The linkage between autumn Barents-Kara sea ice and European cold winter extremes

While the Arctic's accelerated warming and sea ice decline have been associated with Eurasian cooling, debates persist between those attributing this to sea ice retreat and those to internal variability. Using the observational data to track month-to-month variabilities, we show that the variability of sea ice over the Barents-Kara Seas in autumn is related to extreme cold winters over much of the European continent. The winter temperature change in Europe is a direct response to a stationary Rossby wave generated by the lower troposphere diabatic heat anomaly as a result of sea ice loss over the Barents-Kara Seas in autumn, leading to a negative phase of North Atlantic Oscillation and more frequent episodes of the atmospheric blocking over Greenland and the North Atlantic. The negative phase of the North Atlantic Oscillation and enhanced blocking are closely related and mutually reinforcing, shaping the spatial distribution of cold anomalies over much of the European continent. Our results suggest a link between the unusual decrease in Barents-Kara Sea ice during autumn and the occurrence of intense European weather extremes in subsequent winter months. Delving deeper into this relationship on monthly time scales can enhance our predictive capabilities for midlatitude extreme events.