Cold winters in North America and East Asia are both linked to Arctic warming, but each is associated with a distinct warming pattern, according to a study published online in Nature Geoscience. The results suggest that the rapid warming of the Arctic region in recent years has favoured the frequent occurrence of unusually severe winters in these regions.
Sea-ice loss in the Barents-Kara Sea in autumn has been suggested to influence Northern Hemisphere atmospheric circulation in a way that favours stagnant cold winter weather over the mid-latitude continents. However, this idea is controversial, as these mechanisms are not yet well understood.
Jee-Hoon Jeong and colleagues identify the two strongest spatial patterns of Arctic warming that occur independently of each other in observation-based data that cover the period 1979 to 2014. They find that unusual warmth in the Arctic Barents-Kara Sea precedes severe winter weather in East Asia by about 15 days, whereas an independent pattern of warm temperatures in the East Siberian-Chukchi Sea, further east in the Arctic Ocean, often occurs about 5 days before cold spells in Canada and the US.
The researchers also use climate model simulations to identify the specific changes in the layout of high- and low-pressure systems in the atmosphere that link Arctic warming to cold mid-latitudes, and conclude that understanding the regional distribution of warming in the Arctic may help with assessing the risks of extremely cold winters in North America and East Asia.