Contrasting impacts of Greenland and Antarctic meltwater on tropical circulation

Greenland and Antarctic ice sheets are losing mass rapidly, contributing significantly to sea level rise and altering global climate patterns. Freshwater input from these ice sheets influences tropical climate through ocean-atmosphere interactions, but their distinct impacts remain unclear. Here, we use coupled climate model simulations with imposed meltwater fluxes from Greenland, Antarctica, and both combined under global warming scenarios to investigate tropical responses. We find that Greenland meltwater induces a pronounced southward shift of the Intertropical Convergence Zone (ITCZ) and strengthens the Walker circulation, while Antarctic meltwater causes weaker, opposite-signed effects. Combined meltwater forcing partially offsets these responses, with Greenland effects dominating. These asymmetric impacts arise from differential perturbations to ocean heat transport, atmospheric energy transport, and Atlantic–Pacific pressure-wind adjustments, with cloud-radiative changes acting as secondary modulators. Our results suggest that, under symmetric meltwater perturbations, Northern Hemisphere ice sheet melt may disproportionately influence tropical rainfall and circulation patterns, underscoring the need to represent freshwater forcing pathways in climate projections accurately.