Inter-basin contrast in the Southern Ocean warming

The Southern Ocean (SO) is a major contributor to global ocean heat uptake, exhibiting deep-reaching warming trends within the 35°S-55°S band. Here, we reveal a notable inter-basin contrast in the SO warming rates. Over the past six decades, the warming of the 0-700 m Atlantic-Indian sector was 40.0 ± 5.7% faster than the Pacific sector, nearly doubling at ~44°S. Ocean-only and coupled model experiments suggest that this basin-scale contrast arises from alterations in wind-driven heat redistribution rather than surface heating. Specifically, the intensification and poleward migration of westerly winds are more prominent in the Atlantic-Indian sector, leading to stronger upper-layer heat convergence. The inter-basin warming contrast is projected to persist and amplify throughout the remainder of the 21st century. This study highlights the inter-basin contrast in the past and future SO warming, with useful implications for understanding regional changes in the SO climate, ice mass, and marine ecosystems.