Winter surface air temperature (Tas) over the Barents-Kara Seas (BKS) and other Arctic regions has experienced rapid warming since the late 1990s, linked to concurrent cooling over Eurasia. Multidecadal trends are partly attributed to internal variability, but the generation mechanism is unclear. This study uses observational and model analyses to show that sea ice-air two-way interactions amplify multidecadal variability in sea-ice cover, sea surface temperatures (SST), and Tas from the North Atlantic to BKS, and the Atlantic Meridional Overturning Circulation (AMOC), primarily through surface flux variations. Fixing sea ice in flux calculations substantially reduces (by 20–50%) multidecadal variations in Arctic Tas, North Atlantic SST, and AMOC. Sea ice-air interactions are crucial for multidecadal climate variability in both the Arctic and North Atlantic, similar to air-sea interactions in tropical climates.

Jiechun Deng, Aiguo Dai