Future Sea Surface Temperature as a Key Driver of Antarctic Warming

Abstract Polar amplification—the phenomenon whereby anthropogenic warming is accentuated relative to the global average—has emerged as a central focus of climate research. While Arctic amplification is well‐established, the presence and drivers of Antarctic amplification remain contentious. Using Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations, we demonstrate a robust emergence of Antarctic amplification under the 2°C goal of the Paris Agreement. Sensitivity experiments identify a pivotal role for sea surface temperature (SST) changes in mediating this anthropogenic response. Positive SST anomalies influence Antarctic temperature through dynamic and thermodynamic processes, exerting distinct and contrasting effects. Dynamic processes, characterized by intensification of the Southern Annular Mode (SAM), generally induce continental‐scale cooling. In contrast, thermodynamic processes, specially through enhanced sensible and latent heat fluxes, take precedence over the dynamic effect and drive widespread warming. In a warming climate, these thermodynamic processes are expected to intensify substantially, thereby amplifying the anthropogenic climate signal over Antarctica.