Calving multiplier effect controlled by melt undercut geometry
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Quantifying the impact of submarine melting on calving is central to understanding the response of marine-terminating glaciers to ocean forcing. Modeling and observational studies suggest the potential for submarine melting to amplify calving (the calving multiplier effect), but there is little consensus as to under what conditions this occurs. Here, by viewing a marine-terminating glacier as an elastic beam, we propose an analytical basis for understanding the presence or absence of the calving multiplier effect. We show that as a terminus becomes undercut it becomes more susceptible to both serac failure (calving only of ice that is undercut, driven by vertical imbalance) and rotational failure (full thickness calving of ice behind the grounding line, driven by rotational imbalance). By deriving analytical stress thresholds for these two forms of calving, we suggest that the dominant of the two calving styles is determined principally by the shape of melt undercutting. Uniform undercutting extending from the bed to the waterline promotes serac failure and no multiplier effect, while glaciers experiencing linear undercutting that is greatest at the bed and zero at the waterline are more likely to experience rotational failure and a multiplier effect. Our study offers a quantitative framework for understanding where and when the calving multiplier effect occurs, and, therefore, a route to parameterising the effect in ice sheet-scale models.
Slater , D A , Benn , D I , Cowton , T R , Bassis , J N & Todd , J A 2021 , ' Calving multiplier effect controlled by melt undercut geometry ' , Journal of Geophysical Research - Earth Surface , vol. 126 , no. 7 , e2021JF006191 . https://doi.org/10.1029/2021JF006191
Journal of Geophysical Research - Earth Surface
Copyright © 2021. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
DescriptionThis work was funded by NERC Award NE/P011365/1 (CALISMO: Calving laws for ice sheet models) to PI Benn and NERC IRF NE/T011920/1 (Next generation projections of sea level contribution and freshwater export from the Greenland Ice Sheet) to PI Slater. This work received support from the DOMINOS project, a component of the International Thwaites Glacier Collaboration (ITGC). Support from National Science Foundation (NSF: Grant 1738896) and Natural Environment Research Council (NERC: Grant NE/S006605/1). Logistics provided by NSF-U.S. Antarctic Program and NERC British Antarctic Survey. ITGC Contribution No. ITGC-048.
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