Western North Pacific influences on the interannual to decadal variability of Barents-Kara Sea ice during spring.

Spring sea ice cover in the Barents-Kara Seas (BKS) exhibits notable interannual to decadal variability with spatial patterns distinct from winter. While previous studies suggest that internal climate variability dominates, the specific drivers remain to be identified. Using observations and model simulations, we reveal that atmospheric teleconnection from the western North Pacific accounts for ~26 to 40% of the interannual to decadal variability of the BKS sea ice during February-March-April. A poleward-propagating Rossby wave train, forced by divergent winds associated with the Western Pacific (WP) pattern, links WP to BKS sea ice variability by inducing lower-atmospheric circulation anomalies over the North Atlantic that enhance poleward heat and moisture transport. Furthermore, decadal shifts in the WP pattern, potentially originating from the Pacific Decadal Oscillation, have modulated the sea ice trend over the BKS, driving accelerated retreat in the 2000s and a slowdown after 2015. A projected transition of WP to its negative phase may accelerate BKS sea ice loss in the coming decade.