Antarctic Meltwater Accelerates Southern Ocean Evolution Under Projected Atmospheric Warming

Abstract Increasing basal meltwater from Antarctic ice shelves may impact the Southern Ocean properties that feed back on the rate of melting. We investigate this feedback in a high‐emissions scenario using an Earth‐system model with interactive ice‐shelf basal melting, an improvement on previous studies that did not have the capability to evolve melt rates and the ocean state self‐consistently. We find that when interactive melt increases, it primarily accelerates the evolution of a spatial pattern of continental shelf warming and cooling that is initiated by freshening and sea‐ice formation decline due to projected atmospheric warming. The competition between enhanced warming at depth from reduced ventilation and enhanced continental shelf cooling from reduced dense water export leads to net 35% reduction in ice‐shelf meltwater input into the Southern Ocean over the 21st century. Omitting this feedback introduces a bias in the timing of projected ocean‐melt‐driven ice loss from Antarctica.