AMOC Weakening Dominates Global Warming Impacts on Precipitation Over Brazil

Global warming is expected to substantially weaken the Atlantic Meridional Overturning Circulation (AMOC). However, climate models disagree greatly on the magnitude of AMOC weakening due to the large uncertainties in climate change projections, especially in the tropics. Here, we show through multi-model analysis of (CMIP6) future climate change projections that AMOC weakening during the next century will strongly influence precipitation and its extremes over Brazil. Such weakening dominates over the direct global warming impacts, causing drying in the Amazon, while completely mitigating them in northeast Brazil. We trace this to a tropical Atlantic warming, consistent with weakened heat transport along the southern branch of the South Equatorial Current. This induces a cross-equatorial sea surface temperature gradient and changes in latent heat flux, shifting the intertropical convergence zone southward. Our findings highlight the need to reduce uncertainties in the AMOC response to global warming and its oceanic mediated influences on Brazilian climate.