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