The floating ice shelves along the seaboard of the Antarctic ice sheet restrain the outflow of upstream grounded ice1,2. Removal of these ice shelves, as shown by past ice-shelf recession and break-up, accelerates the outflow3,4, which adds to sea-level rise. A key question in predicting future outflow is to quantify the extent of calving that might precondition other dynamic consequences and lead to loss of ice-shelf restraint. Here we delineate frontal areas that we label as ‘passive shelf ice’ and that can be removed without major dynamic implications, with contrasting results across the continent. The ice shelves in the Amundsen and Bellingshausen seas have limited or almost no ‘passive’ portion, which implies that further retreat of current ice-shelf fronts will yield important dynamic consequences. This region is particularly vulnerable as ice shelves have been thinning at high rates for two decades5 and as upstream grounded ice rests on a backward sloping bed, a precondition to marine ice-sheet instability6,7. In contrast to these ice shelves, Larsen C Ice Shelf, in the Weddell Sea, exhibits a large ‘passive’ frontal area, suggesting that the imminent calving of a vast tabular iceberg8 will be unlikely to instantly produce much dynamic change.
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This study received primary funding from the French National Research Agency (ANR) under the SUMER (Blanc SIMI 6) 2012 project referenced as ANR-12-BS06-0018. Results presented in this publication are based on numerical simulations conducted either at CIMENT (Calcul Intensif Modélisation Expérimentation Numérique et Technologique), the high-performance computing centre of the Grenoble University, which is supported on local, county and regional levels via the CIRA project (Calcul intensif en Rhône Alpes), or at the CINES (Centre Informatique National de l’Enseignement Supérieur) computing centre under allocation 2015-016066 from GENCI (Grand Equipement National de Calcul Intensif). Results presented here also received support and benefited from the Elmer/Ice development team at the CSC-IT Center for Science Ltd (Finland). The velocity analysis on Wilkins was funded by the German Research Foundation (DFG) within the priority programme 1158 Antarctic Research under contract number BR2105/8-1 and as co-fund action to the HGF Alliance Remote Sensing and Earth System Dynamics. During the revision phase of the manuscript, the first author received funding from the DFG-project FU1032/1-1.
The authors declare no competing financial interests.
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Fürst, J., Durand, G., Gillet-Chaulet, F. et al. The safety band of Antarctic ice shelves. Nature Clim Change 6, 479–482 (2016). https://doi.org/10.1038/nclimate2912
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