Last October, we highlighted a study by Rahmstorf and Coumou which, through utilizing a Monte Carlo simulation, found that the Russian heat wave of 2010 had an 80% likelihood of being attributed to a long-term climatic warming trend. The finding was significant because it seemed to contradict an earlier study by Dole et al, highlighted by Andrew Revkin of the New York Times, that did not find evidence of a climate change link, and thus asserted that the link did not exist. This was, in the words of Rahmstorf and Coumou, a case of confusing “an absence of evidence” with “evidence of absence.”
Now, a new multi-model study by Allen et al, which got some coverage at the Guardian last month, seems to have reconciled the two camps, showing 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.” In other words, while it doesn’t necessarily take climate change to produce a heat wave of that scale, it is highly unlikely that the heat wave would have occurred without it. The two studies were simply asking different questions. Not surprisingly, their answers were different, and it shouldn’t surprise us that those answers can peacefully (and intellectually) coexist!
However, beyond this virtuous and rare act of evidence-based academic diplomacy, the study by Allen and his colleagues ultimately confirms the essential finding of Rahmstorf and Coumou, stating that the “Russian heat wave 2010 [is] likely attributable to anthropogenic climate change.”
Given that findings from multi-climate model simulations like this one are inherently sturdier than those utilizing single models, this is strong evidence indeed.