La Niña’s longevity shapes Bering Sea ice fate

La Niña events vary widely in duration, from single-year to multi-year. However, their influence on Bering Sea ice concentration remains unclear. Here, we show that single-year and multi-year La Niña events produce contrasting impacts on spring Bering Sea ice concentration. Multi-year events mitigate the long-term decline—without them, the rate of ice loss would be 11.1% higher. During the first two decay-phase springs, multi-year events generate a negative meridional Rossby wave train that induces northerly wind anomalies, enhancing cold advection and upward sensible heat fluxes, thereby slowing ice loss. In contrast, single-year events coincide with a positive North Pacific Oscillation pattern that drives southerly anomalies, reduces heat fluxes, and suppresses ice formation. These results identify La Niña duration as a key predictor of Bering Sea ice variability. An increasing frequency of multi-year events could therefore help buffer spring Bering Sea ice decline under global warming, highlighting the importance of tropical–subarctic teleconnections in subarctic climate variability.