Human-caused global warming has made severe droughts like the ones this summer in Europe, North America and China at least 20 times as likely to occur as they would have been more than a century ago, scientists said Wednesday. It’s the latest evidence of how climate change caused by the burning of fossil fuels is imperiling food, water and electricity supplies around the world.

The main driver of this year’s droughts was searing heat throughout much of the Northern Hemisphere, the researchers reported in a new study. Such high average temperatures, over such a large area, would have been "virtually impossible” without the influence of greenhouse gas emissions, the scientists said.

Across the Northern Hemisphere north of the tropics, soil conditions as parched as they were this summer now have a roughly 1-in-20 chance of occurring each year, the scientists found. Global warming increased this likelihood, they said, but cautioned that because of the challenges involved in estimating soil moisture at a global scale, the exact size of the increase had a wide possible range.