Reconciling two approaches to attribution of the 2010 Russian heat wave

Abstract

In the summer 2010 Western Russia was hit by an extraordinary heat wave, with the region experiencing by far the warmest July since records began. Whether and to what extent this event is attributable to anthropogenic climate change is controversial. Dole et al. (2011) report the 2010 Russian heat wave was “mainly natural in origin” whereas Rahmstorf and Coumou (2011) write that with a probability of 80% “the 2010 July heat record would not have occurred” without the large‐scale climate warming since 1980, most of which has been attributed to the anthropogenic increase in greenhouse gas concentrations. The latter explicitly state that their results “contradict those of Dole et al. (2011).” Here we use the results from a large ensemble simulation experiment with an atmospheric general circulation model to show that there is no substantive contradiction between these two papers, in that the same event can be both mostly internally‐generated in terms of magnitude and mostly externally‐driven in terms of occurrence‐probability. The difference in conclusion between these two papers illustrates the importance of specifying precisely what question is being asked in addressing the issue of attribution of individual weather events to external drivers of climate.

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

“…The impacts of temperature extremes have highlighted the urgency of improved understanding of their physical causes and to what extent they are a manifestation of a warming world (e.g., Dole et al 2011;Trenberth and Fasullo 2012;Otto et al 2012;Christidis et al 2014;Perkins 2015). A number of studies have investigated the factors contributing to such extreme events (Schär et al 2004;Otto et al 2012;Hanlon et al 2013;Christidis et al 2014) and how extremes will change in response to anthropogenic forcings (Kim et al 2013;Lindvall and Svensson 2014;Cattiaux et al 2015;Vavrus et al 2015).…”

“…A number of studies have investigated the factors contributing to such extreme events (Schär et al 2004;Otto et al 2012;Hanlon et al 2013;Christidis et al 2014) and how extremes will change in response to anthropogenic forcings (Kim et al 2013;Lindvall and Svensson 2014;Cattiaux et al 2015;Vavrus et al 2015). These factors include the role of soil-atmosphere feedbacks during the hot summers.…”

Warm spells in Northern Europe in relation to atmospheric circulation

“…Previous studies have been mainly limited to the analysis of single heat waves from 2003 to 2006 that inflicted damage in Southern and Western Europe (Beniston 2004;Vandentorren et al 2004) and of the 2010 heat wave in Eastern Europe (Dole et al 2011;Grumm 2011;Otto et al 2012). Because of the substantial influence of warm spells on human health, the results of this study are likely interesting to a wide and diverse audience.…”

Regional climate engineering by radiation management: Prerequisites and prospects

“…This can be based on a large model ensemble [Massey et al, 2015]. In attributing a climate event to anthropogenic activity, it is important to assess both the likelihood and the magnitude [Otto et al, 2012]. Detection and attribution for RM targeting continental heat waves may be more feasible than for other weather conditions.…”