The disruptions to everyday life have been far-reaching and devastating. In California, firefighters are racing to control what has become the largest fire in state history. Harvests of staple grains like wheat and corn are expected to dip this year, in some cases sharply, in countries as different as Sweden and El Salvador. In Europe, nuclear power plants have had to shut down because the river water that cools the reactors was too warm. Heat waves on four continents have brought electricity grids crashing.
And dozens of heat-related deaths in Japan this summer offered a foretaste of what researchers warn could be big increases in mortality from extreme heat. A study last month in the journal PLOS Medicine projected a fivefold rise for the United States by 2080. The outlook for less wealthy countries is worse; for the Philippines, researchers forecast 12 times more deaths.
Globally, this is shaping up to be the fourth-hottest year on record. The only years hotter were the three previous ones.