TEXT]
Abstract: “Aerosols can influence the climate indirectly by acting as cloud condensation nuclei and/or ice nuclei, thereby modifying cloud optical properties. In contrast to the widespread global warming, the central and south central United States display a noteworthy overall cooling trend during the 20th century, with an especially striking cooling trend in summertime daily maximum temperature (Tmax) (termed the U.S. “warming hole”). Here we used observations of temperature, shortwave cloud forcing (SWCF), longwave cloud forcing (LWCF), aerosol optical depth and precipitable water vapor as well as global coupled climate models to explore the attribution of the “warming hole”. We find that the observed cooling trend in summer Tmax can be attributed mainly to SWCF due to aerosols with offset from the greenhouse effect of precipitable water vapor. A global coupled climate model reveals that the observed “warming hole” can be produced only when the aerosol fields are simulated with a reasonable degree of accuracy as this is necessary for accurate simulation of SWCF over the region. These results provide compelling evidence of the role of the aerosol indirect effect in cooling regional climate on the Earth. Our results reaffirm that LWCF can warm both winter Tmax and Tmin.”
Citation: Shaocai Yu, Kiran Alapaty, Rohit Mathur, Jonathan Pleim, Yuanhang Zhang, Chris Nolte, Brian Eder, Kristen Foley & Tatsuya Nagashima (2014), Scientific Reports, 4, doi:10.1038/srep06929.

Multidecadal Climate Variability and the “Warming Hole” in North America: Results from CMIP5 Twentieth- and Twenty-First-Century Climate Simulations (Kumar et al. 2013) [FULL TEXT]
Abstract: “The ability of phase 5 of the Coupled Model Intercomparison Project (CMIP5) climate models to simulate the twentieth-century “warming hole” over North America is explored, along with the warming hole’s relationship with natural climate variability. Twenty-first-century warming hole projections are also examined for two future emission scenarios, the 8.5 and 4.5 W m−2 representative concentration pathways (RCP8.5 and RCP4.5). Simulations from 22 CMIP5 climate models were analyzed, including all their ensemble members, for a total of 192 climate realizations. A nonparametric trend detection method was employed, and an alternative perspective emphasizing trend variability. Observations show multidecadal variability in the sign and magnitude of the trend, where the twentieth-century temperature trend over the eastern United States appears to be associated with low-frequency (multidecadal) variability in the North Atlantic temperatures. Most CMIP5 climate models simulate significantly lower “relative power” in the North Atlantic multidecadal oscillations than observed. Models that have relatively higher skill in simulating the North Atlantic multidecadal oscillation also are more likely to reproduce the warming hole. It was also found that the trend variability envelope simulated by multiple CMIP5 climate models brackets the observed warming hole. Based on the multimodel analysis, it is found that in the twenty-first-century climate simulations the presence or absence of the warming hole depends on future emission scenarios; the RCP8.5 scenario indicates a disappearance of the warming hole, whereas the RCP4.5 scenario shows some chance (10%–20%) of the warming hole’s reappearance in the latter half of the twenty-first century, consistent with CO2 stabilization.”
Citation: Sanjiv Kumar, James Kinter, Paul A. Dirmeyer, Zaitao Pan, Jennifer Adams (2013), Journal of Climate, 26, 11, 3511-3527, doi: 10.1175/JCLI-D-12-00535.1.

Intermodel Variability and Mechanism Attribution of Central and Southeastern U.S. Anomalous Cooling in the Twentieth Century as Simulated by CMIP5 Models (Pan et al. 2013) [FULL TEXT]
Abstract: “Some parts of the United States, especially the southeastern and central portion, cooled by up to 2°C during the twentieth century, while the global mean temperature rose by 0.6°C (0.76°C from 1901 to 2006). Studies have suggested that the Pacific decadal oscillation (PDO) and the Atlantic multidecadal oscillation (AMO) may be responsible for this cooling, termed the “warming hole” (WH), while other works reported that regional-scale processes such as the low-level jet and evapotranspiration contribute to the abnormity. In phase 3 of the Coupled Model Intercomparison Project (CMIP3), only a few of the 53 simulations could reproduce the cooling. This study analyzes newly available simulations in experiments from phase 5 of the Coupled Model Intercomparison Project (CMIP5) from 28 models, totaling 175 ensemble members. It was found that 1) only 19 out of 100 all-forcing historical ensemble members simulated negative temperature trend (cooling) over the southeast United States, with 99 members underpredicting the cooling rate in the region; 2) the missing of cooling in the models is likely due to the poor performance in simulating the spatial pattern of the cooling rather than the temporal variation, as indicated by a larger temporal correlation coefficient than spatial one between the observation and simulations; 3) the simulations with greenhouse gas (GHG) forcing only produced strong warming in the central United States that may have compensated the cooling; and 4) the all-forcing historical experiment compared with the natural-forcing-only experiment showed a well-defined WH in the central United States, suggesting that land surface processes, among others, could have contributed to the cooling in the twentieth century.”
Citation: Zaitao Pan, Xiaodong Liu, Sanjiv Kumar, Zhiqiu Gao, James Kinter (2013) Journal of Climate, 26, 17, 6215-6237, doi: 10.1175/JCLI-D-12-00559.1.

Mechanisms Contributing to the Warming Hole and the Consequent U.S. East–West Differential of Heat Extremes (Meehl et al. 2012) [FULL TEXT]
Abstract: “A linear trend calculated for observed annual mean surface air temperatures over the United States for the second-half of the twentieth century shows a slight cooling over the southeastern part of the country, the so-called warming hole, while temperatures over the rest of the country rose significantly. This east–west gradient of average temperature change has contributed to the observed pattern of changes of record temperatures as given by the ratio of daily record high temperatures to record low temperatures with a comparable east–west gradient. Ensemble averages of twentieth-century climate simulations in the Community Climate System Model, version 3 (CCSM3), show a slight west–east warming gradient but no warming hole. A warming hole appears in only several ensemble members in the Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel dataset and in one ensemble member of simulated twentieth-century climate in CCSM3. In this model the warming hole is produced mostly from internal decadal time-scale variability originating mainly from the equatorial central Pacific associated with the Interdecadal Pacific Oscillation (IPO). Analyses of a long control run of the coupled model, and specified convective heating anomaly experiments in the atmosphere-only version of the model, trace the forcing of the warming hole to positive convective heating anomalies in the central equatorial Pacific Ocean near the date line. Cold-air advection into the southeastern United States in winter, and low-level moisture convergence in that region in summer, contribute most to the warming hole in those seasons. Projections show a disappearance of the warming hole, but ongoing greater surface temperature increases in the western United States compared to the eastern United States.”
Citation: Gerald A. Meehl, Julie M. Arblaster, Grant Branstator (2012) Journal of Climate, 25, 18, 6394-6408, doi: 10.1175/JCLI-D-11-00655.1.

Can CGCMs Simulate the Twentieth-Century “Warming Hole” in the Central United States? (Kunkel et al. 2006) [FULL TEXT]
Abstract: “The observed lack of twentieth-century warming in the central United States (CUS), denoted here as the “warming hole,” was examined in 55 simulations driven by external historical forcings and in 19 preindustrial control (unforced) simulations from 18 coupled general circulation models (CGCMs). Twentieth-century CUS trends were positive for the great majority of simulations, but were negative, as observed, for seven simulations. Only a few simulations exhibited the observed rapid rate of warming (cooling) during 1901–40 (1940–79). Those models with multiple runs (identical forcing but different initial conditions) showed considerable intramodel variability with trends varying by up to 1.8°C century−1, suggesting that internal dynamic variability played a major role at the regional scale. The wide range of trend outcomes, particularly for those models with multiple runs, and the small number of simulations similar to observations in both the forced and unforced experiments suggest that the warming hole is not a robust response of contemporary CGCMs to the estimated external forcings. A more likely explanation based on these models is that the observed warming hole involves external forcings combined with internal dynamic variability that is much larger than typically simulated. The observed CUS temperature variations are positively correlated with North Atlantic (NA) sea surface temperatures (SSTs), and both NA SSTs and CUS temperature are negatively correlated with central equatorial Pacific (CEP) SSTs. Most models simulate rather well the connection between CUS temperature and NA SSTs. However, the teleconnections between NA and CEP SSTS and between CEP SSTs and CUS temperature are poorly simulated and the models produce substantially less NA SST variability than observed, perhaps hampering their ability to reproduce the warming hole.”
Citation: Kenneth E. Kunkel, Xin-Zhong Liang, Jinhong Zhu, and Yiruo Lin (2006) Journal of Climate, 19, 17, 4137-4153, doi: 10.1175/JCLI3848.1.

Altered hydrologic feedback in a warming climate introduces a “warming hole” (Pan et al. 2004) [FULL TEXT]
Abstract: “In the last 25 years of the 20th century most major land regions experienced a summer warming trend, but the central U.S. cooled by 0.2–0.8 K. In contrast most climate projections using GCMs show warming for all continental interiors including North America. We examined this discrepancy by using a regional climate model and found a circulation-precipitation coupling under enhanced greenhouse gas concentrations that occurs on scales too small for current GCMs to resolve well. Results show a local minimum of warming in the central U.S. (a “warming hole”) associated with changes in low-level circulations that lead to replenishment of seasonally depleted soil moisture, thereby increasing late-summer evapotranspiration and suppressing daytime maximum temperatures. These regional-scale feedback processes may partly explain the observed late 20th century temperature trend in the central U.S. and potentially could reduce the magnitude of future greenhouse warming in the region.”
Citation: Pan, Z., R. W. Arritt, E. S. Takle, W. J. Gutowski Jr., C. J. Anderson, and M. Segal (2004), Altered hydrologic feedback in a warming climate introduces a “warming hole”, Geophys. Res. Lett., 31, L17109, doi:10.1029/2004GL020528.

General circulation model simulations of recent cooling in the east-central United States (Robinson et al. 2002) [FULL TEXT]
Abstract: “In ensembles of retrospective general circulation model (GCM) simulations, surface temperatures in the east-central United States cool between 1951 and 1997. This cooling, which is broadly consistent with observed surface temperatures, is present in GCM experiments driven by observed time varying sea-surface temperatures (SSTs) in the tropical Pacific, whether or not increasing greenhouse gases and other time varying climate forcings are included. Here we focus on ensembles with fixed radiative forcing and with observed varying SST in different regions. In these experiments the trend and variability in east-central U.S. surface temperatures are tied to tropical Pacific SSTs. Warm tropical Pacific SSTs cool U.S. temperatures by diminishing solar heating through an increase in cloud cover. These associations are embedded within a year-round response to warm tropical Pacific SST that features tropospheric warming throughout the tropics and regions of tropospheric cooling in midlatitudes. Precipitable water vapor over the Gulf of Mexico and the Caribbean and the tropospheric thermal gradient across the Gulf Coast of the United States increase when the tropical Pacific is warm. In observations, recent warming in the tropical Pacific is also associated with increased precipitable water over the southeast United States. The observed cooling in the east-central United States, relative to the rest of the globe, is accompanied by increased cloud cover, though year-to-year variations in cloud cover, U.S. surface temperatures, and tropical Pacific SST are less tightly coupled in observations than in the GCM.”
Citation: Robinson, W. A., R. Reudy, and J. E. Hansen, General circulation model simulations of recent cooling in the east-central United States, J. Geophys. Res., 107(D24), 4748, doi:10.1029/2001JD001577, 2002.

Posted in Climate claims, Climate science | Leave a Comment »

Global warming hiatus claims prebunked in 1980s and 1990s

Posted by Ari Jokimäki on January 17, 2017

Recent global warming hiatus has been a subject of intensive studies during the last ten years. But it seems that there already was some research on global warming hiatus during 1980s and 1990s (earliest studies on the issue were actually back in 1940s-1970s). This seems to have gone largely unnoticed in the scientific literature of current global warming hiatus, and it certainly seems to have gone unnoticed by climate mitigation opponents who have made claims on global warming hiatus since at least 2006 and still continue to do so.

Some time ago I stumbled on a few old papers which discussed the temperature evolution of 1940s to 1970s. In the early 20th century there had been warming which seemed to have stopped around 1940 until it continued again in the turn of 1970s and 1980s. Here I will use “global warming moratorium” to describe this early hiatus (reason for this can be found below). Below I’ll go through some of the papers in question.

Early studies on the 1940s-1970s global warming moratorium

Global surface temperature increased during the first half of the 20th century. In 1940s, this warming apparently stopped. Possibly the first to notice this was Kincer (1946):

Up to the end of 1945, records for 13 subsequent years have become available, and these are here presented, supplementary to the original data, to determine tendencies since 1932. They show that the general upward temperature trend continued for several years but that the more recent records indicate a leveling off, and even contain currently a suggestion of an impending reversal.

This was confirmed by Mitchell (1961, 1963), as described by Wigley et al. (1985):

Mitchell (1961, 1963) extended Willett’s analysis beyond 1940, improved the method of area averaging, and found that the warming prior to 1940 had subsequently become a cooling trend (as suggested earlier by Kincer [1946]).

Later, Mitchell (1970) studied the effect of anthropogenic forcings (carbon dioxide and aerosols) on the temperature evolution of 20th century. Mitchell noted on the carbon dioxide forcing:

Changes of mean atmospheric temperature due to CO2, calculated by Manabe et al. as 0.3°C per 10% change in CO2, are sufficient to account for only about one third of the observed 0.6°C warming of the earth between 1880 and 1940, but will probably have become a dominant influence on the course of planetary average temperature changes by the end of this century.

And on the global warming moratorium:

Although changes of total atmospheric dust loading may possibly be sufficient to account for the observed 0.3°C-cooling of the earth since 1940, the human-derived contribution to these loading changes is inferred to have played a very minor role in the temperature decline.

Reitan (1974) extended the temperature analysis to 1968 and reported that the global warming moratorium had continued. Brinkmann (1976) extended the analysis to 1973 and saw the first signs of global warming moratorium ending and warming resuming.

Wigley et al. (1985) mention one further point worth mentioning about the global warming moratorium:

All seasons show the same long-term trends, trends that are also common to all other land-based data sets: a warming from the 1880s to around 1940, cooling to the mid-1960s/early-1970s (less obvious in winter), and subsequent warming, beginning later in summer and autumn than in spring and winter.

According to Wigley et al. (1985), the global warming moratorium remained largely unexplained, although there had been some relatively successful attempts to explain the short-term variability in the surface temperature by volcanic aerosols and solar variations, see for example the discussion and analysis in Hansen et al. (1981) and in Gilliland (1982).

Oceans and surface temperature studies in 1980s

Watts (1985) used a simple model to suggest that changes in the rate of the deep water formation can have an effect to surface temperature:

…variations in the rate of formation of deep water can lead to fluctuations in the globally averaged surface temperature similar in magnitude to variations in the earth’s surface-air temperature that have occurred during the last several hundred years.

Gaffin et al. (1986) got similar results:

The largest features of the northern hemispheric surface land temperature record can be simulated with our climate and deep ocean feedback formulation and CO2 forcing alone.

Jones et al. (1987) studied the rapidity of carbon dioxide induced climate change. Within this study, they also looked at how changes in deep water formation affected warming caused by carbon dioxide. They created a simulation, where there was a global warming caused by carbon dioxide, and then they turned off the deep water formation in the Northern Hemisphere (because the global warming moratorium was strongest in Northern Hemisphere). This resulted in surface cooling right after the deep water formation was stopped, and later warming continued again.

In the late 1980s and early 1990s there were some other similar studies also.

The global warming moratorium discussion of early 1990s

So, it seems that at the turn of 1980s and 1990s there had been several studies suggesting that oceans could have considerable effect on the surface temperature. At this point, there was a discussion in the scientific literature on the global warming moratorium, and this discussion has some interesting resemblance to the current global warming hiatus discussion.

Watts and Morantine (1991), in an editorial of Springer’s journal Climatic Change, reviewed the research which I already have discussed above. They noted the possibility of energy transfer between the surface and the deep ocean and concluded:

It is entirely possible that the greenhouse gas climate change signal is alive and well and hiding in the ocean intermediate waters, having reached there because of increased upwelling, or by some other mechanism that could effectively transport heat from the upper layers of the ocean into the huge thermal reservoir of the intermediate and deep ocean.

Kellogg (1993) revisited the issue, also in the same journal, with a letter named as “An Apparent Moratorium on the Greenhouse Warming Due to the Deep Ocean”. Kellogg described some new observational evidence for the ocean’s role in the issue. Based on this he suggested:

…oceans could sequester a significant part of the incremental greenhouse-generated heat over a period of a few decades, a period during which the surface warming would be curtailed.

Kellogg also discussed some issues relating to timing of the global warming moratorium and what would have happened if oceans wouldn’t have had a role in the surface temperature. Relating to the current global warming hiatus discussion, Kellogg made an interesting note:

One of the arguments most frequently advanced by the skeptics is that the observed warming in this century should have been larger, based on climate models that do not take account of ocean circulations, and that there should theoretically have been no such ‘moratorium’ between 1940 and 1975.

Kellogg then notes that if the oceans played a role, there wouldn’t be such a problem.

Watts and Morantine (1993) also revisited the issue (perhaps the journal sent them Kellogg’s letter and asked for their response). There were couple of additional interesting points in their response relating to current discussion on global warming hiatus. They noted on the significance of the moratorium:

In a recent article by Galbraith and Green (1992), a series of statistical tests were performed on the global average temperature time series from 1880 to 1988 (Hansen and Lebedeff, 1987). A statistically significant trend that can be approximated by a linear term was found, and the deviation from this trend during the period between 1940 and 1970 was found to fall within the range of sample fluctuation.

And:

Even though the surface temperature of the Earth is an important piece of information, the distribution of thermal energy is a three-dimensional problem.

What I have shown here is just a sample of all papers that were studying the issue. The research on the issue also continued after the papers presented here.

The significance for current hiatus discussion

It is clear that before 2000s there had been lot of research on the subject of short-term variability of surface temperature in a presence of long-term warming trend. The research back then also pointed to probable causes of the short-term variability.

Apparently, the first claims of global warming hiatus after 1998 were made in 2006 by well-known climate change mitigation opponents. This was obviously far too soon statistically to make those claims, and there was no indication that the claims were made with knowledge of the earlier discussion and research on the subject. It also should be noted, that the claims in question were not made in scientific literature but in popular media (a situation that has continued after that and largely continues even today).

However, lots and lots of papers have been published on the recent global warming hiatus. I have sampled the reference lists of some of them and it seems that also scientific community has largely forgot that the issue has already been studied. This seems a bit unfortunate and makes one wonder if we will have forgotten the current research when the next moratorium or pause or hiatus or whatever happens.

References:

Waltraud A.R. Brinkmann (1976), Surface temperature trend for the Northern Hemisphere-updated, Quaternary Research, Volume 6, Issue 3, September 1976, Pages 355-358, doi:10.1016/0033-5894(67)90002-6.
http://www.sciencedirect.com/science/article/pii/0033589467900026

Gaffin, S. R., M. I. Hoffert, and T. Volk (1986), Nonlinear coupling between surface temperature and ocean upwelling as an agent in historical climate variations, J. Geophys. Res., 91(C3), 3944–3950, doi:10.1029/JC091iC03p03944.
http://onlinelibrary.wiley.com/doi/10.1029/JC091iC03p03944/full

Gilliland, R.L. (1982), Solar, volcanic, and CO2 forcing of recent climatic changes, Climatic Change, 4: 111. doi:10.1007/BF00140585.
http://rd.springer.com/article/10.1007/BF00140585

J. Hansen, D. Johnson, A. Lacis, S. Lebedeff, P. Lee, D. Rind, G. Russell (1981) Climate Impact of Increasing Atmospheric Carbon Dioxide, Science 28 Aug 1981: Vol. 213, Issue 4511, pp. 957-966, DOI: 10.1126/science.213.4511.957.
http://science.sciencemag.org/content/213/4511/957
http://people.oregonstate.edu/~schmita2/Teaching/ATS421-521/2015/papers/hansen81sci.pdf

P. D. Jones, T. M. L. Wigley, , S. C. B. Raper (1986), The Rapidity of CO2-Induced Climatic Change: Observations, Model Results and Palaeoclimatic Implications, in Abrupt Climatic Change, Volume 216 of the series NATO ASI Series pp 47-55.
http://rd.springer.com/chapter/10.1007/978-94-009-3993-6_4

Kellogg, W.W. (1993), An apparent moratorium on the greenhouse warming due to the deep ocean, Climatic Change 25: 85. doi:10.1007/BF01094085.
http://rd.springer.com/article/10.1007%2FBF01094085

Kincer, J. B. (1946), Our changing climate, Eos Trans. AGU, 27(3), 342–347, doi:10.1029/TR027i003p00342.
http://onlinelibrary.wiley.com/doi/10.1029/TR027i003p00342/abstract

Mitchell, J. M. (1961), RECENT SECULAR CHANGES OF GLOBAL TEMPERATURE. Annals of the New York Academy of Sciences, 95: 235–250. doi:10.1111/j.1749-6632.1961.tb50036.x
http://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.1961.tb50036.x/abstract

J. Murray Mitchell Jr. (1970), A Preliminary Evaluation of Atmospheric Pollution as a Cause of the Global Temperature Fluctuation of the Past Century, 139-155. In, S.F. Singer (ed.), Global Effects of Environmental Pollution. Springer Verlag, New York, New York.
http://rd.springer.com/chapter/10.1007/978-94-010-3290-2_15

Clayton H. Reitan (1974), A climatic model of solar radiation and temperature change, Quaternary Research, Volume 4, Issue 1, March 1974, Pages 25–38, http://dx.doi.org/10.1016/0033-5894(74)90061-1.
http://www.sciencedirect.com/science/article/pii/0033589474900611

Watts, R. G. (1985), Global climate variation due to fluctuations in the rate of deep water formation, J. Geophys. Res., 90(D5), 8067–8070, doi:10.1029/JD090iD05p08067.
http://onlinelibrary.wiley.com/doi/10.1029/JD090iD05p08067/full

Watts, R.G. & Morantine, M.C. (1991), Is the greenhouse gas-climate signal hiding in the deep ocean?, Climatic Change 18: iii. doi:10.1007/BF00142966.
http://rd.springer.com/article/10.1007%2FBF00142966

Wigley, T.M.L., Angell, J.K. and Jones, P.D., 1985. Analysis of the temperature record. In: M.C. MacCracken and F.M. Luther (Eds.), Detecting the Climatic Effects of Increasing Carbon Dioxide, (DOE/ER-0235), U.S. Department of Energy, Carbon Dioxide Research Division, Washington, D.C., 55-90.
http://archives.aaas.org/docs/Detecting_Climate_Effects_Increasing_CO2.pdf

Posted in AGW evidence, Climate claims, Climate science | Leave a Comment »

New research – temperature (October 18, 2016)

Posted by Ari Jokimäki on October 18, 2016

Some of the latest papers on temperature (related to climate) are shown below. First a few highlighted papers with abstracts and then a list of some other papers. If this subject interests you, be sure to check also the other papers – they are by no means less interesting than the highlighted ones.

Highlights

Comparing tropospheric warming in climate models and satellite data (Santer et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0333.1

Abstract: We use updated and improved satellite retrievals of the temperature of the mid- to upper troposphere (TMT) to address key questions about the size and significance of TMT trends, agreement with model-derived TMT values, and whether models and satellite data show similar vertical profiles of warming. A recent study claimed that TMT trends over 1979 and 2015 are three times larger in climate models than in satellite data, but did not correct for the contribution TMT trends receive from stratospheric cooling. Here we show that the average ratio of modeled and observed TMT trends is sensitive to both satellite data uncertainties and to model-data differences in stratospheric cooling. When the impact of lower stratospheric cooling on TMT is accounted for, and when the most recent versions of satellite datasets are used, the previously claimed ratio of three between simulated and observed near-global TMT trends is reduced to ≈ 1.7. Next, we assess the validity of the statement that satellite data show no significant tropospheric warming over the last 18 years. This claim is not supported by our analysis: in five out of six corrected satellite TMT records, significant global-scale tropospheric warming has occurred within the last 18 years. Finally, we address long-standing concerns regarding discrepancies in modeled and observed vertical profiles of warming in the tropical atmosphere. We show that amplification of tropical warming between the lower and mid- to upper troposphere is now in close agreement in the average of 37 climate models and in one updated satellite record.

Deep and Abyssal Ocean Warming from 35 years of Repeat Hydrography (Desbruyères et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL070413/abstract

Abstract: Global and regional ocean warming deeper than 2000 m is investigated using 35 years of sustained repeat hydrographic survey data starting in 1981. The global long-term temperature trend below 2000 m, representing the time period 1991–2010, is equivalent to a mean heat flux of 0.065 ± 0.040 W m−2 applied over the Earth’s surface area. The strongest warming rates are found in the abyssal layer (4000–6000 m), which contributes to one third of the total heat uptake with the largest contribution from the Southern and Pacific Oceans. A similar regional pattern is found in the deep layer (2000–4000 m), which explains the remaining two thirds of the total heat uptake yet with larger uncertainties. The global average warming rate did not change within uncertainties pre-2000 versus post-2000, whereas ocean average warming rates decreased in the Pacific and Indian Oceans and increased in the Atlantic and Southern Oceans.

The contribution of greenhouse gases to the recent slowdown in global-mean temperature trends (Checa-Garcia et al. 2016) http://iopscience.iop.org/article/10.1088/1748-9326/11/9/094018/meta

Abstract: The recent slowdown in the rate of increase in global-mean surface temperature (GMST) has generated extensive discussion, but little attention has been given to the contribution of time-varying trends in greenhouse gas concentrations. We use a simple model approach to quantify this contribution. Between 1985 and 2003, greenhouse gases (including well-mixed greenhouse gases, tropospheric and stratospheric ozone, and stratospheric water vapour from methane oxidation) caused a reduction in GMST trend of around 0.03–0.05 K decade−1 which is around 18%–25% of the observed trend over that period. The main contributors to this reduction are the rapid change in the growth rates of ozone-depleting gases (with this contribution slightly opposed by stratospheric ozone depletion itself) and the weakening in growth rates of methane and tropospheric ozone radiative forcing. Although CO2 is the dominant greenhouse gas contributor to GMST trends, the continued increase in CO2 concentrations offsets only about 30% of the simulated trend reduction due to these other contributors. These results emphasize that trends in non-CO2 greenhouse gas concentrations can make significant positive and negative contributions to changes in the rate of warming, and that they need to be considered more closely in analyses of the causes of such variations.

The Stancari air thermometer and the 1715–1737 record in Bologna, Italy (Camuffo et al. 2016) http://rd.springer.com/article/10.1007%2Fs10584-016-1797-8

Abstract: This paper is focused on the closed-tube Stancari air thermometer that was developed at the beginning of the eighteenth century as an improvement of the Amontons thermometer, and used to record the temperature in Bologna, Italy, from 1715 to 1737. The problems met with this instrument, its calibration and the building technology in the eighteenth century are discussed in order to correct the record. The used methodological approach constitutes a useful example for other early series. The analysis of this record shows that the temperature in Bologna was not different from the 1961–1990 reference period. This result is in line with the contemporary record taken in Padua, Italy, confirming that this period of the Little Ice Age was not cold in the Mediterranean area.

Twenty-five winters of unexpected Eurasian cooling unlikely due to Arctic sea-ice loss (McCusker et al. 2016) http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2820.html

Abstract: Surface air temperature over central Eurasia decreased over the past twenty-five winters at a time of strongly increasing anthropogenic forcing and Arctic amplification. It has been suggested that this cooling was related to an increase in cold winters due to sea-ice loss in the Barents–Kara Sea. Here we use over 600 years of atmosphere-only global climate model simulations to isolate the effect of Arctic sea-ice loss, complemented with a 50-member ensemble of atmosphere–ocean global climate model simulations allowing for external forcing changes (anthropogenic and natural) and internal variability. In our atmosphere-only simulations, we find no evidence of Arctic sea-ice loss having impacted Eurasian surface temperature. In our atmosphere–ocean simulations, we find just one simulation with Eurasian cooling of the observed magnitude but Arctic sea-ice loss was not involved, either directly or indirectly. Rather, in this simulation the cooling is due to a persistent circulation pattern combining high pressure over the Barents–Kara Sea and a downstream trough. We conclude that the observed cooling over central Eurasia was probably due to a sea-ice-independent internally generated circulation pattern ensconced over, and nearby, the Barents–Kara Sea since the 1980s. These results improve our knowledge of high-latitude climate variability and change, with implications for our understanding of impacts in high-northern-latitude systems.

Other papers

New method of estimating temperatures near the mesopause region using meteor radar observations (Lee et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL071082/abstract

Estimated influence of urbanization on surface warming in Eastern China using time-varying land use data (Liao et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/joc.4908/abstract

The influence of winter and summer atmospheric circulation on the variability of temperature and sea ice around Greenland (Ogi et al. 2016) http://www.tellusa.net/index.php/tellusa/article/view/31971

A cold and fresh ocean surface in the Nordic Seas during MIS 11: Significance for the future ocean (Kandiano et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL070294/abstract

Observed and projected sea surface temperature seasonal changes in the Western English Channel from satellite data and CMIP5 multi-model ensemble (L’Hévéder et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/joc.4882/abstract

Historical ocean reanalyses (1900–2010) using different data assimilation strategies (Yang et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/qj.2936/abstract

Analysis of the warmest Arctic winter, 2015-2016 (Cullather et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL071228/abstract

The influence of synoptic circulations and local processes on temperature anomalies at three French observatories (Dione et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/JAMC-D-16-0113.1

Ocean atmosphere thermal decoupling in the eastern equatorial Indian ocean (Joseph et al. 2016) http://link.springer.com/article/10.1007%2Fs00382-016-3359-1

Changes of the time-varying percentiles of daily extreme temperature in China (Li et al. 2016) http://rd.springer.com/article/10.1007%2Fs00704-016-1938-z

High atmospheric horizontal resolution eliminates the wind-driven coastal warm bias in the southeastern tropical Atlantic (Milinski et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL070530/abstract

Effects of Natural Variability of Seawater Temperature, Time Series Length, Decadal Trend and Instrument Precision on the Ability to Detect Temperature Trends (Schlegel & Smit, 2016) http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0014.1

Interhemispheric SST gradient trends in the Indian Ocean prior to and during the recent global warming hiatus (Dong & McPhaden, 2016) http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0130.1

Temperature and precipitation extremes in century-long gridded observations, reanalyses, and atmospheric model simulations (Donat et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025480/abstract

Atmospheric structure favoring high sea surface temperatures in the western equatorial Pacific (Wirasatriya et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025268/abstract

Spatial and temporal changes in daily temperature extremes in China during 1960–2011 (Shen et al. 2016) http://rd.springer.com/article/10.1007%2Fs00704-016-1934-3

Disaggregation of Remotely Sensed Land Surface Temperature: A New Dynamic Methodology (Zhan et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD024891/abstract

Impact of high-resolution sea surface temperature and urban data on estimations of surface air temperature in a regional climate (Adachi et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD024961/abstract

Trends of urban surface temperature and heat island characteristics in the Mediterranean (Benas et al. 2016) http://rd.springer.com/article/10.1007%2Fs00704-016-1905-8

Impacts of urbanization on summer climate in China: An assessment with coupled land-atmospheric modeling (Cao et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025210/abstract

The impact of climatic and non-climatic factors on land surface temperature in southwestern Romania (Roşca et al. 2016) http://rd.springer.com/article/10.1007%2Fs00704-016-1923-6

Posted in Climate claims, Climate science | Leave a Comment »

New research – climate sensitivity, forcings, and feedbacks (September 22, 2016)

Posted by Ari Jokimäki on September 22, 2016

Some of the latest papers on climate sensitivity, forcings, and feedbacks are shown below. First a few highlighted papers with abstracts and then a list of some other papers. If this subject interests you, be sure to check also the other papers – they are by no means less interesting than the highlighted ones.

Highlights

The Effects of Ocean Heat Uptake on Transient Climate Sensitivity (Rose & Rayborn, 2016) http://rd.springer.com/article/10.1007%2Fs40641-016-0048-4

Abstract: Transient climate sensitivity tends to increase on multiple timescales in climate models subject to an abrupt CO2 increase. The interdependence of radiative and ocean heat uptake processes governing this increase are reviewed. Heat uptake tends to be spatially localized to the subpolar oceans, and this pattern emerges rapidly from an initially uniform distribution. Global climatic impact of heat uptake is studied through the lens of the efficacy concept and a linear systems perspective in which responses to individual climate forcing agents are additive. Heat uptake can be treated as a slowly varying forcing on the atmosphere and surface, whose efficacy is strongly determined by its geographical pattern. An illustrative linear model driven by simple prescribed uptake patterns demonstrates the emergence of increasing climate sensitivity as a consequence of the slow decay of high-efficacy subpolar heat uptake. Evidence is reviewed for the key role of shortwave cloud feedbacks in setting the high efficacy of ocean heat uptake and thus in increasing climate sensitivity. A causal physical mechanism is proposed, linking subpolar heat uptake to a global-scale increase in lower-tropospheric stability. It is shown that the rate of increase in estimated inversion strength systematically slows as heat uptake decays. Variations in heat uptake should therefore manifest themselves as differences in low cloud feedbacks.

Understanding Climate Feedbacks and Sensitivity Using Observations of Earth’s Energy Budget (Loeb et al. 2016) http://rd.springer.com/article/10.1007%2Fs40641-016-0047-5

Abstract: While climate models and observations generally agree that climate feedbacks collectively amplify the surface temperature response to radiative forcing, the strength of the feedback estimates varies greatly, resulting in appreciable uncertainty in equilibrium climate sensitivity. Because climate feedbacks respond differently to different spatial variations in temperature, short-term observational records have thus far only provided a weak constraint for climate feedbacks operating under global warming. Further complicating matters is the likelihood of considerable time variation in the effective global climate feedback parameter under transient warming. There is a need to continue to revisit the underlying assumptions used in the traditional forcing-feedback framework, with an emphasis on how climate models and observations can best be utilized to reduce the uncertainties. Model simulations can also guide observational requirements and provide insight on how the observational record can most effectively be analyzed in order to make progress in this critical area of climate research.

Insights from a Refined Decomposition of Cloud Feedbacks (Zelinka et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL069917/abstract

Abstract: Decomposing cloud feedback into components due to changes in several gross cloud properties provides valuable insights into its physical causes. Here we present a refined decomposition that separately considers changes in free tropospheric and low cloud properties, better connecting feedbacks to individual governing processes and avoiding ambiguities present in a commonly used decomposition. It reveals that three net cloud feedback components are robustly nonzero: positive feedbacks from increasing free tropospheric cloud altitude and decreasing low cloud cover and a negative feedback from increasing low cloud optical depth. Low cloud amount feedback is the dominant contributor to spread in net cloud feedback but its anticorrelation with other components damps overall spread. The ensemble mean free tropospheric cloud altitude feedback is roughly 60% as large as the standard cloud altitude feedback because it avoids aliasing in low cloud reductions. Implications for the “null hypothesis” climate sensitivity from well-understood and robustly simulated feedbacks are discussed.

Rapid systematic assessment of the detection and attribution of regional anthropogenic climate change (Stone & Hansen, 2016) http://link.springer.com/article/10.1007%2Fs00382-015-2909-2

Abstract: Despite being a well-established research field, the detection and attribution of observed climate change to anthropogenic forcing is not yet provided as a climate service. One reason for this is the lack of a methodology for performing tailored detection and attribution assessments on a rapid time scale. Here we develop such an approach, based on the translation of quantitative analysis into the “confidence” language employed in recent Assessment Reports of the Intergovernmental Panel on Climate Change. While its systematic nature necessarily ignores some nuances examined in detailed expert assessments, the approach nevertheless goes beyond most detection and attribution studies in considering contributors to building confidence such as errors in observational data products arising from sparse monitoring networks. When compared against recent expert assessments, the results of this approach closely match those of the existing assessments. Where there are small discrepancies, these variously reflect ambiguities in the details of what is being assessed, reveal nuances or limitations of the expert assessments, or indicate limitations of the accuracy of the sort of systematic approach employed here. Deployment of the method on 116 regional assessments of recent temperature and precipitation changes indicates that existing rules of thumb concerning the detectability of climate change ignore the full range of sources of uncertainty, most particularly the importance of adequate observational monitoring.

One Year of Downwelling Spectral Radiance Measurements from 100 to 1400 cm−1 at Dome-Concordia: Results in Clear Conditions (Rizzi et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025341/abstract

Abstract: The present work examines downwelling radiance spectra measured at the ground during 2013 by a Far Infrared Fourier Transform Spectrometer at Dome-C, Antarctica. A tropospheric backscatter and depolarization Lidar is also deployed at same site and a radiosonde system is routinely operative. The measurements allow characterization of the water vapor and clouds infrared properties in Antarctica under all sky conditions. In this paper we specifically discuss cloud detection and the analysis in clear sky condition, required for the discussion of the results obtained in cloudy conditions. Firstly, the paper discusses the procedures adopted for the quality control of spectra acquired automatically. Then it describes the classification procedure used to discriminate spectra measured in clear-sky from cloudy conditions. Finally a selection is performed and 66 clear cases, spanning the whole year, are compared to simulations. The computation of layer molecular optical depth is performed with line-by-line techniques and a convolution to simulate the REFIR-PAD measurements; the downwelling radiance for selected clear cases is computed with a state-of-the-art adding-doubling code. The mean difference over all selected cases between simulated and measured radiance is within experimental error for all the selected micro-windows except for the negative residuals found for all micro-windows in the range 200 to 400 cm−1, with largest values around 295.1 cm−1. The paper discusses possible reasons for the discrepancy and identifies the incorrect magnitude of the water vapor total absorption coefficient as the cause of such large negative radiance bias below 400 cm−1.

Other papers

Dependence of global radiative feedbacks on evolving patterns of surface heat fluxes (Rugenstein et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL070907/abstract

Understanding the varied influence of mid-latitude jet position on clouds and cloud-radiative effects in observations and global climate models (Grise & Medeiros, 2016) http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0295.1

Effect of land cover change on snow free surface albedo across the continental United States (Wickham et al. 2016) http://www.sciencedirect.com/science/article/pii/S0921818116302892

Forced response and internal variability of summer climate over western North America (Kamae et al. 2016) http://rd.springer.com/article/10.1007%2Fs00382-016-3350-x

Detection and attribution of climate change at regional scale: case study of Karkheh river basin in the west of Iran (Zohrabi et al. 2016) http://rd.springer.com/article/10.1007%2Fs00704-016-1896-5

Atmospheric lifetimes, infrared absorption spectra, radiative forcings and global warming potentials of NF3 and CF3CF2Cl (CFC-115) (Totterdill et al. 2016) http://www.atmos-chem-phys.net/16/11451/2016/

A long-term study of aerosol–cloud interactions and their radiative effect at the Southern Great Plains using ground-based measurements (Sena et al. 2016) http://www.atmos-chem-phys.net/16/11301/2016/

Detection of dimming/brightening in Italy from homogenized all-sky and clear-sky surface solar radiation records and underlying causes (1959–2013) (Manara et al. 2016) http://www.atmos-chem-phys.net/16/11145/2016/

Effects of 20–100 nm particles on liquid clouds in the clean summertime Arctic (Leaitch et al. 2016) http://www.atmos-chem-phys.net/16/11107/2016/

Assessment of the first indirect radiative effect of ammonium-sulfate-nitrate aerosols in East Asia (Han et al. 2016) http://rd.springer.com/article/10.1007%2Fs00704-016-1913-8

Sensitivity of precipitation extremes to radiative forcing of greenhouse gases and aerosols (Lin et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL070869/abstract

Global climate forcing of aerosols embodied in international trade (Lin et al. 2016) http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2798.html

Reprocessing of HIRS Satellite Measurements from 1980-2015: Development Towards a Consistent Decadal Cloud Record (Menzel et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/JAMC-D-16-0129.1

Radiative Forcing from Anthropogenic Sulfur and Organic Emissions Reaching the Stratosphere (Yu et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL070153/abstract

Near miss: the importance of the natural atmospheric CO2 concentration to human historical evolution (Archer, 2016) http://rd.springer.com/article/10.1007%2Fs10584-016-1725-y

Long-Term Variations of Noctilucent Clouds at ALOMAR (Fiedler et al. 2016) http://www.sciencedirect.com/science/article/pii/S1364682616302024

Estimating Arctic sea-ice shortwave albedo from MODIS data (Qu et al. 2016) http://www.sciencedirect.com/science/article/pii/S0034425716303182

Surface albedo raise in the South American Chaco: Combined effects of deforestation and agricultural changes (Houspanossian et al. 2016) http://www.sciencedirect.com/science/article/pii/S0168192316303707

New Observational Evidence for a Positive Cloud Feedback that Amplifies the Atlantic Multidecadal Oscillation (Bellomo et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL069961/abstract

Surface water and heat exchange comparison between alpine meadow and bare land in a permafrost region of the Tibetan Plateau (You et al. 2016) http://www.sciencedirect.com/science/article/pii/S0168192316303598

foF2 vs Solar Indices for the Rome station: looking for the best general relation which is able to describe the anomalous minimum between cycles 23 and 24 (Perna & Pezzopane, 2016) http://www.sciencedirect.com/science/article/pii/S1364682616301894

Comparison of Methods: Attributing the 2014 record European temperatures to human influences (Uhe et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL069568/abstract

Relevance of long term time – series of atmospheric parameters at a mountain observatory to models for climate change (Kancírová et al. 2016) http://www.sciencedirect.com/science/article/pii/S1364682616301882

An energy balance perspective on regional CO2-induced temperature changes in CMIP5 models (Räisänen, 2016) http://rd.springer.com/article/10.1007%2Fs00382-016-3277-2

Posted in Climate claims, Climate science | Leave a Comment »

New research – temperature (September 5, 2016)

Posted by Ari Jokimäki on September 5, 2016

Some of the latest papers on temperature (in a climatic sense) are shown below. First a few highlighted papers with abstracts and then a list of some other papers. If this subject interests you, be sure to check also the other papers – they are by no means less interesting than the highlighted ones.

Highlights

Observed and simulated full-depth ocean heat-content changes for 1970–2005 (Cheng et al. 2016) http://www.ocean-sci.net/12/925/2016/

Abstract: Greenhouse-gas emissions have created a planetary energy imbalance that is primarily manifested by increasing ocean heat content (OHC). Updated observational estimates of full-depth OHC change since 1970 are presented that account for recent advancements in reducing observation errors and biases. The full-depth OHC has increased by 0.74 [0.68, 0.80]  ×  1022 J yr-1 (0.46 Wm−2) and 1.22 [1.16–1.29]  ×  1022 J yr-1 (0.75 Wm-2) for 1970–2005 and 1992–2005, respectively, with a 5 to 95 % confidence interval of the median. The CMIP5 models show large spread in OHC changes, suggesting that some models are not state-of-the-art and require further improvements. However, the ensemble median has excellent agreement with our observational estimate: 0.68 [0.54–0.82]  ×  1022 J yr-1 (0.42 Wm-2) from 1970 to 2005 and 1.25 [1.10–1.41]  ×  1022 J yr-1 (0.77 Wm-2) from 1992 to 2005. These results increase confidence in both the observational and model estimates to quantify and study changes in Earth’s energy imbalance over the historical period. We suggest that OHC be a fundamental metric for climate model validation and evaluation, especially for forced changes (decadal timescales).

Pacific sea level rise patterns and global surface temperature variability (Peyser et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL069401/abstract

Abstract: During 1998–2012, climate change and sea level rise (SLR) exhibit two notable features: a slowdown of global surface warming (hiatus) and a rapid SLR in the tropical western Pacific. To quantify their relationship, we analyze the long-term control simulations of 38 climate models. We find a significant and robust correlation between the east-west contrast of dynamic sea level (DSL) in the Pacific and global mean surface temperature (GST) variability on both interannual and decadal time scales. Based on linear regression of the multimodel ensemble mean, the anomalously fast SLR in the western tropical Pacific observed during 1998–2012 indicates suppression of a potential global surface warming of 0.16° ± 0.06°C. In contrast, the Pacific contributed 0.29° ± 0.10°C to the significant interannual GST increase in 1997/1998. The Pacific DSL anomalies observed in 2015 suggest that the strong El Niño in 2015/2016 could lead to a 0.21° ± 0.07°C GST jump.

Contrasting effects of urbanization and agriculture on surface temperature in eastern China (Zhou et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025359/abstract

Abstract: The combined effect of urbanization and agriculture, two most pervasive land use activities, on the surface climate remains poorly understood. Using Moderate Resolution Imaging Spectroradiometer data over 2010–2015 and forests as reference, we showed that urbanization warmed the land surface temperature (LST), especially during the daytime and in growing seasons (maximized at 5.0 ± 2.0°C in May), whereas agriculture (dominated by double-cropping system) cooled the LST in two growing seasons during the daytime and all the months but July during the nighttime in Jiangsu Province, eastern China. Collectively, they had insignificant effects on the LST during the day (−0.01°C) and cooled the LST by −0.6°C at night. We also found large geographic variations associated with their thermal effects, indicated by a warming tendency southward. These spatiotemporal patterns depend strongly on vegetation activity, evapotranspiration, surface albedo, and the background climate. Our results emphasize the great potential of agriculture in offsetting the heating effects caused by rapid urbanization in China.

A summer temperature bias in early alcohol thermometers (Camuffo & Valle, 2016) http://rd.springer.com/article/10.1007%2Fs10584-016-1760-8

Abstract: This paper analyses the response of alcohol thermometers in relation to the departure from linearity and the choice of the calibration points. The result is that alcohol thermometers are affected by large departures that reach a maximum (i.e. −6 °C) at 50 °C ambient temperature. This may have caused a severe bias in early records, when alcohol thermometers were popular, especially during the Little Ice Age. Choosing a lower temperature for the upper point, calibration may substantially reduce this bias. Examples are given with thermometers in use in the 17th and 18th centuries. A careful correction of long series is necessary to avoid misleading climate interpretations.

The phenology of Arctic Ocean Surface warming (Steele & Dickinson, 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JC012089/abstract

Abstract: In this work, we explore the seasonal relationships (i.e., the phenology) between sea ice retreat, sea surface temperature (SST), and atmospheric heat fluxes in the Pacific Sector of the Arctic Ocean, using satellite and reanalysis data. We find that where ice retreats early in most years, maximum summertime SSTs are usually warmer, relative to areas with later retreat. For any particular year, we find that anomalously early ice retreat generally leads to anomalously warm SSTs. However, this relationship is weak in the Chukchi Sea, where ocean advection plays a large role. It is also weak where retreat in a particular year happens earlier than usual, but still relatively late in the season, primarily because atmospheric heat fluxes are weak at that time. This result helps to explain the very different ocean warming responses found in two recent years with extreme ice retreat, 2007 and 2012. We also find that the timing of ice retreat impacts the date of maximum SST, owing to a change in the ocean surface buoyancy and momentum forcing that occurs in early August that we term the Late Summer Transition (LST). After the LST, enhanced mixing of the upper ocean leads to cooling of the ocean surface even while atmospheric heat fluxes are still weakly downward. Our results indicate that in the near-term, earlier ice retreat is likely to cause enhanced ocean surface warming in much of the Arctic Ocean, although not where ice retreat still occurs late in the season.

Other papers

Comparisons of time series of annual mean surface air temperature for China since the 1900s: Observations, model simulations and extended reanalysis (Li et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-16-0092.1

First ground-based observations of mesopause temperatures above the Eastern-Mediterranean Part I: Multi-day oscillations and tides (Silber et al. 2016) http://www.sciencedirect.com/science/article/pii/S1364682616302206

An enhanced single-channel algorithm for retrieving land surface temperature from Landsat series data (Wang et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025270/abstract

Observed changes of temperature extremes in Serbia over the period 1961 − 2010 (Ruml et al. 2016) http://www.sciencedirect.com/science/article/pii/S016980951630254X

The inter-annual variations and the long-term trends of monthly air temperatures in Iraq over the period 1941–2013 (Muslih & Błażejczyk, 2016) http://rd.springer.com/article/10.1007%2Fs00704-016-1915-6

A multiregion model evaluation and attribution study of historical changes in the area affected by temperature and precipitation extremes (Dittus et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0164.1

Changes in wind speed under heat waves enhance urban heat islands in Beijing metropolitan area (Li et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/JAMC-D-16-0102.1

Regional differential behaviour of maximum temperatures in the Iberian Peninsula regarding the Summer NAO in the second half of the twentieth century (Favà et al. 2016) http://www.sciencedirect.com/science/article/pii/S0169809516302319

Confidence intervals for time averages in the presence of long range correlations, a case study on earth surface temperature anomalies (Massah & Kantz, 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL069555/abstract

An ensemble of ocean reanalyses for 1815–2013 with sparse observational input (Giese et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JC012079/abstract

Arctic-North Pacific coupled impacts on the late autumn cold in North America (Sung et al. 2016) http://iopscience.iop.org/article/10.1088/1748-9326/11/8/084016/meta

Wet-bulb, dew point, and air temperature trends in Spain (Moratiel et al. 2016) http://rd.springer.com/article/10.1007%2Fs00704-016-1891-x

Insights into elevation-dependent warming in the Tibetan Plateau-Himalayas from CMIP5 model simulations (Palazzi et al. 2016) http://rd.springer.com/article/10.1007%2Fs00382-016-3316-z

Spatial variations in temperature in a mountainous region of Jeju Island, South Korea (Um & Kim, 2016) http://onlinelibrary.wiley.com/doi/10.1002/joc.4854/abstract

Gap filling and homogenization of climatological datasets in the headwater region of the Upper Blue Nile Basin, Ethiopia (Woldesenbet et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/joc.4839/abstract

A homogenized long-term temperature record for the Western Cape Province in South Africa: 1916–2013 (Lakhraj-Govender et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/joc.4849/abstract

Inter-model diversity of Arctic amplification caused by global warming and its relationship with the Inter-tropical Convergence Zone in CMIP5 climate models (Yim et al. 2016) http://link.springer.com/article/10.1007%2Fs00382-016-3303-4

Urban–rural differences in near-surface air temperature as resolved by the Central Europe Refined analysis (CER): sensitivity to planetary boundary layer schemes and urban canopy models (Jänicke et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/joc.4835/abstract

Monotonic Decrease of the Zonal SST Gradient of the Equatorial Pacific as a Function of CO2 Concentration in CCSM3 and CCSM4 (Yang et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025231/abstract

Recent seasonal and long-term changes in southern Australian frost occurrence (Crimp et al. 2016) http://rd.springer.com/article/10.1007%2Fs10584-016-1763-5

Surface temperature trends from homogenized time series in South Africa: 1931–2015 (Kruger & Nxumalo, 2016) http://onlinelibrary.wiley.com/doi/10.1002/joc.4851/abstract

Investigations of the middle atmospheric thermal structure and oscillations over sub-tropical regions in the Northern and Southern Hemispheres (Sharma et al. 2016) http://rd.springer.com/article/10.1007%2Fs00382-016-3293-2

Recent amplification of the North American winter temperature dipole (Singh et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025116/abstract

Use of remotely-sensed land surface temperature as a proxy for air temperatures at high elevations: Findings from a 5000 metre elevational transect across Kilimanjaro (Pepin et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025497/abstract

Spatial distribution of temperature trends and extremes over Maharashtra and Karnataka States of India (Dhorde et al. 2016) http://rd.springer.com/article/10.1007%2Fs00704-016-1876-9

Assessing atmospheric temperature data sets for climate studies (Cederlöf et al. 2016) http://www.tellusa.net/index.php/tellusa/article/view/31503

Ocean heat uptake and interbasin transport of passive and redistributive surface heating (Garuba & Klinger, 2016) http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0138.1

Temperature and precipitation regional climate series over the central Pyrenees during 1910–2013 (Pérez-Zanón et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/joc.4823/abstract

Posted in Climate claims, Climate science | Leave a Comment »

New research – climate models and projections (August 16, 2016)

Posted by Ari Jokimäki on August 16, 2016

Some of the latest papers on climate models and projections are shown below. First a few highlighted papers with abstracts and then a list of some other papers. If this subject interests you, be sure to check also the other papers – they are by no means less interesting than the highlighted ones.

Highlights

CMIP5 scientific gaps and recommendations for CMIP6 (Stouffer et al. 2016)http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-15-00013.1

Abstract: The Coupled Model Intercomparison Project (CMIP) is an ongoing coordinated international activity of numerical experimentation of unprecedented scope and impact on climate science. Its most recent fifth phase, CMIP5, has created nearly two petabytes of output from dozens of experiments performed by dozens of comprehensive climate models available to the climate science research community. In so doing, it has greatly advanced climate science. While CMIP5 has given answers to important science questions, with the help of a community survey we identify and motivate three broad topics here that guided the scientific framework of the next phase of CMIP, i.e. CMIP6:

1.How does the Earth System respond to changes in forcing?

2.What are the origins and consequences of systematic model biases?

3.How can we assess future climate changes given internal climate variability, predictability and uncertainties in scenarios?

CMIP has demonstrated the power of idealized experiments to better understand how the climate system works. We expect that these idealized approaches will continue to contribute to CMIP6. The quantification of radiative forcings and responses was poor and requires new methods and experiments to address this gap. There are a number of systematic model biases that appear in all phases of CMIP which remain a major climate modeling challenge. These biases need increased attention to better understand their origins and consequences through targeted experiments. Improving understanding of the mechanisms underlying internal climate variability for more skillful decadal climate predictions and long-term projections remains another challenge for CMIP6.

Climate change in the next 30 years: What can a convection-permitting model tell us that we did not already know? (Fosser et al. 2016) http://rd.springer.com/article/10.1007%2Fs00382-016-3186-4

Abstract: To investigate the climate change in the next 30 years over a complex terrain in southwestern Germany, simulations performed with the regional climate model COSMO-CLM at convection-permitting resolution are compared to simulations at 7 km resolution with parameterised convection. An earlier study has shown the main benefits of convection-permitting resolution in the hourly statistics and the diurnal cycle of precipitation intensities. Here, we investigate whether the improved simulation of precipitation in the convection-permitting model is affecting future climate projections in summer. Overall, the future scenario (ECHAM5 with A1B forcing) brings weak changes in mean precipitation, but stronger hourly intensities in the morning and less frequent but more intense daily precipitation. The two model simulations produce similar changes in climate, despite differences in their physical characteristics linked to the formation of convective precipitation. A significant increase in the morning precipitation probably due to large-scale forced convection is found when considering only the most extreme events (above 50 mm/day). In this case, even the diurnal cycles of precipitation and convection-related indices are similar between resolutions, leading to the conclusion that the 7 km model sufficiently resolves the most extreme convective events. In this region and time periods, the 7 km resolution is deemed sufficient for most assessments of near future precipitation change. However, conclusions could be dependent on the characteristics of the region of investigation.

Evaluating Arctic warming mechanisms in CMIP5 models (Franzke et al. 2016) http://link.springer.com/article/10.1007%2Fs00382-016-3262-9

Abstract: Arctic warming is one of the most striking signals of global warming. The Arctic is one of the fastest warming regions on Earth and constitutes, thus, a good test bed to evaluate the ability of climate models to reproduce the physics and dynamics involved in Arctic warming. Different physical and dynamical mechanisms have been proposed to explain Arctic amplification. These mechanisms include the surface albedo feedback and poleward sensible and latent heat transport processes. During the winter season when Arctic amplification is most pronounced, the first mechanism relies on an enhancement in upward surface heat flux, while the second mechanism does not. In these mechanisms, it has been proposed that downward infrared radiation (IR) plays a role to a varying degree. Here, we show that the current generation of CMIP5 climate models all reproduce Arctic warming and there are high pattern correlations—typically greater than 0.9—between the surface air temperature (SAT) trend and the downward IR trend. However, we find that there are two groups of CMIP5 models: one with small pattern correlations between the Arctic SAT trend and the surface vertical heat flux trend (Group 1), and the other with large correlations (Group 2) between the same two variables. The Group 1 models exhibit higher pattern correlations between Arctic SAT and 500 hPa geopotential height trends, than do the Group 2 models. These findings suggest that Arctic warming in Group 1 models is more closely related to changes in the large-scale atmospheric circulation, whereas in Group 2, the albedo feedback effect plays a more important role. Interestingly, while Group 1 models have a warm or weak bias in their Arctic SAT, Group 2 models show large cold biases. This stark difference in model bias leads us to hypothesize that for a given model, the dominant Arctic warming mechanism and trend may be dependent on the bias of the model mean state.

The Impact of SST Biases on Projections of Anthropogenic Climate Change: A Greater Role for Atmosphere-only Models? (He & Soden, 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL069803/abstract

Abstract: There is large uncertainty in the model simulation of regional climate change from anthropogenic forcing. Recent studies have tried to link such uncertainty to intermodel differences in the pattern of sea surface temperature (SST) change. On the other hand, coupled climate models also contain systematic biases in their climatology, largely due to drift in SSTs. To the extent that the projected changes depend on the mean state, biases in the present-day climatology also contribute to the intermodel spread in climate change projections. By comparing atmospheric general circulation model (AGCM) simulations using the climatological SSTs from different coupled models, we show that biases in the climatological SST generally have a larger impact on regional projections over land than do intermodel differences in the pattern of SST change. These results advocate for a greater application of AGCM simulations with observed SSTs or flux-adjusted coupled models to improve regional projections of anthropogenic climate change.

The art and science of climate model tuning (Hourdin et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-15-00135.1

Abstract: We survey the rationale and diversity of approaches for tuning, a fundamental aspect of climate modeling which should be more systematically documented and taken into account in multi-model analysis.

The process of parameter estimation targeting a chosen set of observations is an essential aspect of numerical modeling. This process is usually named tuning in the climate modeling community. In climate models, the variety and complexity of physical processes involved, and their interplay through a wide range of spatial and temporal scales, must be summarized in a series of approximate sub-models. Most sub-models depend on uncertain parameters. Tuning consists of adjusting the values of these parameters to bring the solution as a whole into line with aspects of the observed climate. Tuning is an essential aspect of climate modeling with its own scientific issues, which is probably not advertised enough outside the community of model developers. Optimization of climate models raises important questions about whether tuning methods a priori constrain the model results in unintended ways that would affect our confidence in climate projections. Here we present the definition and rationale behind model tuning, review specific methodological aspects, and survey the diversity of tuning approaches used in current climate models. We also discuss the challenges and opportunities in applying so-called ‘objective‘ methods in climate model tuning. We discuss how tuning methodologies may affect fundamental results of climate models, such as climate sensitivity. The article concludes with a series of recommendations to make the process of climate model tuning more transparent.

Other papers

High-resolution ensemble projections of near-term regional climate over the continental United States (Ashfaq et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025285/abstract

Twentieth century temperature trends in CMIP3, CMIP5, and CESM-LE climate simulations – spatial-temporal uncertainties, differences and their potential sources (Kumar et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2015JD024382/abstract

Assessing the robustness and uncertainties of projected changes in temperature and precipitation in AR4 Global Climate Models over the Arabian Peninsula (Almazroui et al. 2016) http://www.sciencedirect.com/science/article/pii/S0169809516302058

The influence of model resolution on temperature variability (Klavans et al. 2016) http://link.springer.com/article/10.1007%2Fs00382-016-3249-6

Evaluation of the skill of North-American Multi-Model Ensemble (NMME) Global Climate Models in predicting average and extreme precipitation and temperature over the continental USA (Slater et al. 2016) http://link.springer.com/article/10.1007%2Fs00382-016-3286-1

Assessing uncertainties in land cover projections (Alexander et al. 2016) http://onlinelibrary.wiley.com/doi/10.1111/gcb.13447/abstract

Effects of southeastern Pacific sea surface temperature on the double-ITCZ bias in NCAR CESM1 (Song & Zhang, 2016) http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-15-0852.1

Stochastic Parameterization: Towards a new view of Weather and Climate Models (Berner et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-15-00268.1

Do convection-permitting regional climate models improve projections of future precipitation change? (Kendon et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-15-0004.1

MiKlip – a National Research Project on Decadal Climate Prediction (Marotzke et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-15-00184.1

Posted in Climate claims, Climate science | 1 Comment »

New research – composition of atmosphere (August 15, 2016)

Posted by Ari Jokimäki on August 15, 2016

Some of the latest papers on composition of atmosphere are shown below. First a few highlighted papers with abstracts and then a list of some other papers. If this subject interests you, be sure to check also the other papers – they are by no means less interesting than the highlighted ones.

Highlights

Role of OH variability in the stalling of the global atmospheric CH4 growth rate from 1999 to 2006 (McNorton et al. 2016) http://www.atmos-chem-phys.net/16/7943/2016/

Abstract: The growth in atmospheric methane (CH4) concentrations over the past 2 decades has shown large variability on a timescale of several years. Prior to 1999 the globally averaged CH4 concentration was increasing at a rate of 6.0 ppb yr−1, but during a stagnation period from 1999 to 2006 this growth rate slowed to 0.6 ppb yr−1. From 2007 to 2009 the growth rate again increased to 4.9 ppb yr−1. These changes in growth rate are usually ascribed to variations in CH4 emissions. We have used a 3-D global chemical transport model, driven by meteorological reanalyses and variations in global mean hydroxyl (OH) concentrations derived from CH3CCl3 observations from two independent networks, to investigate these CH4 growth variations. The model shows that between 1999 and 2006 changes in the CH4 atmospheric loss contributed significantly to the suppression in global CH4 concentrations relative to the pre-1999 trend. The largest factor in this is relatively small variations in global mean OH on a timescale of a few years, with minor contributions of atmospheric transport of CH4 to its sink region and of atmospheric temperature. Although changes in emissions may be important during the stagnation period, these results imply a smaller variation is required to explain the observed CH4 trends. The contribution of OH variations to the renewed CH4 growth after 2007 cannot be determined with data currently available.

Diverse policy implications for future ozone and surface UV in a changing climate (Butler et al. 2016) http://iopscience.iop.org/article/10.1088/1748-9326/11/6/064017/meta

Abstract: Due to the success of the Montreal Protocol in limiting emissions of ozone-depleting substances, concentrations of atmospheric carbon dioxide, nitrous oxide, and methane will control the evolution of total column and stratospheric ozone by the latter half of the 21st century. As the world proceeds down the path of reducing climate forcing set forth by the 2015 Conference of the Parties to the United Nations Framework Convention on Climate Change (COP 21), a broad range of ozone changes are possible depending on future policies enacted. While decreases in tropical stratospheric ozone will likely persist regardless of the future emissions scenario, extratropical ozone could either remain weakly depleted or even increase well above historical levels, with diverse implication for ultraviolet (UV) radiation. The ozone layer’s dependence on future emissions of these gases creates a complex policy decision space for protecting humans and ecosystems, which includes unexpected options such as accepting nitrous oxide emissions in order to maintain historical column ozone and surface UV levels.

Changes in surface aerosol extinction trends over China during 1980–2013 inferred from quality-controlled visibility data (Li et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL070201/abstract

Abstract: Pollution in China has been attracting extensive attention both globally and regionally, especially due to the perceptually worsening “smog” condition in recent years. We use routine visibility measurements from 1980 to 2013 at 272 WMO stations in China to assess the temporal changes in the magnitude and the sign of pollution trends. A strict and comprehensive quality control procedure is enforced by considering several issues not typically addressed in previous studies. Two methods are used to independently estimate the trend and its significance level. Results show that in general, a strong increase in Aerosol Extinction Coefficient (AEC) over the majority of China is observed in the 1980s, followed by a moderate decrease in the 1990s, another increase in the 2000s, and a shift to decrease since around 2006 for some regions. Seasonally, winter and fall trends appear to be the strongest, while summer has the lowest trend.

The millennium water vapour drop in chemistry–climate model simulations (Brinkop et al. 2016) http://www.atmos-chem-phys.net/16/8125/2016/

Abstract: This study investigates the abrupt and severe water vapour decline in the stratosphere beginning in the year 2000 (the “millennium water vapour drop”) and other similarly strong stratospheric water vapour reductions by means of various simulations with the state-of-the-art Chemistry-Climate Model (CCM) EMAC (ECHAM/MESSy Atmospheric Chemistry Model). The model simulations differ with respect to the prescribed sea surface temperatures (SSTs) and whether nudging is applied or not. The CCM EMAC is able to most closely reproduce the signature and pattern of the water vapour drop in agreement with those derived from satellite observations if the model is nudged. Model results confirm that this extraordinary water vapour decline is particularly obvious in the tropical lower stratosphere and is related to a large decrease in cold point temperature. The drop signal propagates under dilution to the higher stratosphere and to the poles via the Brewer–Dobson circulation (BDC). We found that the driving forces for this significant decline in water vapour mixing ratios are tropical sea surface temperature (SST) changes due to a coincidence with a preceding strong El Niño–Southern Oscillation event (1997/1998) followed by a strong La Niña event (1999/2000) and supported by the change of the westerly to the easterly phase of the equatorial stratospheric quasi-biennial oscillation (QBO) in 2000. Correct (observed) SSTs are important for triggering the strong decline in water vapour. There are indications that, at least partly, SSTs contribute to the long period of low water vapour values from 2001 to 2006. For this period, the specific dynamical state of the atmosphere (overall atmospheric large-scale wind and temperature distribution) is important as well, as it causes the observed persistent low cold point temperatures. These are induced by a period of increased upwelling, which, however, has no corresponding pronounced signature in SSTs anomalies in the tropics. Our free-running simulations do not capture the drop as observed, because a) the cold point temperature has a low bias and thus the water vapour variability is reduced and b) because they do not simulate the appropriate dynamical state. Large negative water vapour declines are also found in other years and seem to be a feature which can be found after strong combined El Niño/La Niña events if the QBO west phase during La Niña changes to the east phase.

Evaluation of 4 years of continuous δ13C(CO2) data using a moving Keeling plot method (Vardag, Hammer & Levin, 2016)
http://www.biogeosciences.net/13/4237/2016/

Abstract: Different carbon dioxide (CO2) emitters can be distinguished by their carbon isotope ratios. Therefore measurements of atmospheric δ13C(CO2) and CO2 concentration contain information on the CO2 source mix in the catchment area of an atmospheric measurement site. This information may be illustratively presented as the mean isotopic source signature. Recently an increasing number of continuous measurements of δ13C(CO2) and CO2 have become available, opening the door to the quantification of CO2 shares from different sources at high temporal resolution. Here, we present a method to compute the CO2 source signature (δS) continuously and evaluate our result using model data from the Stochastic Time-Inverted Lagrangian Transport model. Only when we restrict the analysis to situations which fulfill the basic assumptions of the Keeling plot method does our approach provide correct results with minimal biases in δS. On average, this bias is 0.2 ‰ with an interquartile range of about 1.2 ‰ for hourly model data. As a consequence of applying the required strict filter criteria, 85 % of the data points – mainly daytime values – need to be discarded. Applying the method to a 4-year dataset of CO2 and δ13C(CO2) measured in Heidelberg, Germany, yields a distinct seasonal cycle of δS. Disentangling this seasonal source signature into shares of source components is, however, only possible if the isotopic end members of these sources – i.e., the biosphere, δbio, and the fuel mix, δF – are known. From the mean source signature record in 2012, δbio could be reliably estimated only for summer to (−25.0 ± 1.0) ‰ and δF only for winter to (−32.5 ± 2.5) ‰. As the isotopic end members δbio and δF were shown to change over the season, no year-round estimation of the fossil fuel or biosphere share is possible from the measured mean source signature record without additional information from emission inventories or other tracer measurements.

Other papers

Intercomparison of in situ NDIR and column FTIR measurements of CO2 at Jungfraujoch (Schibig et al. 2016) http://www.atmos-chem-phys.net/16/9935/2016/

Evaluation of 4 years of continuous δ13C(CO2) data using a moving Keeling plot method (Vardag, Hammer & Levin, 2016) http://www.biogeosciences.net/13/4237/2016/

Intra-seasonal variability of atmospheric CO2 concentrations over India during summer monsoons (Kumar et al. 2016) http://www.sciencedirect.com/science/article/pii/S1352231016305428

Impact of ENSO on variability of AIRS retrieved CO2 over India (Kumar et al. 2016) http://www.sciencedirect.com/science/article/pii/S1352231016305209

Large XCH4 anomaly in summer 2013 over northeast Asia observed by GOSAT (Ishizawa et al. 2016) http://www.atmos-chem-phys.net/16/9149/2016/

Can we detect regional methane anomalies? A comparison between three observing systems (Cressot et al. 2016) http://www.atmos-chem-phys.net/16/9089/2016/

Non-homogeneous vertical distribution of methane over Indian region using surface, aircraft and satellite based data (Kavitha & Nair, 2016) http://www.sciencedirect.com/science/article/pii/S1352231016305015

A probabilistic study of the return of stratospheric ozone to 1960 levels (Södergren et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016GL069700/abstract

The representation of solar cycle signals in stratospheric ozone – Part 1: A comparison of recently updated satellite observations (Maycock et al. 2016) http://www.atmos-chem-phys.net/16/10021/2016/

Summer ozone concentrations in the vicinity of the Great Salt Lake (Horel et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/asl.680/abstract

Impact of emissions and +2 °C climate change upon future ozone and nitrogen dioxide over Europe (Watson et al. 2016) http://www.sciencedirect.com/science/article/pii/S1352231016305714

Natural and Anthropogenic Aerosol Trends from Satellite and Surface Observations and Model Simulations over the North Atlantic Ocean from 2002 to 2012 (Jongeward et al. 2016) http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-15-0308.1

Aerosol Lidar Observations of Atmospheric Mixing in Los Angeles: Climatology and Implications for Greenhouse Gas Observations (Ware et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD024953/abstract

Future aerosol emissions: a multi-model comparison (Smith et al. 2016) http://rd.springer.com/article/10.1007%2Fs10584-016-1733-y

Multi-Year Study of the Dependence of Sea Salt Aerosol on Wind Speed and Sea Ice Conditions in the Coastal Arctic (May et al. 2016) http://onlinelibrary.wiley.com/doi/10.1002/2016JD025273/abstract

Effects of climate changes on dust aerosol over East Asia from RegCM3 (Zhang et al. 2016) http://www.sciencedirect.com/science/article/pii/S1674927816300053

Posted in Climate claims, Climate science | Leave a Comment »

 
%d bloggers like this: