Robust and irreversible impacts of an AMOC collapse on tropical monsoon systems: a multi-model comparison

A collapse of the Atlantic Meridional Overturning Circulation (AMOC) would have substantial impacts on global precipitation patterns, especially in the vulnerable tropical monsoon regions. We assess these impacts using four state-of-the-art climate models with bistable AMOC. Spatial and seasonal patterns of precipitation change are remarkably consistent across models. We focus on the South American Monsoon (SAM), the West African Monsoon (WAM), the Indian Summer Monsoon (ISM) and the East Asian Summer Monsoon (EASM). Models consistently suggest substantial disruptions for WAM, ISM and EASM with shorter wet and longer dry seasons (-29.07\%,-18.76\% and -3.78\% ensemble mean annual rainfall change, respectively). Models also agree on changes for the SAM, suggesting rainfall increases overall, in contrast to previous studies. These are more pronounced in the southern Amazon (+43.79\%), accompanied by decreasing dry-season length. Consistently across models, our results suggest major rearranging of all tropical monsoon systems in response to an AMOC collapse.