Marine ice-cliff instability modeling shows mixed-mode ice-cliff failure and yields calving rate parameterization

• Published in: Nature Communications
• Main Authors: Crawford, Anna J., Benn, Douglas I., Todd, Joe, Åström, Jan A., Bassis, Jeremy N., Zwinger, Thomas
• Other Authors: RCUK | Natural Environment Research Council
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: General Physics and Astronomy; General Biochemistry, Genetics and Molecular Biology; General Chemistry; Antarctic; West Antarctic Ice Sheet; Antarc*; Antarctica; Ice Sheet; Iceberg*
• Online Access: http://dx.doi.org/10.1038/s41467-021-23070-7; http://www.nature.com/articles/s41467-021-23070-7.pdf; http://www.nature.com/articles/s41467-021-23070-7

Abstract Marine ice-cliff instability could accelerate ice loss from Antarctica, and according to some model predictions could potentially contribute >1 m of global mean sea level rise by 2100 at current emission rates. Regions with over-deepening basins >1 km in depth (e.g., the West Antarctic Ice Sheet) are particularly susceptible to this instability, as retreat could expose increasingly tall cliffs that could exceed ice stability thresholds. Here, we use a suite of high-fidelity glacier models to improve understanding of the modes through which ice cliffs can structurally fail and derive a conservative ice-cliff failure retreat rate parameterization for ice-sheet models. Our results highlight the respective roles of viscous deformation, shear-band formation, and brittle-tensile failure within marine ice-cliff instability. Calving rates increase non-linearly with cliff height, but runaway ice-cliff retreat can be inhibited by viscous flow and back force from iceberg mélange.