European Heatwave Exacerbated by Summer Arctic Changes

Since 2010, European heatwaves have dramatically escalated in both duration and severity. The cumulative intensity of European heatwaves has surged by over 50% in the recent decade. Recent studies have reported accelerating Arctic warming and associated mid-latitude circulation changes. However, its summer impacts remain uncertain. Here we provide evidence that the recent summer changes in the Arctic play a critical role in the escalation of European heatwaves. The Arctic has experienced unprecedented regional changes with substantial sea-ice loss since 2010. The Barents-Kara Seas have warmed by 2.3 °C per decade, while western Greenland has cooled by 0.6 °C per decade. The temperature changes in these two regions influenced European weather through two different pathways: 1) Barents-Kara Sea warming weakened daily weather activities over western Eurasia, thereby promoting persistently hot weather; 2) Greenland cooling shifted the North Atlantic jet stream, which allowed easy invasion of warm flows from the subtropics and Sahara. These pathways have intensified concurrently since 2010, which likely exacerbates heatwave risks in Europe.