Two distinct influences of Arctic warming on cold winters over North America and

Arctic warming has sparked a growing interest because of its possible impacts on mid-latitude climate1–5. A number of unusually harsh cold winters have occurred in many parts of East Asia and North America in the past few years2,6,7, and observational and modelling studies have suggested that atmospheric variability linked to Arctic warming might have played a central role1,3,4,8–11. Here we identify two distinct influences of Arctic warming which may lead to cold winters over East Asia or North America, based on observational analyses and extensive climate model results. We find that severewinters across East Asia are associatedwith anomalous warmth in the Barents–Kara Sea region, whereas severe winters over North America are related to anomalous warmth in theEast Siberian–Chukchi Sea region. Each regionalwarming over theArcticOcean is accompanied by the local developmen