31 / 2026-01-19 11:09:29

ENSO’s Changing Grip on Bering Sea Ice: The Emerging Control of the North Pacific Meridional Mode

ENSO-NPMM coupling; Bering Sea Ice; Pacific atmospheric wave train; mid-1990s

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Bering Sea winter sea ice (BSWI), vital for regional climate, ecosystem, and livelihoods, is significantly influenced by El Niño-Southern Oscillation (ENSO). Here we identify a shift in the ENSO-BSWI relationship. Pre-mid-1990s, traditional eastern Pacific ENSO dominated, driving a positive ENSO-BSWI linkage; Post-mid-1990s, more frequent Central Pacific (CP) ENSO events reversed this relationship to negative. Observations and model experiments show CP El Niño coupled with positive-phase North Pacific Meridional Mode (NPMM) redirects poleward-propagating Rossby wave trains, enhancing Bering Sea southerlies. This suppresses ice advection, intensifies warm air intrusion, and reduces BSWI. Strengthened CP ENSO-NPMM coupling and heightened NPMM variability amplify this teleconnection, increasing its influence on BSWI by 38.9% versus NPMM alone. Our findings underscore the growing role of subtropical and tropical Pacific climate interactions in subarctic sea ice variability and highlight the need for improved climate models that capture ENSO diversity, NPMM dynamics, and subtropical-subarctic teleconnections to enhance BSWI projections under climate change.