The greater role of Southern Ocean warming compared to Arctic warming in shifting future tropical rainfall patterns

The recent rapid decline in Antarctic sea ice highlights the growing influence of rising Southern Ocean surface temperatures on global climate. While Arctic warming has been extensively studied, the importance of Southern Ocean warming is emerging only now. Multi-model simulations indicate that over 1.5°C of Southern Ocean surface warming can counteract the projected northward shift in zonal-mean precipitation over the tropics by the mid-21st century. SST nudging experiments suggest that a 1.0°C warming in the Southern Ocean could impact tropical precipitation as significantly as a 1.5°C warming in the Arctic. Regionally, Southern Ocean warming increases rainfall in northeastern Brazil while heightening drought risks in the Sahel. These effects are more pronounced than those from a weakening Atlantic meridional overturning circulation. Thus, Southern Ocean warming may play a more crucial role than Arctic warming in shaping tropical climate patterns in the coming decades.