Global warming has doubled the chances of a heat wave like that one that hit Europe in August 2003, according to new and unprecedented calculations just published in the journal Nature. That was the heat wave that triggered thousands of extra deaths and caused forest fires that resulted in billions of dollars worth of damage–the hottest summer in Europe in 500 years.

Although no specific weather event can be attributed to climate change, statistically heat waves are more likely in a globally warming world. This study is the first to estimate how much human activity has increased the risk of a specific weather event. It’s scientific proof that the world’s (and, in particular, as the largest greenhouse gas polluter, the U.S.’s) failure to address the climate change issue has real, tangible effects on people’s lives.