Nonlinear changes in cold spell and heat wave arising from Arctic sea-ice loss

Whether Arctic sea-ice loss has significant impacts on climate extremes in mid- and high-latitudes remains uncertain. Here we show the full response of cold and warm extremes under two Arctic sea-ice loss scenarios utilizing a coupled global climate model that permits the air-sea coupling. Our results show that the amount of Arctic sea-ice loss determines the spatial extent and magnitude of the weakening of atmospheric circulation in mid- and high-latitudes of the northern hemisphere, leading to nonlinear changes in cold and warm extremes. A relatively localized and moderate weakening of atmospheric circulation induced by the projected sea-ice loss in the next two decades would contribute to less winter cold extremes over the Northern Hemispheric continents. The risks of winter cold spells would be dramatically reduced as the amount of sea-ice loss is increased to the ice-free state. In contrast, as sea-ice loss increases, the continental regions would have increased risk of heat waves over all mid- and high-latitudes.