Critical role of biomass burning aerosols in enhanced historical Indian Ocean warming

The tropical Indian Ocean (TIO) has experienced enhanced surface warming relative to the tropical mean during the past century, but the underlying mechanisms remain unclear. This study uses single-forcing, large-ensemble coupled model simulations to demonstrate that changes in biomass burning (BMB) aerosols have played a critical role in this TIO relative warming. While BMB aerosol changes have little effect on global mean temperatures due to regional cancellation, they significantly influence the warming pattern over tropical oceans. Reduced BMB aerosols over the Indian subcontinent induce TIO warming, while increased BMB aerosols over South America and Africa cause cooling of the tropical Pacific and Atlantic, respectively. This resulting TIO relative warming leads to significant global climate changes, including a westward expanded Indo-Pacific warm pool, fresher TIO waters due to increased rainfall, and an intensified North Atlantic jet stream affecting European hydroclimate.

Yiqun Tian, Shineng Hu, Clara Deser