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Archive for December, 2012

New research from last week 52/2012

Posted by Ari Jokimäki on December 31, 2012

Here it is – the last post in the New research from last week series. I thank all researchers for providing continuous stream of interesting science to include to weekly batches. I also thank all readers for their interest in the series. New research reporting will continue in some form, which is currently uncertain. I probably will continue pointing out some interesting papers in my Twitter feed, but I expect that even there will be a quiet period in coming weeks. Happy new year for all climate science fans everywhere!

RegFeedback


Time-varying climate sensitivity from regional feedbacks

Time-varying climate sensitivity from regional feedbacks – Armour et al. (2012) [FULL TEXT]

Abstract: “The sensitivity of global climate with respect to forcing is generally described in terms of the global climate feedback—the global radiative response per degree of global annual mean surface temperature change. While the global climate feedback is often assumed to be constant, its value—diagnosed from global climate models—shows substantial time-variation under transient warming. Here we propose that a reformulation of the global climate feedback in terms of its contributions from regional climate feedbacks provides a clear physical insight into this behavior. Using (i) a state-of-the-art global climate model and (ii) a low-order energy balance model, we show that the global climate feedback is fundamentally linked to the geographic pattern of regional climate feedbacks and the geographic pattern of surface warming at any given time. Time-variation of the global climate feedback arises naturally when the pattern of surface warming evolves, actuating regional feedbacks of different strengths. This result has substantial implications for our ability to constrain future climate changes from observations of past and present climate states. The regional climate feedbacks formulation reveals fundamental biases in a widely-used method for diagnosing climate sensitivity, feedbacks and radiative forcing—the regression of the global top-of-atmosphere radiation flux on global surface temperature. Further, it suggests a clear mechanism for the ‘efficacies’ of both ocean heat uptake and radiative forcing.”

Citation: Kyle C. Armour, Cecilia M. Bitz, Gerard H. Roe, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00544.1.


West Antarctic rapid glacier retreat may be exceptional during the Holocene

Grounding-line retreat of the West Antarctic Ice Sheet from inner Pine Island Bay – Hillenbrand et al. (2012)

Abstract: “Ice loss from the marine-based, potentially unstable West Antarctic Ice Sheet (WAIS) contributes to current sea-level rise and may raise sea level by ≤3.3 m or even ≤5 m in the future. Over the past few decades, glaciers draining the WAIS into the Amundsen Sea Embayment (ASE) have shown accelerated ice flow, rapid thinning, and fast retreat of the grounding line (GL). However, the long-term context of this ice loss is poorly constrained, limiting our ability to accurately predict future WAIS behavior. Here we present a new chronology for WAIS retreat from the inner continental shelf of the eastern ASE, based on radiocarbon dates from three marine sediment cores. The ages document a retreat of the GL to within ∼100 km of its modern position before ca. 10,000 calibrated (cal.) yr B.P. This early deglaciation is consistent with ages for GL retreat from the western ASE. Our new data demonstrate that, in contrast to the Ross Sea, WAIS retreat from the ASE shelf was largely complete by the start of the Holocene. Our results further suggest either slow GL retreat from the inner ASE shelf throughout the Holocene, or that any episodes of fast GL retreat must have been short-lived. Thus, today’s rapid retreat may be exceptional during the Holocene and may originate in recent changes in regional climate, ocean circulation, or ice-sheet dynamics.”

Citation: Claus-Dieter Hillenbrand, Gerhard Kuhn, James A. Smith, Karsten Gohl, Alastair G.C. Graham, Robert D. Larter, Johann P. Klages, Rachel Downey, Steven G. Moreton, Matthias Forwick and David G. Vaughan, Geology, v. 41 no. 1 p. 35-38, doi: 10.1130/G33469.1.


Late Pleistocene tropical Pacific temperatures suggest higher climate sensitivity than currently thought

Late Pleistocene tropical Pacific temperature sensitivity to radiative greenhouse gas forcing – Dyez & Ravelo (2012)

Abstract: “Understanding how global temperature changes with increasing atmospheric greenhouse gas concentrations, or climate sensitivity, is of central importance to climate change research. Climate models provide sensitivity estimates that may not fully incorporate slow, long-term feedbacks such as those involving ice sheets and vegetation. Geological studies, on the other hand, can provide estimates that integrate long- and short-term climate feedbacks to radiative forcing. Because high latitudes are thought to be most sensitive to greenhouse gas forcing owing to, for example, ice-albedo feedbacks, we focus on the tropical Pacific Ocean to derive a minimum value for long-term climate sensitivity. Using Mg/Ca paleothermometry from the planktonic foraminifera Globigerinoides ruber from the past 500 k.y. at Ocean Drilling Program (ODP) Site 871 in the western Pacific warm pool, we estimate the tropical Pacific climate sensitivity parameter (λ) to be 0.94–1.06 °C (W m−2)−1, higher than that predicted by model simulations of the Last Glacial Maximum or by models of doubled greenhouse gas concentration forcing. This result suggests that models may not yet adequately represent the long-term feedbacks related to ocean circulation, vegetation and associated dust, or the cryosphere, and/or may underestimate the effects of tropical clouds or other short-term feedback processes.”

Citation: Kelsey A. Dyez and A. Christina Ravelo, Geology, v. 41 no. 1 p. 23-26, doi: 10.1130/G33425.1.


Dynamics played a major role for the Arctic ozone deficit in 2011

Attribution of the Arctic ozone column deficit in March 2011 – Isaksen et al. (2012)

Highlights: •Good model agreement with observations; •The model reproduces the Arctic ozone deficit in 2011; •Dynamics play a major role for the ozone deficit in 2011.

Abstract: “Arctic column ozone reached record low values (∼310 DU) during March of 2011, exposing Arctic ecosystems to enhanced UV-B. We identify the cause of this anomaly using the Oslo CTM2 atmospheric chemistry model driven by ECMWF meteorology to simulate Arctic ozone from 1998 through 2011. CTM2 successfully reproduces the variability in column ozone, from week to week, and from year to year, correctly identifying 2011 as an extreme anomaly over the period. By comparing parallel model simulations, one with all Arctic ozone chemistry turned off on January 1, we find that chemical ozone loss in 2011 is enhanced relative to previous years, but it accounted for only 23% of the anomaly. Weakened transport of ozone from middle latitudes, concurrent with an anomalously strong polar vortex, was the primary cause of the low ozone When the zonal winds relaxed in mid-March 2011, Arctic column ozone quickly recovered.”

Citation: Isaksen, I. S. A., et al. (2012), Attribution of the Arctic ozone column deficit in March 2011, Geophys. Res. Lett., 39, L24810, doi:10.1029/2012GL053876.


Accelerated loss of alpine glaciers in the Kodar Mountains of SE Siberia

Accelerated loss of alpine glaciers in the Kodar Mountains, south-eastern Siberia – Stokes et al. (2012)

Highlights: ► First ever multi-year study of glacier change from the Kodar Mountains, SE Siberia ► Small decline in glacier area from the 1960s to 1995 followed by dramatic reduction ► Reduction coincides with a marked summer warming trend that began in the 1980s ► Topography and supra-glacial debris cover modulate glacier response ► These glaciers may transition into a type of rock glacier within a few decades.

Abstract: “The recession of mountain glaciers around the world has been linked to anthropogenic climate change and small glaciers (e.g. < 2 km2) are thought to be particularly vulnerable, with reports of their disappearance from several regions. However, the response of small glaciers to climate change can be modulated by non-climatic factors such as topography and debris cover and there remain a number of regions where their recent change has evaded scrutiny. This paper presents results of the first multi-year remote sensing survey of glaciers in the Kodar Mountains, the only glaciers in SE Siberia, which we compare to previous glacier inventories from this continental setting that reported total glacier areas of 18.8 km2 in ca. 1963 (12.6 km2 of exposed ice) and 15.5 km2 in 1974 (12 km2 of exposed ice). Mapping their debris-covered termini is difficult but delineation of debris-free ice on Landsat imagery reveals 34 glaciers with a total area of 11.72 ± 0.72 km2 in 1995, followed by a reduction to 9.53 ± 0.29 km2 in 2001 and 7.01 ± 0.23 km2 in 2010. This represents a ~ 44% decrease in exposed glacier ice between ca. 1963 and 2010, but with 40% lost since 1995 and with individual glaciers losing as much as 93% of their exposed ice. Thus, although continental glaciers are generally thought to be less sensitive than their maritime counterparts, a recent acceleration in shrinkage of exposed ice has taken place and we note its coincidence with a strong summer warming trend in the region initiated at the start of the 1980s. Whilst smaller and shorter glaciers have, proportionally, tended to shrink more rapidly, we find no statistically significant relationship between shrinkage and elevation characteristics, aspect or solar radiation. This is probably due to the small sample size, limited elevation range, and topographic setting of the glaciers in deep valleys-heads. Furthermore, many of the glaciers possess debris-covered termini and it is likely that the ablation of buried ice is lagging the shrinkage of exposed ice, such that a growth in the proportion of debris cover is occurring, as observed elsewhere. If recent trends continue, we hypothesise that glaciers could evolve into a type of rock glacier within the next few decades, introducing additional complexity in their response and delaying their potential demise.”

Citation: Chris R. Stokes, Maria Shahgedanova, Ian S. Evans, Victor V. Popovnin, Global and Planetary Change, http://dx.doi.org/10.1016/j.gloplacha.2012.12.010.


Central West Antarctica among the most rapidly warming regions on Earth

Central West Antarctica among the most rapidly warming regions on Earth – Bromwich et al. (2012)

Abstract: “There is clear evidence that the West Antarctic Ice Sheet is contributing to sea-level rise. In contrast, West Antarctic temperature changes in recent decades remain uncertain. West Antarctica has probably warmed since the 1950s, but there is disagreement regarding the magnitude, seasonality and spatial extent of this warming. This is primarily because long-term near-surface temperature observations are restricted to Byrd Station in central West Antarctica, a data set with substantial gaps. Here, we present a complete temperature record for Byrd Station, in which observations have been corrected, and gaps have been filled using global reanalysis data and spatial interpolation. The record reveals a linear increase in annual temperature between 1958 and 2010 by 2.4±1.2 °C, establishing central West Antarctica as one of the fastest-warming regions globally. We confirm previous reports of West Antarctic warming, in annual average and in austral spring and winter, but find substantially larger temperature increases. In contrast to previous studies, we report statistically significant warming during austral summer, particularly in December–January, the peak of the melting season. A continued rise in summer temperatures could lead to more frequent and extensive episodes of surface melting of the West Antarctic Ice Sheet. These results argue for a robust long-term meteorological observation network in the region.”

Citation: David H. Bromwich, Julien P. Nicolas, Andrew J. Monaghan, Matthew A. Lazzara, Linda M. Keller, George A. Weidner & Aaron B. Wilson, Nature Geoscience, 2012, doi:10.1038/ngeo1671.


Other studies from last week

Rainfall variations in south-eastern Australia part 1: consolidating evidence from pre-instrumental documentary sources, 1788–1860 – Fenby & Gergis (2012)

Rainfall variations in south-eastern Australia part 2: a comparison of documentary, early instrumental and palaeoclimate records, 1788–2008 – Gergis & Ashcroft (2012)

Impact of anthropogenic absorbing aerosols on clouds and precipitation: A review of recent progresses – Wang (2012)

Impact of late Holocene climate variability and anthropogenic activities on Biscayne Bay (Florida, U.S.A.): Evidence from diatoms – Wachnicka et al. (2012)

Feedbacks in emission-driven and concentration-driven global carbon budgets – Boer & Arora (2012)

Changes in Arctic sea ice result in increasing light transmittance and absorption – Nicolaus et al. (2012)

A global analysis of soil microbial biomass carbon, nitrogen and phosphorus in terrestrial ecosystems – Xu et al. (2012)

Epifauna dynamics at an offshore foundation – implications of future wind power farming in the North Sea – Krone et al. (2012)

Effects of two decades of rising sea surface temperatures on sublittoral macrobenthos communities in Northern Ireland, UK – Goodwin et al. (2012)

Deconstructing the Hadley cell heat transport – Heaviside & Czaja (2012)

Temperature dependent climate projection deficiencies in CMIP5 models – Christensen & Boberg (2012)

Methane emissions from wetlands: biogeochemical, microbial, and modeling perspectives from local to global scales – Bridgham et al. (2012)

Coral record of reduced El Niño activity in the early 15th to middle 17th centuries – Hereid et al. (2012)

Zn isotope evidence for immediate resumption of primary productivity after snowball Earth – Kunzmann et al. (2012)

Improved estimates and understanding of global albedo and atmospheric solar absorption – Kim & Ramanathan (2012)

Detecting non-linear response of spring phenology to climate change by Bayesian analysis – Pope et al. (2012)

The uneven response of different snow measures to human-induced climate warming – Pierce & Cayan (2012)


CLASSIC OF THE WEEK: Williamson (1769)

An Attempt to Account for the Change of Climate, Which Has Been Observed in the Middle Colonies in North-America – Williamson (1769) [FULL TEXT]

Abstract: No abstract. First paragraph: “It is generally remarked by people who have resided long in Pennsylvania and the neighbouring Colonies, that within the last forty or fifty years there has been a very observable Change of Climate, that our winters are not so intensely cold, nor our summers so disagreeably warm as they have been.”

Citation: Hugh Williamson, Transactions of the American Philosophical Society, Vol. 1, (Jan. 1, 1769 – Jan. 1, 1771) (pp. 272-280).


About this series. When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. Here’s the archive for the research papers of previous weeks. If this sort of thing interests you, be sure to check out A Few Things Illconsidered. They also have a weekly posting containing lots of links to new research and other climate related news.

Posted in Climate science | 3 Comments »

New research from last week 51/2012

Posted by Ari Jokimäki on December 24, 2012

Merry christmas to all climate science fans! What would be better way to spend christmas than to read brand new climate research. That you find below a plenty.

NAtlAcid


Subtropical forests are threatened by their lack of resilience against long-term climate change

A Climate Change–Induced Threat to the Ecological Resilience of A Subtropical Monsoon Evergreen Broadleaved Forest in Southern China – Zhou et al. (2012)

Abstract: “Recent studies have suggested that tropical forests may not be resilient against climate change in the long term, primarily owing to predicted reductions in rainfall and forest productivity, increased tree mortality, and declining forest biomass carbon sinks. These changes will be caused by drought-induced water stress and ecosystem disturbances. Several recent studies have reported that climate change has increased tree mortality in temperate and boreal forests, or both mortality and recruitment rates in tropical forests. However, no study has yet examined these changes in the subtropical forests that account for the majority of China’s forested land. In the present study, we describe how the monsoon evergreen broadleaved forest has responded to global warming and drought stress using 32 years of data from forest observation plots. Due to an imbalance in mortality and recruitment, and changes in diameter growth rates between larger and smaller trees and among different functional groups, the average DBH of trees and forest biomass have decreased. Sap flow measurements also showed that larger trees were more stressed than smaller trees by the warming and drying environment. As a result, the monsoon evergreen broadleaved forest community is undergoing a transition from a forest dominated by a cohort of fewer and larger individuals to a forest dominated by a cohort of more and smaller individuals, with a different species composition, suggesting that subtropical forests are threatened by their lack of resilience against long-term climate change.”

Citation: Guoyi Zhou, Changhui Peng, Yuelin Li, Shizhong Liu, Qianmei Zhang, Xuli Tang, Juxiu Liu, Junhua Yan, Deqiang Zhang, Guowei Chu, Global Change Biology, DOI: 10.1111/gcb.12128.


Seabirds as sources of nitrous oxide and methane

Impact of seabird activity on nitrous oxide and methane fluxes from High Arctic tundra in Svalbard, Norway – Zhu et al. (2012)

Abstract: “In this study, tundra N2O and CH4 fluxes were measured from one seabird sanctuary (SBT) and two non-seabird colonies (NST-I and NST-II) in Ny-Ålesund (79°55′N, 11°56′E), Svalbard during the summers of 2008 and 2009. N2O and CH4 fluxes from SBT showed large temporal and spatial variations depending on the intensity of seabird activity. High seabird activity sites showed large N2O and CH4 emissions while low N2O and CH4 emissions, even CH4 uptake occurred at medium and low seabird activity sites. Overall the mean fluxes were 18.3 ± 3.6 μg N2O m−2 h−1 and 53.5 ± 20.3 μg CH4 m−2 h−1 from tundra SBT whereas tundra NST-I and NST-II represented a relatively weak N2O source (8.3 ± 13.2 μg N2O m−2 h−1) and strong CH4 sink (−82.8 ± 22.3 μg CH4 m−2 h−1). Seabird activity was the strongest control of N2O and CH4 fluxes compared with soil temperature and moisture, and high N2O and CH4 emissions were created by soil physical and chemical processes (the sufficient supply of nutrients NH4+–N, NO3–N, total nitrogen, total phosphorus and total carbon from seabird guano, seabird tramp and appropriate water content) related to the seabird activity. Our work suggests that tundra ecosystems impacted by seabird activity are the potential “hotspots” for N2O and CH4 emissions although these sources have been largely neglected at present. Furthermore the combination of seabird activity and warming climate will likely further enhance N2O and CH4 emissions from the High Arctic tundra.”

Citation: Zhu, R., Q. Chen, W. Ding, and H. Xu (2012), Impact of seabird activity on nitrous oxide and methane fluxes from High Arctic tundra in Svalbard, Norway, J. Geophys. Res., 117, G04015, doi:10.1029/2012JG002130.


Area change of glaciers in the Canadian Rocky Mountains, 1919 to 2006

Area change of glaciers in the Canadian Rocky Mountains, 1919 to 2006 – Tennant et al. (2012) [FULL TEXT]

Abstract: “Glaciers in the Canadian Rocky Mountains constitute an important freshwater resource. To enhance our understanding of the influence climate and local topography have on glacier area, large numbers of glaciers of different sizes and attributes need to be monitored over periods of many decades. We used Interprovincial Boundary Commission Survey (IBCS) maps of the Alberta–British Columbia (BC) border (1903–1924), BC Terrain Resource Information Management (TRIM) data (1982–1987), and Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) imagery (2000–2002 and 2006) to document planimetric changes in glacier cover in the central and southern Canadian Rocky Mountains between 1919 and 2006. Over this period, glacier cover in the study area decreased by 590 ± 70 km2 (40 ± 5%), 17 of 523 glaciers disappeared and 124 glaciers fragmented into multiple ice masses. Glaciers smaller than 1.0 km2 experienced the greatest relative area loss (64 ± 8%), and relative area loss is more variable with small glaciers, suggesting that the local topographic setting controls the response of these glaciers to climate change. Small glaciers with low slopes, low mean/median elevations, south to west aspects, and high insolation experienced the largest reduction in area. Similar rates of area change characterize the periods 1919–1985 and 1985–2001; −6.3 ± 0.6 km2 yr−1 (−0.4 ± 0.1% yr−1) and −5.0 ± 0.5 km2 yr−1 (−0.5 ± 0.1% yr−1), respectively. The rate of area loss, however, increased over the period 2001–2006; −19.3 ± 2.4 km2 yr−1 (−2.0 ± 0.2% yr−1). Applying size class-specific scaling factors, we estimate a total reduction in glacier cover in the central and southern Canadian Rocky Mountains for the period 1919–2006 of 750 km2 (30%).”

Citation: Tennant, C., Menounos, B., Wheate, R., and Clague, J. J.: Area change of glaciers in the Canadian Rocky Mountains, 1919 to 2006, The Cryosphere, 6, 1541-1552, doi:10.5194/tc-6-1541-2012, 2012.


Measurement methods affect the observed global dimming and brightening

Measurement Methods Affect the Observed Global Dimming and Brightening – Wang et al. (2012)

Abstract: “Surface incident solar radiation (G) determines our climate and environment. G has been widely observed with a single pyranometer since the late 1950s. Such observations have suggested a widespread decrease between the 1950s and 1980s (“global dimming”), i.e., at a rate of -3.5 W m−2 per decade (or -2% per decade) from 1960 to 1990. Since the early 1990s, the diffuse and direct components of G have been measured independently and a more accurate G was calculated by summing these two measurements. Data from this summation method have suggested that G has increased at a rate of 6.6 W m−2 per decade (3.6% per decade) from 1992 to 2002 (“brightening”) at selected sites. The brightening rates from these studies were also higher than those from a single pyranometer. In this paper, we used 17 years (1995-2011) parallel measurements by the two methods from nearly 50 stations to test whether these two measurement methods of G provide similar long-term trends. Our results show that although measurements of G by the two methods agree very well on a monthly time scale, the long-term trend from 1995 to 2011 determined by the single pyranometer is 2-4 W m−2 per decade less than that from the summation method. This difference of trends in the observed G is statistically significant. The dependence of trends of G on measurement methods uncovered here has an important implication for the widely reported “global dimming” and “brightening” based on datasets collected by different measurement methods, i.e., the dimming might have been less if measured with current summation methods.”

Citation: Kaicun Wang, Robert E. Dickinson, Qian Ma, John A. Augustine, and Martin Wild, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00482.1.


High-resolution bioclimate map of the world

A high-resolution bioclimate map of the world: a unifying framework for global biodiversity research and monitoring – Metzger et al. (2012)

Abstract: “Aim: To develop a novel global spatial framework for the integration and analysis of ecological and environmental data. Location: The global land surface excluding Antarctica. Methods: A broad set of climate-related variables were considered for inclusion in a quantitative model, which partitions geographic space into bioclimate regions. Statistical screening produced a subset of relevant bioclimate variables, which were further compacted into fewer independent dimensions using principal components analysis (PCA). An ISODATA clustering routine was then used to classify the principal components into relatively homogeneous environmental strata. The strata were aggregated into global environmental zones based on the attribute distances between strata to provide structure and support a consistent nomenclature. Results: The global environmental stratification (GEnS) consists of 125 strata, which have been aggregated into 18 global environmental zones. The stratification has a 30 arcsec resolution (equivalent to 0.86 km2 at the equator). Aggregations of the strata were compared with nine existing global, continental and national bioclimate and ecosystem classifications using the Kappa statistic. Values range between 0.54 and 0.72, indicating good agreement in bioclimate and ecosystem patterns between existing maps and the GEnS. Main conclusions: The GEnS provides a robust spatial analytical framework for the aggregation of local observations, identification of gaps in current monitoring efforts and systematic design of complementary and new monitoring and research. The dataset is available for non-commercial use through the GEO portal (http://www.geoportal.org).”

Citation: Marc J. Metzger, Robert G. H. Bunce, Rob H. G. Jongman, Roger Sayre, Antonio Trabucco, Robert Zomer, Global Ecology and Biogeography, DOI: 10.1111/geb.12022.


Last Glacial Maximum based climate sensitivity estimate is 2.5C with high probability of being under 4C

Can the Last Glacial Maximum constrain climate sensitivity? – Hargreaves et al. (2012)

Abstract: “We investigate the relationship between the Last Glacial Maximum (LGM) and climate sensitivity across the PMIP2 multi-model ensemble of GCMs, and find a correlation between tropical temperature and climate sensitivity which is statistically significant and physically plausible. We use this relationship, together with the LGM temperature reconstruction of Annan and Hargreaves (2012), to generate estimates for the equilibrium climate sensitivity. We estimate the equilibrium climate sensitivity to be about 2.5°C with a high probability of being under 4°C, though these results are subject to several important caveats. The forthcoming PMIP3/CMIP5 models were not considered in this analysis, as very few LGM simulations are currently available from these models. We propose that these models will provide a useful validation of the correlation presented here.”

Citation: Hargreaves, J. C., J. D. Annan, M. Yoshimori, and A. Abe-Ouchi (2012), Can the Last Glacial Maximum constrain climate sensitivity?, Geophys. Res. Lett., 39, L24702, doi:10.1029/2012GL053872.


Observed acidification trends in North Atlantic water masses

Observed acidification trends in North Atlantic water masses – Vázquez-Rodríguez et al. (2012) [FULL TEXT]

Abstract: “The lack of observational pH data has made it difficult to assess recent rates of ocean acidification, particularly in the high latitudes. Here we present a time series that spans over 27 yr (1981–2008) of high-quality carbon system measurements in the North Atlantic, which comprises fourteen cruises and covers the important water mass formation areas of the Irminger and Iceland Basins. We provide direct quantification of acidification rates in upper and intermediate North Atlantic waters. The highest rates were associated with surface waters and with Labrador Sea Water (LSW). The Subarctic Intermediate and Subpolar Mode Waters (SAIW and SPMW) showed acidification rates of −0.0019 ± 0.0001 and −0.0012 ± 0.0002 yr−1, respectively. The deep convection activity in the North Atlantic Subpolar Gyre injects surface waters loaded with anthropogenic CO2 into lower layers, provoking the remarkable acidification rate observed for LSW in the Iceland Basin (−0.0016 ± 0.0002 yr−1). An extrapolation of the observed linear acidification trends suggests that the pH of LSW could drop 0.45 units with respect to pre-industrial levels by the time atmospheric CO2 concentrations reach ~775 ppm. Under circulation conditions and evolution of CO2 emission rates similar to those of the last three decades, by the time atmospheric CO2 reaches 550 ppm, an aragonite undersaturation state could be reached in the cLSW of the Iceland Basin, earlier than surface SPMW.”

Citation: Vázquez-Rodríguez, M., Pérez, F. F., Velo, A., Ríos, A. F., and Mercier, H.: Observed acidification trends in North Atlantic water masses, Biogeosciences, 9, 5217-5230, doi:10.5194/bg-9-5217-2012, 2012.


In addition to ozone layer, Montreal Protocol protects also Earth’s hydroclimate

The Importance of the Montreal Protocol in Protecting the Earth’s Hydroclimate – Wu et al. (2012) [FULL TEXT]

Abstract: “The 1987 Montreal Protocol regulating emissions of chlorofluorocarbons (CFCs) and other ozone depleting substances (ODSs) was motivated primarily by the harm to human health and ecosystems arising from increased exposure to ultraviolet-B (UV-B) radiation associated with depletion the ozone layer. It is now known that the Montreal Protocol has helped reduce radiative forcing of the climate system since CFCs are greenhouse gases (GHGs), and that ozone depletion (which is now on the verge of reversing) has been the dominant driver of atmospheric circulation changes in the Southern Hemisphere in the last half century. In this paper we show that the Montreal Protocol also significantly protects the Earth’s hydroclimate. Using the Community Atmospheric Model, version 3 (CAM3), coupled to a simple mixed layer ocean, we demonstrate that in the ‘World Avoided’ (i.e. with CFC emissions not regulated), the subtropical dry zones would be substantially drier, and the middle and high latitude regions considerably wetter in the coming decade (2020-29) than a world without ozone depletion. Surprisingly, we find that these changes are very similar, in both pattern and magnitude, to those caused by projected increases in GHG concentrations over the same period. We further show that, by dynamical and thermodynamical mechanisms, both the stratospheric ozone depletion and increased CFCs contribute to these changes. Our results imply that, as a consequence of the Montreal Protocol, changes in the hydrological cycle in the coming decade will be only half as strong as what they otherwise would be.”

Citation: Yutian Wu, Lorenzo M. Polvani, Richard Seager, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00675.1.


Possible link between previous autumn sea ice cover and northern Eurasia winter precipitation

Autumn Sea Ice Cover, Winter Northern Hemisphere Annular Mode and Winter Precipitation in Eurasia – Li & Wang (2012)

Abstract: “This paper examines the impacts of the previous autumn sea ice cover (SIC) on the winter Northern Hemisphere annular mode (NAM) and winter precipitation in Eurasia. The coherent variations among the Kara–Laptev autumn SIC, winter NAM and Eurasian winter precipitation appear after the year 1982, which may prove useful for seasonal prediction of winter precipitation. From a physical point, the Kara–Laptev SIC and sea surface temperatures (SST) anomalies develop in autumn and remain in winter. Given that winter NAM is characterized by an Arctic–midlatitude seesaw centered over the Barents Sea and Kara–Laptev seas, it is closely linked to the Arctic forcing that corresponds to the Kara–Laptev sea ice increase (reduction) and the associated surface temperature cooling (warming). Moreover, based on both model simulations and observations, the diminishing Kara–Laptev Sea ice does induce positive SLP anomalies over high latitude Eurasia in winter, which is accompanied by a significant surface warming in northern Eurasia and cooling south of the Mediterranean. This SAT anomaly pattern facilitates increases of specific humidity in northern Eurasia with a major ridge extending southward along the East Asian coast. As a result, the anomalous Eurasian winter precipitation has a more zonal band structure.”

Citation: Fei Li and Huijun Wang, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00380.1.


The continuously increasing minimum temperature of Oahu – hot nights at Hawaii

Temporal and spatial trends in air temperature on the Island of Oahu, Hawaii – Safeeq et al. (2012)

Abstract: “We examined trends in minimum and maximum temperatures in the Oahu during the period of past 39 (1969–2007) and 25 (1983–2007) years. We found a strong spatial and temporal variability in the temperature trends on Oahu. During the past 39 years, island-wide minimum temperature has increased by 0.17 °C/decade and shows a considerable variability in trends at individual location. There was no detectable trend found in maximum temperature over the same time period. The year 1983 was identified as the change point in the island-wide minimum temperature. During the recent 25 years annual and summer maximum temperature showed a decline while minimum temperature continued to increase. Trend in diurnal temperature range (DTR) shows a decline during the past 39 years with a stronger decreasing trend during the recent 25 years. The trend in DTR for Oahu is much higher compared to the global DTR trend indicating a rapid warming in minimum temperature. Extreme temperature indices show a general warming during the past 39 years. There has been significant increase in tropical and warm nights at the two urban stations. Maximum temperature generally followed the Pacific Decadal Oscillation (PDO) except the period when there is an increase in Hawaii Rainfall Index (HRI). In contrast, minimum temperature showed better agreement with HRI compared to the PDO, at least up until 1999 after which it showed an increase. Despite the relative cooling in PDO during the recent decade an increase in minimum temperature can be attributed to a decline in HRI.”

Citation: Mohammad Safeeq, Alan Mair, Ali Fares, International Journal of Climatology, DOI: 10.1002/joc.3629.


Other studies from last week

Local temperatures inferred from plant communities suggest strong spatial buffering of climate warming across Northern Europe – Lenoir et al. (2012)

Farmers’ climate change beliefs and adaptation strategies for a water scarce future in Australia – Wheeler et al. (2012)

Long-term continuous atmospheric CO2 measurements at Baring Head, New Zealand – Brailsford et al. (2012) [FULL TEXT]

Sea-ice dynamics strongly promote Snowball Earth initiation and destabilize tropical sea-ice margins – Voigt & Abbot (2012) [FULL TEXT]

Ice sheet sources of sea level rise and freshwater discharge during the last deglaciation – Carlson & Clark (2012)

Simulation of the global contrail radiative forcing: A sensitivity analysis – Yi et al. (2012)

Global vegetation biomass change (1988–2008) and attribution to environmental and human drivers – Liu et al. (2012)

Lightning ground flash patterns over Paris area between 1992 and 2003: Influence of pollution? – Coquillat et al. (2012)

Changes in temperature and precipitation extremes observed in Modena, Italy – Boccolari & Malmusi (2012)

Bayesian analysis of climate change effects on observed and projected airborne levels of birch pollen – Zhang et al. (2012)

Variability of sea ice deformation rates in the Arctic and their relationship with basin-scale wind forcing – Herman & Glowacki (2012) [FULL TEXT]

Introducing subgrid-scale cloud feedbacks to radiation for regional meteorological and climate modeling – Alapaty et al. (2012)

Quantifying the sources of spread in climate change experiments – Geoffroy et al. (2012)

Weakened cyclones, intensified anticyclones and recent extreme cold winter weather events in Eurasia – Zhang et al. (2012) [FULL TEXT]

Site- and species-specific responses of forest growth to climate across the European continent – Babst et al. (2012)

Small range size and narrow niche breadth predict range contractions in South African frogs – Botts et al. (2012)

Does seaweed offer a solution for bioenergy with biological carbon capture and storage? – Hughes et al. (2012)

Climate versus emission drivers of methane lifetime against loss by tropospheric OH from 1860–2100 – John et al. (2012) [FULL TEXT]

Cloud condensation nuclei production associated with atmospheric nucleation: a synthesis based on existing literature and new results – Kerminen et al. (2012) [FULL TEXT]

What is the role of the observational dataset in the evaluation and scoring of climate models? – Gómez-Navarro et al. (2012)

The footprint of Alaskan tundra fires during the past half-century: implications for surface properties and radiative forcing – Rocha et al. (2012) [FULL TEXT]

Dynamics at the treeline: differential responses of Picea mariana and Larix laricina to climate change in eastern subarctic Québec – Dufour-Tremblay et al. (2012) [FULL TEXT]

Improvement in simulation of Eurasian winter climate variability with a realistic Arctic sea ice condition in an atmospheric GCM – Lim et al. (2012) [FULL TEXT]

Investigating the past and recent δ18O-accumulation relationship seen in Greenland ice cores – Buchardt et al. (2012) [FULL TEXT]

Methane emissions associated with the conversion of marshland to cropland and climate change on the Sanjiang Plain of northeast China from 1950 to 2100 – Li et al. (2012) [FULL TEXT]

Oxygen isotope ratios in the shell of Mytilus edulis: archives of glacier meltwater in Greenland? – Versteegh et al. (2012) [FULL TEXT]

On the Variability of Wind Power Input to the Oceans with a Focus on the Subpolar North Atlantic – Zhai & Wunsch (2012)

Environmental indifference? A critique of environmentally deterministic theories of peatland archaeological site construction in Ireland – Plunkett et al. (2012)

Implications of all season Arctic sea-ice anomalies on the stratosphere – Cai et al. (2012) [FULL TEXT]

Global CFC-11 (CCl3F) and CFC-12 (CCl2F2) measurements with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS): retrieval, climatologies and trends – Kellmann et al. (2012) [FULL TEXT]

On the role of the ocean in projected atmospheric stability changes in the Atlantic polar low region – Woollings et al. (2012)

Multiple causes of interannual sea surface temperature variability in the equatorial Atlantic Ocean – Richter et al. (2012)


CLASSIC OF THE WEEK: Man’s Inadvertent Modification of Weather and Climate

Man’s Inadvertent Modification of Weather and Climate – Precidential Council on Environmental Quality (1970) [FULL TEXT]

Abstract: No abstract. First paragraph: “Man may be changing his weather. And if he is, the day may come when he will either freeze by his own hand or drown. The delicate balances within the atmosphere and the history of climatic change in the past suggest that through his inadvertent actions he may be driving the atmosphere either to a disastrous ice age – or as bad – to a catastrophic melting of the ice caps. Either may literally be possible, but it depends on just what he is doing to the atmosphere. He does not know for sure.”

Citation: Bull. Amer. Meteor. Soc., 51, 1043–1048, doi: http://dx.doi.org/10.1175/1520-0477(1970)0512.0.CO;2.


About this series. When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. Here’s the archive for the research papers of previous weeks. If this sort of thing interests you, be sure to check out A Few Things Illconsidered. They also have a weekly posting containing lots of links to new research and other climate related news.

Posted in Climate science | 1 Comment »

New research from last week 50/2012

Posted by Ari Jokimäki on December 17, 2012

These weekly new research posts will not be published anymore after the end of this year. New research will be communicated in some different format in the future. We are working on it in Skeptical Science author community. I’m not yet sure how this might affect my output in my Facebook and Twitter pages, but it is probable that number of papers communicated through those channels will drop.


Multi-decadal Climate Variability and the “Warming Hole” in North America

Multi-decadal Climate Variability and the “Warming Hole” in North America – results from CMIP5 20th and 21st Century Climate Simulations – Kumar et al. (2012) [FULL TEXT]

Abstract: “The ability of Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models to simulate the 20th 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 Wm−2 representative concentration pathways (RCP8.5 and RCP4.5). We have analyzed simulations from 22 CMIP5 climate models including all their ensemble members, a total of 192 climate realizations. We have employed a non-parametric trend detection method, and an alternative perspective emphasizing trend variability. Observations show multi-decadal variability in the sign and magnitude of the trend, where the 20th century temperature trend over the eastern United States appears to be associated with low frequency (multi-decadal) variability in the North Atlantic temperatures. Most CMIP5 climate models simulate significantly lower ‘relative power’ in the North Atlantic multi-decadal oscillations than observed. Models that have relatively higher skill in simulating the North-Atlantic multi-decadal oscillation also are more likely to reproduce the warming hole. We also find that the trend variability envelope simulated by multiple CMIP5 climate models brackets the observed warming hole. Based on the multi-model analysis, we find that in the 21st century climate simulations the presence or absence of the warming hole would depend upon the future emission scenarios; the RCP8.5 scenario indicates a disappearance of the warming hole, while the RCP4.5 scenario shows some chance (10-20%) of the warming hole’s reappearance in the latter half of the 21st century consistent with CO2 stabilization.”

Citation: Sanjiv Kumar, James Kinter, Paul A. Dirmeyer, Zaitao Pan, and Jennifer Adams, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00535.1.


Annual maximum daily precipitation has increased globally

Global increasing trends in annual maximum daily precipitation – Westra et al. (2012)

Abstract: “This study investigates the presence of trends in annual maximum daily precipitation timeseries obtained from a global dataset of 8326 high quality land-based observing stations with more than 30 years of record over the period from 1900 to 2009. Two complementary statistical techniques were adopted to evaluate the possible non-stationary behaviour of this precipitation data. The first was a Mann-Kendall non-parametric trend test, and was used to evaluate the existence of monotonic trends. The second was a non-stationary generalised extreme value analysis, and was used to determine the strength of association between the precipitation extremes and globally averaged near-surface temperature. The outcomes are that statistically significant increasing trends can be detected at the global scale, with close to two-thirds of stations showing increases. Furthermore, there is a statistically significant association with globally averaged near-surface temperature, with the median intensity of extreme precipitation changing in proportion with changes in global mean temperature at a rate of between 5.9% and 7.7% per degree, depending on the method of analysis. This ratio was robust irrespective of record length or time period considered, and was not strongly biased by the uneven global coverage of precipitation data. Finally, there is a distinct meridional variation, with the greatest sensitivity occurring in the tropics and higher latitudes, and minima around 13°S and 11°N. The greatest uncertainty was near the equator due to the limited number of sufficiently long precipitation records, and there remains an urgent need to improve data collection in this region to better constrain future changes in tropical precipitation.”

Citation: Seth Westra, Lisa V. Alexander, and Francis W. Zwiers, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00502.1.


Human influence shows in extratropical Southern Hemisphere summer precipitation

Human influence on extratropical Southern Hemisphere summer precipitation – Fyfe et al. (2012)

Highlights: •Observed precipitation trends inconsistent with simulated internal variability; •Observed precipitation trends mainly due to anthropogenic and natural forcings; •Specifically from GHG and ozone changes, with opposing influence from aerosols.

Abstract: “Observations of extratropical Southern Hemisphere austral summer precipitation over recent decades show mid-latitude drying and high-latitude moistening. Here we show that the observed precipitation trends in two datasets are inconsistent with simulated internal variability, but are closely consistent with trends simulated in response to historical changes in anthropogenic and natural forcings. Simulations with individual anthropogenic and natural forcings suggest that the observed pattern of precipitation change is substantially forced by anthropogenic greenhouse gas and ozone changes, with an opposing influence from aerosols. Our results demonstrate that human influence had a significant impact on precipitation across the mid and high latitudes of the Southern Hemisphere, changes which are expected to have a profound impact on Southern Ocean stratification and hence on ocean-atmosphere heat and carbon fluxes.”

Citation: Fyfe, J. C., N. P. Gillett, and G. J. Marshall (2012), Human influence on extratropical Southern Hemisphere summer precipitation, Geophys. Res. Lett., 39, L23711, doi:10.1029/2012GL054199.


Quaternary International is publishing a special issue on dendrochronology in Asia

Dendrochronology in Asia – Quaternary International (2013)

Selected quotes from editorial: “In August 2011, the Second International Asian Dendrochronological Conference was held in Xian, China. During five days, over 150 participants from China, India, Thailand, Korea, Nepal, Japan, Pakistan, Iran, Mongolia, and countries outside of Asia gathered, and more than 65 presentations were given. A wide range of the dendrochronological sciences was covered in sessions dedicated to dendroclimatology, dendroecology, dendroarchaeology, dendrohydrology, wood anatomy, and stable isotope applications… …In this special issue of Quaternary International, selected papers presented at the conference have been assembled. These papers provide a nice overview of the current state of Asian dendrochronology, albeit with focus on China.”

Citation: Quaternary International, Volume 283, Pages 1-146 (14 January 2013), edited by Hans Linderholm, Yu Liu, Steven Leavitt and Eryuan Liang.


Deforestation can lead to irreversible state shifts where the forest vegetation cannot recover

Physical and biological feedbacks of deforestation – Runyan et al. (2012)

Highlights: •Forest vegetation can enhance conditions favorable to its own existence; •Removal of forest vegetation can alter conditions necessary to sustain growth; •Deforestation can lead to irreversible state shifts.

Abstract: “Forest vegetation can interact with its surrounding environment in ways that enhance conditions favorable for its own existence. Removal of forest vegetation has been shown to alter these conditions in a number of ways, thereby inhibiting the reestablishment of the same community of woody plants. The effect of vegetation on an environmental variable along with vegetation susceptibility to the associated environmental conditions may imply a positive feedback: Changes in the internal conditions controlling this variable such as deforestation could inhibit the reestablishment of woody vegetation cover that in turn would act to further degrade the conditions necessary for forest regeneration. Understanding these feedbacks is important because in some cases where these feedbacks are present, deforestation can lead to irreversible state shifts where the forest vegetation cannot recover. In this review, we examine the different cases in which deforestation can lead to a loss of conditions necessary to sustain forest vegetation. We examine the spatial scale and extent of each feedback in addition to considering the temporal scale over which a feedback may be considered irreversible. Juxtaposing the spatial extent of these feedbacks with a map of deforestation enables the identification and discussion of at-risk areas to state changes following deforestation. Last, we discuss the economic implications of these feedbacks and how socioeconomic factors can affect the convergence of a system to a given stable state.”

Citation: Runyan, C. W., P. D’Odorico, and D. Lawrence (2012), Physical and biological feedbacks of deforestation, Rev. Geophys., 50, RG4006, doi:10.1029/2012RG000394.


Montreal Protocol has prevented climate change and catastrophic ozone loss

“World avoided” simulations with the Whole Atmosphere Community Climate Model – Garcia et al. (2012)

Highlights: •The Montreal Protocol has prevented climate change and catastrophic ozone loss; •Heterogeneous chemistry hastens ozone collapse but is not needed to produce it; •The collapse of tropical ozone is reversed quickly if ODS emissions cease.

Abstract: “We use the Whole Atmosphere Community Climate Model, coupled to a deep ocean model, to investigate the impact of continued growth of halogenated ozone depleting substances (ODS) in the absence of the Montreal Protocol. We confirm the previously reported result that the growth of ODS leads to a global collapse of the ozone layer in mid-21st century, with column amounts falling to 100 DU or less at all latitudes. We also show that heterogeneous activation of chlorine in the lower stratosphere hastens this collapse but is not essential to produce it. The growth of ODS, which are also greenhouse gases, produces a radiative forcing of 4 W m−2 by 2070, nearly equal that of the non-ODS greenhouse gases CO2, CH4, and N2O in the RCP4.5 scenario of IPCC. This leads to surface warming of over 2 K in the tropics, 6 K in the Arctic, and close to 4 K in Antarctica in 2070 compared to the beginning of the century. We explore the reversibility of these impacts following complete cessation of ODS emissions in the mid-2050s. We find that impacts are reversed on various time scales, depending on the atmospheric lifetime of the ODS that cause them. Thus ozone in the lower stratosphere in the tropics and subtropics recovers very quickly because the ODS that release chlorine and bromine there (e.g., methyl chloroform and methyl bromide) have short atmospheric lifetimes and are removed within a few years. On the other hand, ozone depletion in the polar caps and global radiative forcing depend on longer-lived ODS, such that much of these impacts persist through the end of our simulations  in 2070.”

Citation: Garcia, R. R., D. E. Kinnison, and D. R. Marsh (2012), “World avoided” simulations with the Whole Atmosphere Community Climate Model, J. Geophys. Res., 117, D23303, doi:10.1029/2012JD018430.


New study says Laki eruption contributed to 1783-1784 winter cooling

Climatic impact of the long-lasting 1783 Laki eruption: Inapplicability of mass-independent sulfur isotopic composition measurements – Schmidt et al. (2012)

Highlights: •1783-84 CE Laki eruption produced multiyear impact on NH surface temperatures, •Laki produced stratospheric injection and contributed to 1783-84 winter cooling, •S isotope measurements not applicable for interpreting Laki’s climatic impact.

Abstract: “The long-lasting 1783–1784 CE Laki flood lava eruption in Iceland released around 120 Tg of sulfur dioxide into the upper troposphere/lower stratosphere. Northern Hemisphere temperature proxy records of the 1780s indicate below-average temperatures for up to three years following the eruption. The very warm summer of 1783 in Europe, which was followed by a very cold winter, may have been caused by the eruption, but the mechanisms are not yet well understood. Some studies attributed the cold winter 1783–1784 to natural variability of climate. However, our climate model simulations show that the Laki radiative effects lasted long enough to contribute to the winter cooling. We suggest that sulfur isotopic composition measurements obtained using samples from Greenland ice cores do not provide evidence of either a short-lived volcanic aerosol cloud or a short-lived climatic impact of the Laki eruption. In fact, the applicability of mass-independent sulfur isotopic composition measurements for interpreting the climatic impact of any high-latitude eruption remains yet to be demonstrated.”

Citation: Schmidt, A., T. Thordarson, L. D. Oman, A. Robock, and S. Self (2012), Climatic impact of the long-lasting 1783 Laki eruption: Inapplicability of mass-independent sulfur isotopic composition measurements, J. Geophys. Res., 117, D23116, doi:10.1029/2012JD018414.


It’s all tiny details nowadays: Impact of dust particle non-sphericity on climate simulations

Impact of dust particle non-sphericity on climate simulations – Räisänen et al. (2012)

Abstract: “Although mineral aerosol (dust) particles are irregular in shape, they are treated as homogeneous spheres in climate model radiative transfer calculations. Here, we test the effect of dust particle non-sphericity in the ECHAM5.5-HAM2 global aerosol–climate model. The short-wave optical properties of the two insoluble dust modes in HAM2 are modelled using an ensemble of spheroids that has been optimized to reproduce the optical properties of dust-like aerosols, thereby providing a significant improvement over spheres. First, the direct radiative effects (DRE) of dust non-sphericity were evaluated diagnostically, by comparing spheroids with both volume-equivalent and volume-to-area (V/A) equivalent spheres. In the volume-equivalent case, the short-wave DRE of insoluble dust at the surface and at the top of the atmosphere (TOA) was slightly smaller (typically by 3–4%) for spheroidal than for spherical dust particles. This rather small difference stems from compensating non-sphericity effects on the dust optical thickness and asymmetry parameter. In the V/A-equivalent case, the difference in optical thickness was virtually eliminated and the DRE at the TOA (surface) was ∼20% (∼13%) smaller for spheroids than for spheres, due to a larger asymmetry parameter. Even then, however, the global-mean DRE of non-sphericity was only 0.055 W m−2 at the TOA and 0.070 W m−2 at the surface. Subsequently, the effects of dust non-sphericity were tested interactively in simulations in which ECHAM5.5-HAM2 was coupled to a mixed-layer ocean model. Consistent with the rather small radiative effects noted above, the climatic differences from simulations with spherical dust optics were generally negligible.”

Citation: P. Räisänen, P. Haapanala, C. E. Chung, M. Kahnert, R. Makkonen, J. Tonttila, T. Nousiainen, Quarterly Journal of the Royal Meteorological Society, DOI: 10.1002/qj.2084.


Clouds are important also for Martian climate

The influence of radiatively active water ice clouds on the Martian climate – Madeleine et al. (2012)

Highlights: •Radiatively active clouds (RAC) are implemented in the LMD global climate model; •Whatever the season, including RAC is required to fit the observed temperatures; •Renewed attention on the polar regions, where cold biases remain, is needed.

Abstract: “Radiatively active water ice clouds (RAC) play a key role in shaping the thermal structure of the Martian atmosphere. In this paper, RAC are implemented in the LMD Mars Global Climate Model (GCM) and the simulated temperatures are compared to Thermal Emission Spectrometer observations over a full year. RAC change the temperature gradients and global dynamics of the atmosphere and this change in dynamics in turn implies large-scale adiabatic temperature changes. Therefore, clouds have both a direct and indirect effect on atmospheric temperatures. RAC successfully reduce major GCM temperature biases, especially in the regions of formation of the aphelion cloud belt where a cold bias of more than 10 K is corrected. Departures from the observations are however seen in the polar regions, and highlight the need for better modeling of cloud formation and evolution.”

Citation: Madeleine, J.-B., F. Forget, E. Millour, T. Navarro, and A. Spiga (2012), The influence of radiatively active water ice clouds on the Martian climate, Geophys. Res. Lett., 39, L23202, doi:10.1029/2012GL053564.


On the statistical significance of surface air temperature trends in the Eurasian Arctic region

On the statistical significance of surface air temperature trends in the Eurasian Arctic region – Franzke (2012)

Highlights: •I am using a novel method to test the significance of temperature trends; •In the Eurasian Arctic region only 17 stations show a significant trend; •I find that in Siberia the trend signal has not yet emerged.

Abstract: “This study investigates the statistical significance of the trends of station temperature time series from the European Climate Assessment & Data archive poleward of 60°N. The trends are identified by different methods and their significance is assessed by three different null models of climate noise. All stations show a warming trend but only 17 out of the 109 considered stations have trends which cannot be explained as arising from intrinsic climate fluctuations when tested against any of the three null models. Out of those 17, only one station exhibits a warming trend which is significant against all three null models. The stations with significant warming trends are located mainly in Scandinavia and Iceland.”

Citation: Franzke, C. (2012), On the statistical significance of surface air temperature trends in the Eurasian Arctic region, Geophys. Res. Lett., 39, L23705, doi:10.1029/2012GL054244.


Ozone might have been one factor in Snowball Earth

Radiative effects of ozone on the climate of a Snowball Earth – Yang et al. (2012) [FULL TEXT]

Abstract: “Some geochemical and geological evidence has been interpreted to suggest that the concentration of atmospheric oxygen was only 1–10 % of the present level in the time interval from 750 to 580 million years ago when several nearly global glaciations or Snowball Earth events occurred. This low concentration of oxygen would have been accompanied by a lower ozone concentration than exists at present. Since ozone is a greenhouse gas, this change in ozone concentration would alter surface temperature, and thereby could have an important influence on the climate of the Snowball Earth. Previous works that have focused either on initiation or deglaciation of the proposed Snowball Earth has not taken the radiative effects of ozone changes into account. We address this issue herein by performing a series of simulations using an atmospheric general circulation model with various ozone concentrations. Our simulation results demonstrate that, as ozone concentration is uniformly reduced from 100 % to 50 %, surface temperature decreases by approximately 0.8 K at the Equator, with the largest decreases located in the middle latitudes reaching as high as 2.5 K. When ozone concentration is reduced and its vertical and horizontal distribution is simultaneously modulated, surface temperature decreases by 0.4–1.0 K at the Equator and by 4–7 K in polar regions. These results here have uncertainties, depending on model parameterizations of cloud, surface snow albedo, and relevant feedback processes, while they are qualitatively consistent with radiative-convective model results that do not involve such parameterizations and feedbacks. These results suggest that ozone variations could have had a moderate impact on the climate during the Neoproterozoic glaciations.”

Citation: Yang, J., Hu, Y., and Peltier, W. R.: Radiative effects of ozone on the climate of a Snowball Earth, Clim. Past, 8, 2019-2029, doi:10.5194/cp-8-2019-2012, 2012.


In future there will be climates unlike the present ones in some Earth zones

Modelling future no-analogue climate distributions: A world-wide phytoclimatic niche-based survey – García-López & Allué (2012)

Highlights: ► The percentage of the world surface that will foreseeably be occupied by no-analogue climates by 2080 ranges between 3.5% and 17.5% ► We present a numerical and cartographic evaluation of these no-analogue climatic zones ► The bulk of the no-analogue surface area will foreseeably be located in the Northern hemisphere (> 80%), more probably in tropical and subtropical latitudes between 10 degrees latitude South and 30 degrees latitude North. ► 32 of the 34 hotspots defined for the planet, especially tropical forests in South America and Asia will be affected by no-analog conditions. 6.8% of these conservation-critical surfaces are predicted as no-analogue areas ► Population density is greater in the areas that will probably develop no-analogue climates in the future than in those that will not.

Abstract: “By the end of the 21st century in some zones the accelerating climate change affecting this planet will create factorial combinations unknown at this time, which will give rise to climates unlike the present ones. This study presents a numerical and cartographic evaluation of these no-analogue climatic zones, whose consequences for existing ecosystems are quite unpredictable, using a method based on the convex hull in a climate hyperspace and 12 future climate projections for 2080. The percentage of the world surface that will foreseeably be occupied by no-analogue climates by 2080 ranges between 3.5% and 17.5%. The bulk of the no-analogue surface area will foreseeably be located in the Northern hemisphere (> 80%), with more elevated risk in tropical and subtropical latitudes between 10 degrees latitude South and 30 degrees latitude North, preferentially in Africa, South America, the Arabian Peninsula, the Indian Peninsula, the North-West of the Gulf of Mexico, Eastern China and Polynesia. Mean temperatures would appear to be the variables most influencing the process. This affects 32 of the 34 hotspots defined for the planet, especially tropical forests in South America and Asia. 6.8% of these conservation-critical surfaces are predicted as no-analogue areas. Population density is greater in the areas that will probably develop no-analogue climates in the future than in those that will not.”

Citation: Javier M. García-López, Carmen Allué, Global and Planetary Change, http://dx.doi.org/10.1016/j.gloplacha.2012.12.001.


Other studies from last week

Global climate change in large European rivers: long-term effects on macroinvertebrate communities and potential local confounding factors – Floury et al. (2012)

Impacts of Atmospheric Temperature Trends on Tropical Cyclone Activity – Vecchi et al. (2012)

The Influence of Atlantic Tropical Cyclones on Drought over the Eastern US (1980-2007) – Kam et al. (2012)

Faint young Sun problem more severe due to ice-albedo feedback and higher rotation rate of the early Earth – Kienert et al. (2012)

The great Arctic cyclone of August 2012 – Simmonds & Rudeva (2012)

Climate change impacts on Central Asian water resources – Malsy et al. (2012) [FULL TEXT]

Carbon emissions from land use and land-cover change – Houghton et al. (2012) [FULL TEXT]

On the Measurement of Heatwaves – Perkins & Alexander (2012)

A near real-time satellite-based global drought climate data record – AghaKouchak & Nakhjiri (2012) [FULL TEXT]

The role of upper-level dynamics and surface processes for the Pakistan flood of July 2010 – Martius et al. (2012)

Recent tropospheric ozone changes – A pattern dominated by slow or no growth – Oltmans et al. (2012)

Brief communication “Stratospheric winds, transport barriers and the 2011 Arctic ozone hole” – Olascoaga et al. (2012)

The impact of greenhouse gases on past changes in tropospheric ozone – Lang et al. (2012)

Quantifying the seasonal “breathing” of the Antarctic ice sheet – Ligtenberg et al. (2012)

The effect of snow cover on lemming population cycles in the Canadian High Arctic – Bilodeau et al. (2012)

A 20 year independent record of sea surface temperature for climate from Along-Track Scanning Radiometers – Merchant et al. (2012)

Assessment of regional climate model simulation estimates over the northeast United States – Rawlins et al. (2012)

Radiation budget changes with dry forest clearing in temperate Argentina – Houspanossian et al. (2012)

Adaptation to climate change through the choice of cropping system and sowing date in sub-Saharan Africa – Waha et al. (2012)

Global burned area and biomass burning emissions from small fires – Randerson et al. (2012)


CLASSIC OF THE WEEK: Stoney (1898)

Of Atmospheres upon Planets and Satellites – Stoney (1898) [FULL TEXT]

Abstract: No abstract.

Citation: Stoney, G. Johnstone, Astrophysical Journal, vol. 7, p.25, DOI: 10.1086/140435.


About this series. When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. Here’s the archive for the research papers of previous weeks. If this sort of thing interests you, be sure to check out A Few Things Illconsidered. They also have a weekly posting containing lots of links to new research and other climate related news.

Posted in Climate science | Leave a Comment »

New research from last week 49/2012

Posted by Ari Jokimäki on December 10, 2012

Global warming impacts many things. It’s actually quite difficult to come up with things within Earth system that are not affected by global warming. In this week’s papers we see that Greenland glaciers accelerate, frequency and intensity of temperature extremes change, air pollution is getting worse, Arctic sea ice amount is decreasing while Siberian snow cover is thickening, Northern Hemisphere thermal growing season is getting longer, corals are trying to expand polewards but ocean acidification doesn’t let them to do that, western North America gets dry and vegetation declines, sea level rises, …

But all this doesn’t mean anything because climate has changed in the past, right? Well, also mass extinctions have happened in the past.

NHgrowSeason


Spreading of warm ocean waters around Greenland as a possible cause for glacier acceleration

Spreading of warm ocean waters around Greenland as a possible cause for glacier acceleration – Rignot et al. (2013)

Abstract: “We examine the pattern of spreading of warm subtropical-origin waters around Greenland for the years 1992-2009 using a high-resolution (4 km horizontal grid) coupled ocean and sea-ice simulation. The simulation, provided by the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) project, qualitatively reproduces the observed warming of subsurface waters in the subpolar gyre associated with changes of the North Atlantic atmospheric state that occurred in the mid-1990s. The modeled subsurface ocean temperature warmed by 1.5°C in southeast and southwest Greenland during 1994-2005 and subsequently cooled by 0.5°C; modeled subsurface ocean temperature increased by 2-2.5°C in central and then northwest Greenland during 1997-2005 and stabilized thereafter, while it increased after 2005 by <0.5°C in north Greenland. Comparisons with in situ measurements off the continental shelf in the Labrador and Irminger Seas indicate that the model initial conditions were 0.4°C too warm in the south but the simulated warming is correctly reproduced; while measurements from eastern Baffin Bay reveal that the model initial conditions were 1.0°C too cold in the northwest but the simulated ocean warming brought modeled temperature closer to observations, i.e. the simulated warming is 1.0°C too large. At several key locations, the modeled oceanic changes off the shelf and below the seasonal mixed layer were rapidly transmitted to the shelf within troughs towards (model-unresolved) fjords. Unless blocked in the fjords by shallow sills, these warm subsurface waters had potential to propagate down the fjords and melt the glacier fronts. Based on model sensitivity simulations from an independent study (Xu and others, 2012), we show that the oceanic changes have very likely increased the subaqueous melt rates of the glacier fronts, and in turn impacted the rates of glacier flow."

Citation: Rignot, E.; Fenty, I.; Menemenlis, D.; Xu, Y., Annals of Glaciology, Volume 53, Number 60, November 2012 , pp. 257-266(10), DOI: http://dx.doi.org/10.3189/2012AoG60A136.


Collapse of the terrestrial ecosystem predated that of the marine ecosystem during Permian mass extinction

Microbial-algal community changes during the latest Permian ecological crisis: Evidence from lipid biomarkers at Cili, South China – Luo et al. (2013)

Highlights: ► Eukaryotic algae were very low in abundance in the microbialite interval. ► Cyanobacteria, anaerobic bacteria, archaea and/or acritarchs were the main microbes in the ocean after the main oceanic metazoan mass extinction. ► Collapse of the terrestrial ecosystem predated that of the marine ecosystem. ► Intensive wildfire occurred simultaneously with the collapse of the terrestrial ecosystem but, preceded that of the marine ecosystem.

Abstract: “Microbialites flourished globally immediately following the latest Permian mass extinction. In this study, lipid biomarker records were analyzed in the Cili section (Hunan Province, South China) in order to determine the types of microbes involved in microbialite formation and their response to contemporaneous environmental changes. Various biomarkers were identified in the aliphatic and aromatic fractions using gas chromatography (GC) and GC-mass spectrometry (GC-MS). Low abundance of steranes in the microbialite layer suggests that it did not contain large amounts of algae, in striking contrast to the abundant algal fossils and algal-derived steranes present in the underlying (pre-crisis) skeletal limestone. Although pristine/phytane (Pr/Ph) ratios increased in the microbialite layer, covariation of Pr/Ph with the ratio of low- to high-molecular-weight n-alkanes (C20-/C20 +) suggests that the former proxy was controlled by microbial (particularly cyanobacterial) inputs rather than by redox conditions. The microbialite also yielded low ratios of hopanes to short-chain n-alkanes (HP/Lalk) and high abundances of C21n-alkylcyclohexane, indicating that, in addition to cyanobacteria, anaerobic bacteria, archaea, and possibly acritarchs flourished in the aftermath of the marine extinction event. The upper part of the thinly bedded micritic limestone overlying the microbialite exhibits a bimodal distribution of n-alkanes as well as increased abundances of extended tricyclic terpanes and steranes, suggesting a return of habitable shallow-marine conditions for eukaryotic algae several hundred thousand years after the latest Permian mass extinction. Increases in the dibenzofuran ratio (i.e., DBF/(DBF+DBT+F)) and in the coronene to phenanthrene ratio (Cor/P) in the skeletal limestone immediately below the microbialite are evidence of enhanced soil erosion rates and wildfire intensity, marking the collapse of terrestrial ecosystems. The terrestrial crisis thus slightly preceded the marine biotic crisis in the South China region, to which it may have been a major contributing factor.”

Citation: Genming Luo, Yongbiao Wang, Kliti Grice, Steve Kershaw, Thomas J. Algeo, Xiaoyan Ruan, Hao Yang, Chengling Jia, Shucheng Xie, Global and Planetary Change, http://dx.doi.org/10.1016/j.gloplacha.2012.11.015.


Can a decadal forecasting system predict temperature extreme indices?

Can a decadal forecasting system predict temperature extreme indices? – Hanlon et al. (2013)

Abstract: “Daily maximum and minimum summer temperatures have increased throughout the majority of Europe over the past few decades, along with the frequency and intensity of heatwaves. It is essential to learn whether this rise is expected to continue in the future for adaptation purposes. A study of predictability of European temperature indices, with the Met Office Hadley Centre Decadal Prediction System (DePreSys) has revealed significant skill in predictions of 5/10-year average indices of the summer mean and maximum 5-day average temperatures based on daily maximum and minimum temperatures for a large area of Europe, particularly in the Mediterranean. In contrast, the decadal forecasts of winter mean/minimum 5-day average temperature indices show poorer skill than the summer indices. The UK shows significant skill in some cases but less than for the European/Mediterranean regions. Comparison of two parallel ensembles, one initialised with observations, one without initialisation has shown that the skill largely originates from external forcing. However, there were a few cases which had hints of additional skill in forecasts of decadal mean indices due to the initialisation. Model realisations of extreme indices can have large biases compared to observations that are different from those of the mean climate indices. Several methods were tested for correcting biases, as well as for testing the significance and quantifying uncertainty of the results to rule out cases of spurious skill. Bias correction of each index individually is required as biases vary across different extremes.”

Citation: Helen M. Hanlon, Gabriele C. Hegerl, and Simon F. B. Tett, Doug M. Smith, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00512.1.


Climate change might increase the frequency of bad ozone days considerably in Germany

Ozone and its projection in regard to climate change – Melkonyan & Wagner (2013)

Highlights: ► Ozone dependence on NOx and temperature at industrial and rural stations. ► Prediction of number of days with ozone exceedances in terms of climate change. ► Frequency of bad ozone days increases by 135% at the industrial station. ► Frequency of bad ozone days increases by 87% at the rural station. ► Ozone forming potential is significantly higher in rural areas than in urban ones.

Abstract: “In this paper, the dependence of ozone-forming potential on temperature was analysed based on data from two stations (with an industrial and rural background, respectively) in North Rhine-Westphalia, Germany, for the period of 1983–2007. After examining the interrelations between ozone, NOx and temperature, a projection of the days with ozone exceedance (over a limit value of a daily maximum 8-h average ≥ 120 μg m−3 for 25 days per year averaged for 3 years) in terms of global climate change was made using probability theory and an autoregression integrated moving average (ARIMA) model. The results show that with a temperature increase of 3 K, the frequency of days when ozone exceeds its limit value will increase by 135% at the industrial station and by 87% at the rural background station.”

Citation: Ani Melkonyan, Patrick Wagner, Atmospheric Environment, Volume 67, March 2013, Pages 287–295, http://dx.doi.org/10.1016/j.atmosenv.2012.10.023.


Arctic sea ice loss helps to explain Siberian snow cover thickening

Simulated Siberian snow cover response to observed Arctic sea ice loss, 1979–2008 – Ghatak et al. (2012)

Highlights: •Examine a possible causal link between Arctic sea ice and Siberian snow cover, •CAM3 experiments were designed, •Arctic Ocean surface forcing is necessary to induce a Siberian snow signal.

Abstract: “The loss of Arctic sea ice has wide-ranging impacts, some of which are readily apparent and some of which remain obscure. For example, recent observational studies suggest that terrestrial snow cover may be affected by decreasing sea ice. Here, we examine a possible causal link between Arctic sea ice and Siberian snow cover during the past 3 decades using a suite of experiments with the National Center for Atmospheric Research Community Atmospheric Model version 3. The experiments were designed to isolate the influence of surface conditions within the Arctic Ocean from other forcing agents such as low-latitude sea surface temperatures and direct radiative effects of increasing greenhouse gases. Only those experiments that include the observed evolution of Arctic sea ice and sea surface temperatures result in increased snow depth over Siberia, while those that maintain climatological values for Arctic Ocean conditions result in no snow signal over Siberia. In the former, Siberian precipitation and air temperature both increase, but because surface air temperatures remain below freezing during most months, the snowpack thickens over this region. These results suggest that Arctic Ocean surface forcing is necessary and sufficient to induce a Siberian snow signal, and that other forcings in combination can modulate the strength and geographic extent of the response.”

Citation: Ghatak, D., C. Deser, A. Frei, G. Gong, A. Phillips, D. A. Robinson, and J. Stroeve (2012), Simulated Siberian snow cover response to observed Arctic sea ice loss, 1979–2008, J. Geophys. Res., 117, D23108, doi:10.1029/2012JD018047.


Northern Hemisphere thermal growing season has become longer but biospheric carbon uptake hasn’t

Thermal growing season and timing of biospheric carbon uptake across the Northern Hemisphere – Barichivich et al. (2012)

Highlights: •The decade of the 2000s recorded the longest thermal growing seasons since 1950, •The extension has been symmetrical since 2005 due to strong autumn warming, •Thermal growing season length is not correlated with biospheric uptake period.

Abstract: “Gridded daily temperature from 1950 to 2011 and atmospheric CO2 concentration data from high-latitude observing stations and the CarbonTracker assimilation system are used to examine recent spatiotemporal variability of the thermal growing season and its relationship with seasonal biospheric carbon uptake and release in the Northern Hemisphere. The thermal growing season has lengthened substantially since 1950 but most of the lengthening has occurred during the last three decades (2.9 days decade−1, p < 0.01 for 1980–2011), with stronger rates of extension in Eurasia (4.0 days decade−1, p < 0.01) than in North America (1.2 days decade−1, p > 0.05). Unlike most previous studies, which had more limited data coverage over the past decade, we find that strong autumn warming of about 1°C during the second half of the 2000s has led to a significant shift toward later termination of the thermal growing season, resulting in the longest potential growing seasons since 1950. On average, the thermal growing season has extended symmetrically by about a week during this period, starting some 4.0 days earlier and ending about 4.3 days later. The earlier start of the thermal growing season is associated with earlier onset of the biospheric carbon uptake period at high northern latitudes. In contrast, later termination of the growing season is associated with earlier termination of biospheric carbon uptake, but this relationship appears to have decoupled since the beginning of the period of strong autumn warming during the second half of the 2000s. Therefore, owing to these contrasting biospheric responses at the margins of the growing season, the current extension in the thermal growing season length has not led to a concomitant extension of the period of biospheric carbon uptake.”

Citation: Barichivich, J., K. R. Briffa, T. J. Osborn, T. M. Melvin, and J. Caesar (2012), Thermal growing season and timing of biospheric carbon uptake across the Northern Hemisphere, Global Biogeochem. Cycles, 26, GB4015, doi:10.1029/2012GB004312.


Global warming will be accelerated with reduced aerosol negative forcing

Distributions and climate effects of atmospheric aerosols from the preindustrial era to 2100 along Representative Concentration Pathways (RCPs) simulated using the global aerosol model SPRINTARS – Takemura (2012) [FULL TEXT]

Abstract: “Global distributions and associated climate effects of atmospheric aerosols were simulated using a global aerosol climate model, SPRINTARS, from 1850 to the present day and projected forward to 2100. Aerosol emission inventories used by the Coupled Model Intercomparison Project Phase 5 (CMIP5) were applied to this study. Scenarios based on the Representative Concentration Pathways (RCPs) were used for the future projection. Aerosol loading in the atmosphere has already peaked and is now reducing in Europe and North America. However, in Asia where rapid economic growth is ongoing, aerosol loading is estimated to reach a maximum in the first half of this century. Atmospheric aerosols originating from the burning of biomass have maintained high loadings throughout the 21st century in Africa, according to the RCPs. Evolution of the adjusted forcing by direct and indirect aerosol effects over time generally correspond to the aerosol loading. The probable future pathways of global mean forcing differ based on the aerosol direct effect for different RCPs. Because aerosol forcing will be close to the preindustrial level by the end of the 21st century for all RCPs despite the continuous increases in greenhouse gases, global warming will be accelerated with reduced aerosol negative forcing.”

Citation: Takemura, T.: Distributions and climate effects of atmospheric aerosols from the preindustrial era to 2100 along Representative Concentration Pathways (RCPs) simulated using the global aerosol model SPRINTARS, Atmos. Chem. Phys., 12, 11555-11572, doi:10.5194/acp-12-11555-2012, 2012.


Ocean acidification limits temperature-induced poleward expansion of coral habitats around Japan

Ocean acidification limits temperature-induced poleward expansion of coral habitats around Japan – Yara et al. (2012) [FULL TEXT]

Abstract: “Using results from four coupled global carbon cycle-climate models combined with in situ observations, we estimate the effects of future global warming and ocean acidification on potential habitats for tropical/subtropical and temperate coral communities in the seas around Japan. The suitability of coral habitats is classified on the basis of the currently observed regional ranges for temperature and saturation states with regard to aragonite (Ωarag). We find that, under the “business as usual” SRES A2 scenario, coral habitats are projected to expand northward by several hundred kilometers by the end of this century. At the same time, coral habitats are projected to become sandwiched between regions where the frequency of coral bleaching will increase, and regions where Ωarag will become too low to support sufficiently high calcification rates. As a result, the habitat suitable for tropical/subtropical corals around Japan may be reduced by half by the 2020s to 2030s, and is projected to disappear by the 2030s to 2040s. The habitat suitable for the temperate coral communities is also projected to decrease, although at a less pronounced rate, due to the higher tolerance of temperate corals for lowΩarag. Our study has two important caveats: first, it does not consider the potential adaptation of the coral communities, which would permit them to colonize habitats that are outside their current range. Second, it also does not consider whether or not coral communities can migrate quickly enough to actually occupy newly emerging habitats. As such, our results serve as a baseline for the assessment of the future evolution of coral habitats, but the consideration of important biological and ecological factors and feedbacks will be required to make more accurate projections.”

Citation: Yara, Y., Vogt, M., Fujii, M., Yamano, H., Hauri, C., Steinacher, M., Gruber, N., and Yamanaka, Y.: Ocean acidification limits temperature-induced poleward expansion of coral habitats around Japan, Biogeosciences, 9, 4955-4968, doi:10.5194/bg-9-4955-2012, 2012.


In western North America climate change comes with droughts and declining vegetation

Projected Future Changes in Vegetation in Western North America in the 21st Century – Jiang et al. (2012)

Abstract: “Rapid and broad-scale forest mortality associated with recent droughts, rising temperature, and insect outbreaks has been observed over western North America (NA). Climate models project additional future warming and increasing drought and water stress for this region. To assess future potential changes in vegetation distributions in western NA, the Community Earth System Model (CESM) coupled with its dynamic global vegetation model (DGVM) was used under the future A2 emissions scenario. In order to better span uncertainties in future climate, eight sea surface temperature (SST) projections provided by CMIP3 (phase 3 of the Coupled Model Intercomparison Project) were employed as boundary conditions. There is a broad consensus amongst the simulations, despite differences in the simulated climate trajectories across the ensemble, that needleleaf evergreen tree coverage will decline by approximately 23% (from 45% to 22%) coincident with a 19% (from 14% to 33%) increase in shrubs and grasses by the end of the 21st century in western NA, with most of the change occurring over the latter half of the 21st century. The net impact is a ~ 6 GtC or about 50% decrease in projected ecosystem carbon storage in this region. The findings suggest a potential for a widespread shift from tree-dominated landscapes to shrub and grass-dominated landscapes in western NA due to future warming and consequent increases in water deficits. These results highlight the need for improved process-based understanding of vegetation dynamics, particularly including mortality and the subsequent incorporation of these mechanisms into Earth System Models in order to better quantify the vulnerability of western NA forests under climate change.”

Citation: Xiaoyan Jiang, Sara A. Rauscher, Todd D. Ringler, David M. Lawrence, A. Park Williams, Craig D. Allen, Allison L. Steiner, D. Michael Cai, and Nate G. McDowell, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00430.1 .


Greenland ice sheet mass balance reconstruction (1600-2009) part 1

Greenland ice sheet mass balance reconstruction. Part I: net snow accumulation (1600-2009) – Box et al. (2012)

Abstract: “Ice core data are combined with RACMO2 regional climate model (RCM) output (1958-2010) to develop a reconstruction of the Greenland ice sheet net snow accumulation rate (Ât(G)) spanning years 1600-2009. Regression parameters from RCM output regressed on 86 ice cores are used with available cores in a given year resulting in the reconstructed values. Each core site’s residual variance is used to inversely weight the cores’ respective contributions. The interannual amplitude of the reconstructed accumulation rate is damped by the regressions and is thus calibrated to match that of the RCM data. Uncertainty and significance of changes is measured using statistical models. We find a 12% or 86 Gt y-1 increase in ice sheet accumulation rate from the end of the Little Ice Age in ~1840 to the last decade of the reconstruction. This 1840-1996 trend is 30% higher than that of 1600-2009, suggesting an accelerating accumulation rate. The correlation of Ât(G) with the average surface air temperature in the Northern Hemisphere(SATNHt) remains positive through time, while the correlation of Ât(G) with local near-surface air temperatures or North Atlantic sea surface temperatures is inconsistent, suggesting a hemispheric-scale climate connection. We find an annual sensitivity of Ât(G) to SATNHt of 6.8% K-1 or 51 Gt K-1. The reconstuction, Ât(G), correlates consistently highly with the North Atlantic Oscillation index. Yet, at the 11-year time scale, the sign of this correlation flips four times in the 1870-2005 period.”

Citation: Jason E. Box, Noel Cressie, David H. Bromwich, Ji-Hoon Jung, Michiel van den Broeke, J. H. van Angelen, Richard R. Forster, Clement Miège, Ellen Mosley-Thompson, Bo Vinther, and Joseph R. McConnell, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00373.1.


Closing the global mean sea level rise budget for 20th century

Twentieth-century global-mean sea-level rise: is the whole greater than the sum of the parts? – Gregory et al. (2012)

Abstract: “Confidence in projections of global-mean sea-level rise (GMSLR) depends on an ability to account for GMSLR during the 20th century. There are contributions from ocean thermal expansion, mass loss from glaciers and ice sheets, groundwater extraction and reservoir impoundment. We have made progress towards solving the “enigma” of 20th-century GMSLR—that is, the observed GMSLR has been found to exceed the sum of estimated contributions, especially for the earlier decades. We propose that: thermal expansion simulated by climate models may previously have been underestimated owing to their not including volcanic forcing in their control state; the rate of glacier mass loss was larger than previously estimated, and was not smaller in the first than in the second half of the century; the Greenland ice-sheet could have made a positive contribution throughout the century; groundwater depletion and reservoir impoundment, which are of opposite sign, may have been approximately equal in magnitude. We show that it is possible to reconstruct the timeseries of GMSLR from the quantified contributions, apart from a constant residual term which is small enough to be explained as a long-term contribution from the Antarctic ice-sheet. The reconstructions account for the approximate constancy of the rate of GMSLR during the 20th century, which shows small or no acceleration, despite the increasing anthropogenic forcing. Semi-empirical methods for projecting GMSLR depend on the existence of a relationship between global climate change and the rate of GMSLR, but the implication of our closure of the budget is that such a relationship is weak or absent during the 20th century.”

Citation: J. M. Gregory, N. J. White, J. A. Church, M. F. P. Bierkens, J. E. Box, M. R. van den Broeke, J. G. Cogley, X. Fettweis, E. Hanna, P. Huybrechts, L. F. Konikow, P. W. Leclercq, B. Marzeion, J. Oerlemans, M. E. Tamisiea, Y. Wada, L. M. Wake, and R. S.W. van de Wal, Journal of Climate 2012, doi: http://dx.doi.org/10.1175/JCLI-D-12-00319.1.


Blue mussel species tolerates ocean acidification

Food availability outweighs ocean acidification effects in juvenile Mytilus edulis: laboratory and field experiments – Thomsen et al. (2012)

Abstract: “Ocean acidification is expected to decrease calcification rates of bivalves. Nevertheless in many coastal areas high pCO2 variability is encountered already today. Kiel Fjord (Western Baltic Sea) is a brackish (12-20 g kg-1) and CO2 enriched habitat, but the blue mussel Mytilus edulis dominates the benthic community. In a coupled field and laboratory study we examined the annual pCO2 variability in this habitat and the combined effects of elevated pCO2 and food availability on juvenile M. edulis growth and calcification. In the laboratory experiment, mussel growth and calcification were found to chiefly depend on food supply, with only minor impacts of pCO2 up to 3350 μatm. Kiel Fjord was characterized by strong seasonal pCO2 variability. During summer, maximal pCO2 values of 2500 μatm were observed at the surface and >3000 μatm at the bottom. However, the field growth experiment revealed seven times higher growth and calcification rates of M. edulis at a high pCO2 inner fjord field station (mean pCO2 ca. 1000 μatm) in comparison to a low pCO2 outer fjord station (ca. 600 μatm). In addition, mussels were able to outcompete the barnacle Amphibalanus improvisus at the high pCO2 site. High mussel productivity at the inner fjord site was enabled by higher particulate organic carbon concentrations. Kiel Fjord is highly impacted by eutrophication, which causes bottom water hypoxia and consequently high seawater pCO2. At the same time, elevated nutrient concentrations increase the energy availability for filter feeding organisms such as mussels. Thus M. edulis can dominate over a seemingly more acidification resistant species such as A. improvisus. We conclude that benthic stages of M. edulis tolerate high ambient pCO2 when food supply is abundant and that important habitat characteristics such as species interactions and energy availability need to be considered to predict species vulnerability to ocean acidification.”

Citation: Jörn Thomsen, Isabel Casties, Christian Pansch, Arne Körtzinger, Frank Melzner, Global Change Biology, DOI: 10.1111/gcb.12109.


Climate change is projected to increase fine particulate matter in atmosphere

Impact of 2000–2050 climate change on fine particulate matter (PM2.5) air quality inferred from a multi-model analysis of meteorological modes – Tai et al. (2012) [FULL TEXT]

Abstract: “Studies of the effect of climate change on fine particulate matter (PM2.5 air quality using general circulation models (GCMs) show inconsistent results including in the sign of the effect. This reflects uncertainty in the GCM simulations of the regional meteorological variables affecting PM2.5. Here we use the CMIP3 archive of data from fifteen different IPCC AR4 GCMs to obtain improved statistics of 21st-century trends in the meteorological modes driving PM2.5 variability over the contiguous US. We analyze 1999–2010 observations to identify the dominant meteorological modes driving interannual PM2.5 variability and their synoptic periods T. We find robust correlations (r > 0.5) of annual mean PM2.5 with T, especially in the eastern US where the dominant modes represent frontal passages. The GCMs all have significant skill in reproducing present-day statistics for T and we show that this reflects their ability to simulate atmospheric baroclinicity. We then use the local PM2.5-to-period sensitivity (dPM2.5/dT) from the 1999–2010 observations to project PM2.5 changes from the 2000–2050 changes in T simulated by the 15 GCMs following the SRES A1B greenhouse warming scenario. By weighted-average statistics of GCM results we project a likely 2000–2050 increase of ~ 0.1 μg m−3in annual mean PM2.5 in the eastern US arising from less frequent frontal ventilation, and a likely decrease albeit with greater inter-GCM variability in the Pacific Northwest due to more frequent maritime inflows. Potentially larger regional effects of 2000–2050 climate change on PM2.5 may arise from changes in temperature, biogenic emissions, wildfires, and vegetation, but are still unlikely to affect annual PM2.5 by more than 0.5 μg m−3.”

Citation: Tai, A. P. K., Mickley, L. J., and Jacob, D. J.: Impact of 2000–2050 climate change on fine particulate matter (PM2.5) air quality inferred from a multi-model analysis of meteorological modes, Atmos. Chem. Phys., 12, 11329-11337, doi:10.5194/acp-12-11329-2012, 2012.


Other studies from last week

Predicting long-term carbon mineralization and trace gas production from thawing permafrost of Northeast Siberia – Knoblauch et al. (2012)

Increasing Global Agricultural Production by Reducing Ozone Damages via Methane Emission Controls and Ozone Resistant Cultivar Selection – Avnery et al. (2012)

The Changing Energy Balance of the Polar Regions in a Warmer Climate – Bengtsson et al. (2012)

Changes in surface shortwave solar irradiance from 1993 to 2011 at Thessaloniki (Greece) – Bais et al. (2012)

Climate-associated population declines reverse recovery and threaten future of an iconic high-elevation plant – Krushelnycky et al. (2012)

Proximate weather patterns and spring green-up phenology effect Eurasian beaver (Castor fiber) body mass and reproductive success: The implications of climate change and topography – Campbell et al. (2012)

Inactive period of Western North Pacific Tropical Cyclone Activity in 1998-2011 – Liu & Chan (2012)

Observational evidence for oceanic forcing of atmospheric variability in the Nordic Seas area – Schlichtholz (2012)

Long-term variation of atmospheric methyl iodide and its link to global environmental change – Yokouchi et al. (2012)

Interannual variability of outgoing longwave radiation as observed by AIRS and CERES – Susskind et al. (2012)

Critical assessment of surface incident solar radiation observations collected by SURFRAD, USCRN and AmeriFlux networks from 1995 to 2011 – Wang et al. (2012)

The 2010 spring drought reduced primary productivity in southwestern China – Zhang et al. (2012) [FULL TEXT]

Negative long term effects on harbour porpoises from a large scale offshore wind farm in the Baltic—evidence of slow recovery – Teilmann & Carstensen (2012) [FULL TEXT]

Assessment of the quality of OSIRIS mesospheric temperatures using satellite and ground-based measurements – Sheese et al. (2012) [FULL TEXT]

Anomalously severe cold nights and warm days in northeastern Spain: Their spatial variability, driving forces and future projections – El Kenawy et al. (2012)

Long-term changes in lower tropospheric baseline ozone concentrations at northern mid-latitudes – Parrish et al. (2012) [FULL TEXT]

No statistically significant effect of a short-term decrease in the nucleation rate on atmospheric aerosols – Dunne et al. (2012) [FULL TEXT]

Greenhouse gas policy influences climate via direct effects of land-use change – Jones et al. (2012)

Recent drought events over the central Indian region: Pacific Ocean origin and insights from moisture budgets – Sooraj et al. (2012)

Palaeoenvironmental changes of the last two millennia on the western and northern Svalbard shelf – Jernas et al. (2012)

The sensitivity of stratospheric ozone changes through the 21st century to N2O and CH4 – Revell et al. (2012) [FULL TEXT]

Remote sensing of sea ice: advances during the DAMOCLES project – Heygster et al. (2012) [FULL TEXT]

Relationships between particles, cloud condensation nuclei and cloud droplet activation during the third Pallas Cloud Experiment – Anttila et al. (2012) [FULL TEXT]

Effects of stratospheric sulfate aerosol geo-engineering on cirrus clouds – Kuebbeler et al. (2012)

Modeling shortwave radiative fluxes from satellites – Ma & Pinker (2012)


CLASSIC OF THE WEEK: White (1907)

Permo-Carboniferous Climatic Changes in South America – White (1907) [FULL TEXT]

Abstract: No abstract.

Citation: David White, The Journal of Geology, Vol. 15, No. 7 (Oct. – Nov., 1907) (pp. 615-633).


About this series. When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. Here’s the archive for the research papers of previous weeks. If this sort of thing interests you, be sure to check out A Few Things Illconsidered. They also have a weekly posting containing lots of links to new research and other climate related news.

Posted in Climate science | 1 Comment »

New research from last week 48/2012

Posted by Ari Jokimäki on December 3, 2012

Sometimes in the past western Greenland was warmer than today! There has been increasingly warm summers in Euro-Mediterranean region – is this due to increasing solar radiation observed in Spain? There’s an increasing need of dusting in Tibetan Plateau due to warming, which by the way is proceeding globally just as expected from GHG-cause. We also look at Fijian corals, vegetation response to climate, and an example of climate caused collapse of prehistoric human society. Check out also the 25 other studies if you want to know some other things, such as the impact of precipitation on vehicle speeds on UK motorways, or storm of November 1724.


Peak Holocene warmth was 2-3K warmer than today in western Greenland

Holocene temperature history at the western Greenland Ice Sheet margin reconstructed from lake sediments – Axford et al. (2012)

Highlights: ► This paper presents five Holocene lake records from west Greenland. ► Chironomids provide quantitative estimates of summer air temperature anomalies. ► Peak Holocene warmth occurred from 6 to 4 ka, with temperatures 2–3° warmer than today. ► A transient climate change is recorded at all five study sites ∼4.2 ka. ► The inferred paleotemperature history agrees well with local glacial geologic records.

Abstract: “Predicting the response of the Greenland Ice Sheet to future climate change presents a major challenge to climate science. Paleoclimate data from Greenland can provide empirical constraints on past cryospheric responses to climate change, complementing insights from contemporary observations and from modeling. Here we examine sedimentary records from five lakes near Jakobshavn Isbræ in central West Greenland to investigate the timing and magnitude of major Holocene climate changes, for comparison with glacial geologic reconstructions from the region. A primary objective of this study is to constrain the timing and magnitude of maximum warmth during the early to middle Holocene positive anomaly in summer insolation. Temperature reconstructions from subfossil insect (chironomid) assemblages suggest that summer temperatures were warmer than present by at least 7.1 ka (the beginning of the North Lake record; ka = thousands of years before present), and that the warmest millennia of the Holocene occurred in the study area between 6 and 4 ka. Previous studies in the Jakobshavn region have found that the local Greenland Ice Sheet margin was most retracted behind its present position between 6 and 5 ka, and here we use chironomids to estimate that local summer temperatures were 2–3 °C warmer than present during that time of minimum ice sheet extent. As summer insolation declined through the late Holocene, summer temperatures cooled and the local ice sheet margin expanded. Gradual, insolation-driven millennial-scale temperature trends in the study area were punctuated by several abrupt climate changes, including a major transient event recorded in all five lakes between 4.3 and 3.2 ka, which overlaps in timing with abrupt climate changes previously documented around the North Atlantic region and farther afield at ∼4.2 ka.”

Citation: Yarrow Axford, Shanna Losee, Jason P. Briner, Donna R. Francis, Peter G. Langdon, Ian R. Walker, Quaternary Science Reviews, Volume 59, 3 January 2013, Pages 87–100, http://dx.doi.org/10.1016/j.quascirev.2012.10.024.


Warming seems make Tibetan Plateau dustier

Atmospheric dust from a shallow ice core from Tanggula: implications for drought in the central Tibetan Plateau over the past 155 years – Wu et al. (2012)

Highlights: ► We provide the Tanggula ice core record during 1850–2004 A.D. ► The 1860–1874 and 1930–1954 are two high dust flux periods. ► Dust flux increased since 1960 within warming perspective. ► High dust is correlated with strengthened westerlies over the Tibetan Plateau and low pressure in the source regions. ► Warming seems make Tibetan Plateau dustier.

Abstract: “The dustiness on the remote Tibetan Plateau and its trend within the ongoing global warming perspective are not well understood. In this study, we present the detailed dust history from 1850 to 2004 AD on an annual timescale from a shallow ice core from Tanggula, central Tibetan Plateau. Two periods of strong dustiness, one at the end of the Little Ice Age (1860–1874) and the other during the period 1930–1954, occurred during low oxygen isotope stage, which is correlated with temperature on multi-year and decadal timescales. The extremely high level of dust flux between 1860 and 1874 was unique – this level has not occurred again during the past century, and the 1930s’ dustiness was characterized more by strong wind and dust storms rather than drought, as shown by great grain size but low dust flux. We have used the composite analysis of modern meteorological data to study the possible dustiness mechanism and found that strengthened high-level westerlies over the Tibetan Plateau and intensified low pressure activities in the upward potential source regions, such as Tarim Basin, are the possible causes for high dust flux in Tanggula. Those results have revealed that although the dustiness on the Tibetan Plateau normally occurs in cold conditions, pronounced warming since the 1960s can change the dust pattern and strengthen the dustiness in this remote and high-altitude region, and can thus induce associated environmental issues by creating dustier conditions.”

Citation: Guangjian Wu, Chenglong Zhang, Baiqing Xu, Rui Mao, Daniel Joswiak, Ninglian Wang, Tandong Yao, Quaternary Science Reviews, Volume 59, 3 January 2013, Pages 57–66, http://dx.doi.org/10.1016/j.quascirev.2012.10.003.


Increasing solar radiation in Spain suggests decrease of clouds and/or aerosols

Global and diffuse solar radiation in Spain: Building a homogeneous dataset and assessing their trends – Sanchez-Lorenzo et al. (2012)

Highlights: ► We develop a new dataset of surface solar radiation records in Spain. ► The global and diffuse solar radiation series have been homogenized. ► The global solar radiation shows a significant increase over the 1985-2010 period. ► The diffuse component shows a significant decrease during the same period. ► These results point towards a recent decrease of clouds and/or aerosols.

Abstract: “There is a growing interest in the study of decadal variations in surface solar radiation during the last decades, although the analyses of long-term time series in some areas with major gaps in observations, such as in Spain, is still pending. This work describes for the first time the development of a new dataset of surface solar radiation in Spain based on the longest series with records of global solar radiation (G), most of them starting in the early 1980s. Additional records of diffuse solar radiation (D), which is a component of G much less studied due to the general scarcity of long-term series, are available for some of these series. Particular emphasis is placed upon the homogenization of this data set in order to ensure the reliability of the trends, which can be affected by non-natural factors such as relocations or changes of instruments. The mean annual G series over Spain shows a tendency to increase during the 1985-2010 period, with a significant linear trend of + 3.9 Wm- 2 per decade. Similar significant increases are observed in the mean seasonal series, with the highest rate of change during summer (+ 6.5 Wm- 2 per decade) and secondly in autumn (+ 4.1 W m- 2 per decade) and spring (+ 3.2 Wm- 2 per decade). These results are in line with the widespread increase of G, also known as brightening period, reported at many worldwide observation sites. Furthermore, the annual mean D series starts without relevant variations during the second half of the 1980s, but it is disturbed by a strong increase in 1991 and 1992, which might reflect the signal of the Pinatubo volcanic eruption. Afterwards, the mean series shows a tendency to decrease up to the mid-2000s, with a significant linear trend of -2.1 Wm- 2 per decade during the 1985-2010 period. All these results point towards a diminution of clouds and/or aerosols over the area.”

Citation: A. Sanchez-Lorenzo, J. Calbó, M. Wild, Global and Planetary Change, http://dx.doi.org/10.1016/j.gloplacha.2012.11.010.


Increasingly warm summers in the Euro–Mediterranean zone

Increasingly warm summers in the Euro–Mediterranean zone: mean temperatures and extremes – Simolo et al. (2012)

Abstract: “The recent increase in European temperatures led to a strong enhancement in the occurrence of extremely warm events, with relevant consequences for environment and everyday life. Here, we investigate the evolution of very intense warm and cold events in a south-western European zone during 1961–2007 at a seasonal level. Special attention is given to summertime when warming is the most pronounced. Using a previously developed theoretical model, we discuss how the average properties and long-term trends observed in probability density functions of daily temperatures can explain changes in the frequency of severe, isolated events. In this perspective, the recent intensification of extremely warm events, especially experienced by the Mediterranean zone, is proved to be well consistent with a pure shift of seasonal mean temperatures. On the other hand, any change in the second and higher distributional moments of daily temperatures is ruled out by the data, whereas the average values of these properties, that is, variability and asymmetry, do play a role by shaping the temporal behavior of very intense events.”

Citation: Claudia Simolo, Michele Brunetti, Maurizio Maugeri, Teresa Nanni, Regional Environmental Change, November 2012, DOI: 10.1007/s10113-012-0373-7.


Atmospheric carbon-13 Suess Effect shows in Fijian corals

The Suess effect in Fiji coral δ13C and its potential as a tracer of anthropogenic CO2 uptake – Dassié et al. (2012)

Highlights: ► Long-term decreasing trend in coral δ13C is due to the atmospheric 13C Suess Effect. ► Fiji Porites corals growing at deeper water depths have lower mean δ13C. ► Fiji Porites corals growing at deeper water depths have lower skeletal extension rate rate. ► The growth of corals into shallower water with time dampens the δ13C trend. ► The trend in coral δ13C lags the trend in atmospheric CO2 δ13C by ~ 10 years.

Abstract: “In the context of increasing anthropogenic CO2 emissions, determing the rate of oceanic CO2 uptake is of high interest. Centennial-scale changes in δ13C of the surface water dissolved inorganic carbon (DIC) reservoir have been shown to be influenced by the carbon isotopic composition of atmospheric CO2. However, the avalability of direct oceanic δ13C measurments is limited and methods for reconstructing past δ13C variability of the oceanic DIC are needed. Geochemical reconstructions of DIC variability can help in understanding how the ocean has reacted to historical changes in the carbon cycle. This study explores the potential of using temporal variations in δ13C measured in five Fijian Porites corals for reconstructing oceanic δ13C variability. A centennial-scale decreasing δ13C trend is observed in these Fiji corals. Other studies have linked similar decreasing δ13C trends to anthropogenic changes in the atmospheric carbon reservoir (the “13C Suess Effect”). In the Fiji corals, whereas we conclude that solar irradiance is the factor influencing the δ13C cycle on seasonal scale, it is not responsible for the centennial scale δ13C decreasing trend. In addition, variations in skeletal extension rate are not found to account for centennial-scale δ13C variability in these corals. Rather, we found that water depth at which a Fijian Porites colony calcifies influences both δ13C and extension rate mean values. The water depth-δ13C relationship induces a dampening effect on the centennial-scale decreasing δ13C trend. We removed this water depth effect from the δ13C composite, resulting in a truer representation of δ13C variability of the Fiji surface water DIC (δ13C Fiji-DIC). The centennial trend in this Fiji coral composite δ13C Fiji-DIC time-serie, shares similarities with atmospheric δ13CCO2, implicating the 13C Suess effect as the source of the this coral δ13C trend. Additionaly, our study found that the δ13C variability between the atmosphere and the ocean in this region is not synchronous; the coral δ13C response is delayed by ~ 10 years. This agrees with the model of the isotopic disequilibrium between atmospheric δ13CCO2 and oceanic surface water DIC.”

Citation: Emilie P. Dassié, Gavin M. Lemley, Braddock K. Linsley, Palaeogeography, Palaeoclimatology, Palaeoecology, http://dx.doi.org/10.1016/j.palaeo.2012.11.012.


Phenology is important factor in vegetation feedbacks to climate system

Climate change, phenology, and phenological control of vegetation feedbacks to the climate system – Richardson et al. (2012)

Highlights: ► The sensitivity of vegetation phenology to climate change varies among biomes. ► Key weaknesses in our current understanding of phenology drivers are identified. ► Phenology controls many feedbacks of vegetation to the climate system. ► The size and seasonality of these feedbacks will shift as phenology shifts. ► Models that couple the land surface to the climate system need better phenology.

Abstract: “Vegetation phenology is highly sensitive to climate change. Phenology also controls many feedbacks of vegetation to the climate system by influencing the seasonality of albedo, surface roughness length, canopy conductance, and fluxes of water, energy, CO2 and biogenic volatile organic compounds. In this review, we first discuss the environmental drivers of phenology, and the impacts of climate change on phenology, in different biomes. We then examine the vegetation-climate feedbacks that are mediated by phenology, and assess the potential impact on these feedbacks of shifts in phenology driven by climate change. We finish with an overview of phenological modeling and we suggest ways in which models might be improved using existing data sets. Several key weaknesses in our current understanding emerge from this analysis. First, we need a better understanding of the drivers of phenology, particularly in under-studied biomes (e.g. tropical forests). We do not have a mechanistic understanding of the role of photoperiod, even in well-studied biomes. In all biomes, the factors controlling senescence and dormancy are not well-documented. Second, for the most part (i.e. with the exception of phenology impacts on CO2 exchange) we have only a qualitative understanding of the feedbacks between vegetation and climate that are mediated by phenology. We need to quantify the magnitude of these feedbacks, and ensure that they are accurately reproduced by models. Third, we need to work towards a new understanding of phenological processes that enables progress beyond the modeling paradigms currently in use. Accurate representation of phenological processes in models that couple the land surface to the climate system is particularly important, especially when such models are being used to predict future climate.”

Citation: Andrew D. Richardson, Trevor F. Keenan, Mirco Migliavacca, Youngryel Ryu, c, Oliver Sonnentag, Michael Toomey, Agricultural and Forest Meteorology, Volume 169, 15 February 2013, Pages 156–173, http://dx.doi.org/10.1016/j.agrformet.2012.09.012.


ENSO mega-drought triggered collapse of prehistoric Aboriginal society in northwest Australia

Evidence of ENSO mega-drought triggered collapse of prehistory Aboriginal society in northwest Australia – McGowan et al. (2012)

Highlights: •Millennial scale failure of the Australian monsoon, •ENSO mega-drought, •Climate forced rapid change of Aboriginal cultures.

Abstract: “The Kimberley region of northwest Australia contains one of the World’s largest collections of rock art characterised by two distinct art forms; the fine featured anthropomorphic figures of the Gwion Gwion or Bradshaw paintings, and broad stroke Wandjina figures. Luminescence dating of mud wasp nests overlying Gwion Gwion paintings has confirmed an age of at least 17,000 yrs B.P. with the most recent dates for these paintings from around the mid-Holocene (5000 to 7000 yrs B.P.). Radiocarbon dating indicates that the Wandjina rock art then emerged around 3800 to 4000 yrs B.P. following a hiatus of at least 1200 yrs. Here we show that a mid-Holocene ENSO forced collapse of the Australian summer monsoon and ensuing mega-drought spanning approximately 1500 yrs was the likely catalyst of this change in rock art. The severity of the drought we believe was enhanced through positive feedbacks triggered by change in land surface condition and increased aerosol loading of the atmosphere leading to a weakening or failure of monsoon rains. This confirms that pre-historic aboriginal cultures experienced catastrophic upheaval due to rapid natural climate variability and that current abundant seasonal water supplies may fail again if significant change in ENSO occurs.”

Citation: McGowan, H., S. Marx, P. Moss, and A. Hammond (2012), Evidence of ENSO mega-drought triggered collapse of prehistory Aboriginal society in northwest Australia, Geophys. Res. Lett., 39, L22702, doi:10.1029/2012GL053916.


Global temperature continues to increase in good agreement with best estimates of IPCC

Comparing climate projections to observations up to 2011 – Rahmstorf et al. (2012) [FULL TEXT]

Abstract: “We analyse global temperature and sea-level data for the past few decades and compare them to projections published in the third and fourth assessment reports of the Intergovernmental Panel on Climate Change (IPCC). The results show that global temperature continues to increase in good agreement with the best estimates of the IPCC, especially if we account for the effects of short-term variability due to the El Niño/Southern Oscillation, volcanic activity and solar variability. The rate of sea-level rise of the past few decades, on the other hand, is greater than projected by the IPCC models. This suggests that IPCC sea-level projections for the future may also be biased low.”

Citation: Stefan Rahmstorf et al 2012 Environ. Res. Lett. 7 044035 doi:10.1088/1748-9326/7/4/044035.


Climate warming and vegetation response after Heinrich event 1 in southern Europe

Climate warming and vegetation response after Heinrich event 1 (16 700–16 000 cal yr BP) in Europe south of the Alps – Samartin et al. (2012) [FULL TEXT]

Abstract: “Chironomids preserved in a sediment core from Lago di Origlio (416 m a.s.l.), a lake in the foreland of the Southern Swiss Alps, allowed quantitative reconstruction of Late Glacial and Early Holocene summer temperatures using a combined Swiss–Norwegian temperature inference model based on chironomid assemblages from 274 lakes. We reconstruct July air temperatures of ca. 10 °C between 17 300 and 16 000 cal yr BP, a rather abrupt warming to ca. 12.0 °C at ca. 16 500–16 000 cal yr BP, and a strong temperature increase at the transition to the Bølling/Allerød interstadial with average temperatures of about 14 °C. During the Younger Dryas and earliest Holocene similar temperatures are reconstructed as for the interstadial. The rather abrupt warming at 16 500–16 000 cal yr BP is consistent with sea-surface temperature as well as speleothem records, which indicate a warming after the end of Heinrich event 1 (sensu stricto) and before the Bølling/Allerød interstadial in southern Europe and the Mediterranean Sea. Pollen records from Origlio and other sites in southern Switzerland and northern Italy indicate an early reforestation of the lowlands 2000–1500 yr prior to the large-scale afforestation of Central Europe at the onset of the Bølling/Allerød period at ca. 14 700–14 600 cal yr BP. Our results suggest that these early afforestation processes in the formerly glaciated areas of northern Italy and southern Switzerland have been promoted by increasing temperatures.”

Citation: Samartin, S., Heiri, O., Lotter, A. F., and Tinner, W.: Climate warming and vegetation response after Heinrich event 1 (16 700–16 000 cal yr BP) in Europe south of the Alps, Clim. Past, 8, 1913-1927, doi:10.5194/cp-8-1913-2012, 2012.


Other studies from last week

XCO2-measurements with a tabletop FTS using solar absorption spectroscopy – Gisi et al. (2012) [FULL TEXT]

Feedback attribution of the El Niño–Southern Oscillation–related atmospheric and surface temperature anomalies – Park et al. (2012)

Angular anisotropy of satellite observations of land surface temperature – Vinnikov et al. (2012)

Investigating the impact of precipitation on vehicle speeds on UK motorways – Hooper et al. (2012)

Last Glacial warm events on Mount Hermon: the southern extension of the Alpine karst range of the east Mediterranean – Ayalon et al. (2012)

Interacting effects of ocean acidification and warming on growth and DMS-production in the haptophyte coccolithophore Emiliania huxleyi – Arnold et al. (2012)

Modelling distribution in European stream macroinvertebrates under future climates – Domisch et al. (2012)

An analysis of tropical cyclones impacting the Southeast United States from a regional reanalysis – LaRow (2012)

Modeling monthly mean air temperature for Brazil – Alvares et al. (2012)

The meso-scale drivers of temperature extremes in high-latitude Fennoscandia – Aalto et al. (2012)

The first meteorological measurements in the Iberian Peninsula: evaluating the storm of November 1724 – Domínguez-Castro et al. (2012)

Reconstruction of remote climate change from borehole temperature measurement in the eastern part of Morocco – Barkaoui et al. (2012)

Future projections and uncertainty assessment of extreme rainfall intensity in the United States from an ensemble of climate models – Zhu et al. (2012)

Variation in the size structure of corals is related to environmental extremes in the Persian Gulf – Bauman et al. (2012)

Impact of Anthropogenic Absorbing Aerosols on Clouds and Precipitation: A Review of Recent Progresses – Wang (2012)

The determination of permafrost thawing trends from long-term streamflow measurements with an application in eastern Siberia – Brutsaert & Hiyama (2012)

Climate Changes Influence Free-Living Stages Of Soil-Transmitted Parasites Of European Rabbits – Hernandez et al. (2012)

Time-specific black mudstones and global hyperwarming on the Cambrian–Ordovician slope and shelf of the Laurentia palaeocontinent – Landing (2012)

Spatial Decomposition of Climate Feedbacks in the Community Earth System Model – Gettelman et al. (2012)

Transport of black carbon to polar regions: Sensitivity and forcing by black carbon – Zhou et al. (2012)

Response of air stagnation frequency to anthropogenically enhanced radiative forcing – Horton et al. (2012) [FULL TEXT]

Late Holocene air temperature variability reconstructed from the sediments of Laguna Escondida, Patagonia, Chile (45°30′S) – Elbert et al. (2012)

500 years of regional forest growth variability and links to climatic extreme events in Europe – Babst et al. (2012) [FULL TEXT]

Shale gas production: potential versus actual greenhouse gas emissions – O’Sullivan & Paltsev (2012) [FULL TEXT]

Phytoplankton distribution in unusually low sea ice cover over the Pacific Arctic – Coupel et al. (2012) [FULL TEXT]


CLASSIC OF THE WEEK: Barker (1800)

Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon, in Rutland, for the Year 1798 – Barker (1800) [FULL TEXT]

Abstract: No abstract. This is the last of Thomas Barker’s annual climate reports. He made continuous weather observations through many decades in 18th century and reported about them annually in Royal Society’s Philosophical Transactions.

Citation: Thomas Barker, Esq., Phil. Trans. R. Soc. Lond. January 1, 1800 90 46-48; doi:10.1098/rstl.1800.0004.


About this series. When each paper is published, it is notified in AGW Observer Facebook page and Twitter page. Here’s the archive for the research papers of previous weeks. If this sort of thing interests you, be sure to check out A Few Things Illconsidered. They also have a weekly posting containing lots of links to new research and other climate related news.

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