| Abstrakt: |
Surface freshening of the Southern Ocean driven by meltwater discharge from the Antarctic ice sheet has been shown to influence global climate dynamics. However, most climate models fail to account for spatially and temporally varying freshwater inputs from ice sheets, introducing significant uncertainty into climate projections. We present the first historically calibrated projections of Antarctic freshwater fluxes (sub‐shelf melting, calving, and surface meltwater runoff) to 2300 that can be used to force climate models lacking interactive ice sheets. Our findings indicate substantial changes in the magnitude and partitioning of Antarctic freshwater discharge over the coming decades and centuries, particularly under very‐high warming scenarios, driven by the progressive collapse of the West Antarctic ice shelves. We project a shift in the form and location of Antarctic freshwater sources, as liquid sub‐shelf melting increases under the two climate scenarios considered, and surface meltwater runoff could potentially become a dominant contributor under extreme atmospheric warming. Plain Language Summary: Melting Antarctic ice releases freshwater into the Southern Ocean, which can have profound impacts on the regional and global climate. In a warming world, the freshwater input into the ocean is expected to increase. However, climate models often poorly represent ice‐sheet mass loss, leading to uncertainty in climate predictions. This study provides new projections of Antarctic freshwater discharge, including contributions from melting at the base of the floating ice shelves, iceberg calving and surface meltwater runoff, up to the year 2300. These projections can be integrated into climate models that lack interactive ice sheets. The results indicate substantial changes in the amount and nature of freshwater discharge from Antarctica in the coming decades and centuries, especially under extreme warming scenarios. We show that liquid melting beneath the floating ice shelves will increase under the two climate scenarios considered, and that surface meltwater runoff could become a major source of freshwater under very high atmospheric warming conditions. Key Points: Up to a four‐fold increase in the magnitude of Antarctic freshwater discharge is projected by 2300 for an extreme climate scenarioWe project a shift in the form and depth of Antarctic freshwater export, as sub‐shelf (and potentially surface) melt outpaces solid calvingOur key findings align with satellite‐based observations and are robust despite uncertainties in climate and ice‐dynamical response [ABSTRACT FROM AUTHOR] |
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