Spring–Summer Barents Sea Ice Loss Intensifies the Synchronicity of Recent Extreme Heatwaves in Europe and East Asia

Abstract Synchronous extreme heatwaves across Eurasia have become more frequent in recent decades, posing severe risks to ecosystems, society, and human health. Meanwhile, rapid Arctic Sea ice loss due to Arctic amplification has emerged as a crucial driver of extreme weather and climate events. However, its specific contribution to Eurasian synchronous heatwaves remains poorly understood. Using climate networks, atmospheric dynamic diagnostics, and numerical experiments, we revealed an interdecadal increase in the interannual relationship between Barents Sea ice and Europe‐East Asian synchronous heatwaves after 2000. During 2000–2022, the persistent sea ice loss in the northern Barents Sea from late spring to summer, combined with strong land‐atmosphere feedback over northwestern Europe, triggers and sustains a northwestern European anticyclone. This anticyclone disturbance, positioned north of the Eurasian subtropical jet, excites a northwest‐southeastward propagating Rossby wave train in summer. Thus, another anticyclone is induced in the north of Tibetan Plateau. Together, these two anticyclones provide favorable atmospheric conditions for the occurrence of Europe‐East Asian synchronous heatwaves. During 1979–1999, however, sea ice anomalies were primarily confined to the southern Barents Sea. The associated feedback processes and atmospheric circulation anomalies are too weak to excite and sustain a northwestern European anticyclone, thereby limiting the occurrence of such synchronous heatwaves in summer. These findings highlight the growing influence of Arctic Sea ice loss on midlatitude summer extremes and offer new insights into the mechanisms behind Europe‐East Asian synchronous heatwaves in a warming climate.