Europe is ten times more likely than it was earlier this century to have an extremely hot summer due to human-induced climate change, reports a paper published online in Nature Climate Change.
A previous study found that human activity had at least doubled the probability of a European summer heatwave, such as the one experienced in 2003. Using updated summer temperature observations and climate model results, Nikolaos Christidis and colleagues investigated how humans are influencing the probability of extreme heatwaves in Europe. The authors compared the decades 1990-1999 and 2003-2012 and found that very hot summers (where temperatures were 1.6 degrees Celsius higher the historical average temperature) are now likely to occur every five years, compared to every 52 years for the earlier period.
The 2003 heat wave was 2.3 degrees Celsius above the 1961-1990 average summer temperature. Christidis and colleagues show that changes in the last decade have increased the chances of a very hot summer with a temperature increase equivalent to the 2003 heatwave from less than one every 1000 years to approximately one every 127 years.
As summer temperatures continue to increase, so will the likelihood of extremely hot summers. The 2003 heat wave resulted in a death toll of tens of thousands, therefore the authors advise that society act now to adapt to the predicted higher temperatures.