Tropical Indian Ocean Warming: A Key Driver of Future Hadley Circulation Changes

The rapid warming of the oceans is increasingly recognized for its significant impacts on the climate system and is a central issue in the Climate Variability and Predictability (CLIVAR) research program. However, the effect of future ocean warming—particularly regional ocean warming—on the Hadley Circulation (HC) remains poorly understood. This study addresses the regional contributions of tropical ocean warming to future HC changes, focusing on the 1.5°C, 2°C, and 3°C warming scenarios outlined in the Paris Agreement. Through large ensemble numerical simulations, we demonstrate for the first time that the tropical Indian Ocean dominates future HC changes, while the tropical Pacific Ocean is the main source of uncertainty in HC projections. These results provide critical insights for improving Earth system models and enhancing the projection of tropical atmospheric circulation. Furthermore, they offer a scientific foundation for monitoring and forecasting climate risks associated with future HC shifts, supporting the development of key policy decisions.

Sun, Y., Ramstein, G., Fedorov, A.V., Ding, L., & Liu, B. (2025). Tropical Indian Ocean drives Hadley circulation change in a warming climate. National Science Review, 12(1), nwae375, https://doi.org/10.1093/nsr/nwae375