AGW Observer

Observations of anthropogenic global warming

New research – temperature (October 18, 2016)

Posted by Ari Jokimäki on October 18, 2016

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


Comparing tropospheric warming in climate models and satellite data (Santer et al. 2016)

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

Deep and Abyssal Ocean Warming from 35 years of Repeat Hydrography (Desbruyères et al. 2016)

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

The contribution of greenhouse gases to the recent slowdown in global-mean temperature trends (Checa-Garcia et al. 2016)

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

The Stancari air thermometer and the 1715–1737 record in Bologna, Italy (Camuffo et al. 2016)

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

Twenty-five winters of unexpected Eurasian cooling unlikely due to Arctic sea-ice loss (McCusker et al. 2016)

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

Other papers

New method of estimating temperatures near the mesopause region using meteor radar observations (Lee et al. 2016)

Estimated influence of urbanization on surface warming in Eastern China using time-varying land use data (Liao et al. 2016)

The influence of winter and summer atmospheric circulation on the variability of temperature and sea ice around Greenland (Ogi et al. 2016)

A cold and fresh ocean surface in the Nordic Seas during MIS 11: Significance for the future ocean (Kandiano et al. 2016)

Observed and projected sea surface temperature seasonal changes in the Western English Channel from satellite data and CMIP5 multi-model ensemble (L’Hévéder et al. 2016)

Historical ocean reanalyses (1900–2010) using different data assimilation strategies (Yang et al. 2016)

Analysis of the warmest Arctic winter, 2015-2016 (Cullather et al. 2016)

The influence of synoptic circulations and local processes on temperature anomalies at three French observatories (Dione et al. 2016)

Ocean atmosphere thermal decoupling in the eastern equatorial Indian ocean (Joseph et al. 2016)

Changes of the time-varying percentiles of daily extreme temperature in China (Li et al. 2016)

High atmospheric horizontal resolution eliminates the wind-driven coastal warm bias in the southeastern tropical Atlantic (Milinski et al. 2016)

Effects of Natural Variability of Seawater Temperature, Time Series Length, Decadal Trend and Instrument Precision on the Ability to Detect Temperature Trends (Schlegel & Smit, 2016)

Interhemispheric SST gradient trends in the Indian Ocean prior to and during the recent global warming hiatus (Dong & McPhaden, 2016)

Temperature and precipitation extremes in century-long gridded observations, reanalyses, and atmospheric model simulations (Donat et al. 2016)

Atmospheric structure favoring high sea surface temperatures in the western equatorial Pacific (Wirasatriya et al. 2016)

Spatial and temporal changes in daily temperature extremes in China during 1960–2011 (Shen et al. 2016)

Disaggregation of Remotely Sensed Land Surface Temperature: A New Dynamic Methodology (Zhan et al. 2016)

Impact of high-resolution sea surface temperature and urban data on estimations of surface air temperature in a regional climate (Adachi et al. 2016)

Trends of urban surface temperature and heat island characteristics in the Mediterranean (Benas et al. 2016)

Impacts of urbanization on summer climate in China: An assessment with coupled land-atmospheric modeling (Cao et al. 2016)

The impact of climatic and non-climatic factors on land surface temperature in southwestern Romania (Roşca et al. 2016)

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