Why extreme weather ‘stalls’ in place
Scientists say they have established why vast swathes of the Northern Hemisphere were besieged by extreme heat waves and prolonged drought over the summer—and warn that these “extreme extremes” are only going to get worse. Large areas of Europe, North America, and Asia endured record temperatures in July and August, with wildfires breaking out as far north as the Arctic Circle. Researchers examined the links between this summer’s weather and Arctic warming—where climate change is causing temperatures to rise between two and four times faster than the global average. They concluded that the narrowing temperature difference between the Arctic and the equator is preventing planetary winds from building up enough energy to push high and low pressure systems around. “The weather in a given region gets stuck,” co-author Hans Joachim Schellnhuber of the Potsdam Institute for Climate Impact Research tells The Independent (U.K.). “Rains can grow into floods, sunny days into heat waves, and tinder-dry conditions into wildfires.” Another prominent example of this “stalling” phenomenon was last year’s Hurricane Harvey, which dumped record volumes of water on Texas after getting “stuck” on the coast and drawing up massive amounts of moisture from the sea. The researchers warn that stalling weather patterns could imperil food production in Europe, Russia, and the U.S.