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Abstract:
As the climate warms, the grounded ice sheet and floating ice shelves surrounding Antarctica are losing mass at an increasing rate and injecting the resulting meltwater into the Southern Ocean. However almost all existing coupled climate models lack the ice physics required to represent the dominant sources of Antarctic melt. Previous studies have inserted additional Antarctic meltwater into models, demonstrating a wide array of impacts on the climate system. However, these previous studies have used both different forcing and different models, and have reached differing conclusions on the influence of meltwater-climate feedbacks. The Southern Ocean Freshwater release model experiments InitiAtive (SOFIA) defines a consistent series of experiments, including idealized meltwater experiments, historical experiments, and future scenarios, all with plausible meltwater inputs. Here we present the SOFIA experimental design, and quantify the response and uncertainty to idealized 0.1 Sv release of Antarctic meltwater across a diverse seven member multi-model ensemble. Meltwater increases Southern Ocean stratification, reducing deep convection and vertical heat exchange, which in turn cools the ocean surface, warms the ocean below the thermocline. The surface cooling is associated with a marked increase in Antarctic sea-ice and a global surface cooling and reduction in precipitation. Our results show that while many aspects of the response are coherent amongst models, the magnitude is very model dependent, and heavily influenced by the climatological base state of the Southern Ocean. Moving forward, the SOFIA initiative will work to quantify the climate response to Antarctic meltwater input in plausible historical and future scenarios.
