How declining aerosols and rising greenhouse gases forced rapid warming in Europe since the 1980s

Abstract

[1] Mainland Europe's temperature rise of about 1°C since the 1980s is considerably larger than expected from anthropogenic greenhouse warming. Here we analyse shortwave and longwave surface forcings measured in Switzerland and Northern Germany and relate them to humidity-and temperature increases through the radiation-and energy budget. Shortwave climate forcing from direct aerosol effects is found to be much larger than indirect aerosol cloud forcing, and the total shortwave forcing, that is related to the observed 60% aerosol decline, is two to three times larger than the longwave forcing from rising anthropogenic greenhouse gases. Almost tree quarters of all the shortwave and longwave forcing energy goes into the turbulent fluxes, which increases atmospheric humidity and hence the longwave forcing by water vapour feedback. With anthropogenic aerosols now reaching low and stable values in Europe, solar forcing will subside and future temperature will mainly rise due to anthropogenic greenhouse gas warming. Citation: Philipona, R., K. Behrens, and C. Ruckstuhl

Understanding the rapid summer warming and changes in temperature extremes since the mid-1990s over Western Europe

“…1a). The change in SAT during the recent 16 years (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011) relative to the early period 1964-1993 ranges from 0.93 to 1.10 °C from four data sets, consistent with previous studies (Ruckstuhl et al 2008;Philipona et al 2009;van Oldenborgh et al 2009). The rapid summer mean warming over Western Europe was also accompanied by changes in temperature extremes.…”

“…Understanding the nature and drivers of this variability is an essential step in developing robust climate predictions and risk assessments. In the last few decades, Europe has warmed not only faster than the global average, but also faster than expected from anthropogenic greenhouse gas increases (Ruckstuhl et al 2008;Philipona et al 2009;van Oldenborgh et al 2009). With the warming, Europe experienced record-breaking heat waves and extreme temperatures that imposed disastrous impacts on individuals, and society (Stott et al 2004;Fischer and Schär 2010;Barriopedro et al 2011;Christidis et al 2011Christidis et al , 2012Hegerl et al 2011;Rahmstorf and Coumou 2011;Hoerling et al 2012;Schubert et al Abstract Analysis of observations indicates that there was a rapid increase in summer (June-August) mean surface air temperature (SAT) since the mid-1990s over Western Europe.…”

Aerosol emissions and dimming/brightening in Europe: Sensitivity studies with ECHAM5-HAM

“…At least as important are changes in the prescribed SSTs, which, however, may encapsulate changes do to aerosols (see section 3.4). Based on observational data, Philipona et al [2009] arrive at similar conclusions. Looking at model results for BC, Jones et al [2011] also caution that factors other than aerosol induced changes in SSR may be important for the explanation of observed recent surface temperature changes.…”

“…[5] Changes in SSR may have an impact on surface temperature [Stanhill, 1995;Qian and Giorgi, 2000;Liepert, 2002;Menon et al, 2002;Ramanathan et al, 2005;Wild et al, 2007;Ruckstuhl et al, 2008;Philipona et al, 2009] and the hydrological cycle [Ramanathan et al, 2001;Ohmura and Wild, 2002;Menon, 2004;Liepert et al, 2004;Takemura et al, 2005;Huang et al, 2007;Wild et al, 2008]. The relative importance of SSR changes for surface temperatures in comparison to other factors, like greenhouse gas warming, is currently debated Zhou et al, 2010;Jones et al, 2011].…”

Aerosol trends as a potential driver of regional climate in the central United States: evidence from observations

“…Kumar et al (2013) found that among 22 climate models, those thatand inferred that improved air quality has led to a strong increase in JJA SWdn there. The Eshel (2016) result is similar to European studies that have tied aerosol reductions to enhanced SWdn (Philipona et al, 2009;Ruckstuhl et al, 2008). Tosca et al (2017) compared the observed +0.54 ± 0.52 K decade −1 summertime temperature trend in the southeast US to the −0.05 decade −1 satellite retrieved AOD trend.…”