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

• Published in: Nature Communications
• Main Authors: Crawford, Anna, Benn, Douglas I, Todd, Joe, Åström, Jan, Bassis, Jeremy, Zwinger, Thomas
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Glaciology; Calving; Ice failure; Antarctic; West Antarctic Ice Sheet; Antarc*; Antarctica; Ice Sheet; Iceberg*
• Online Access: https://risweb.st-andrews.ac.uk/portal/en/researchoutput/marine-icecliff-instability-modeling-shows-mixedmode-icecliff-failure-and-yields-calving-rate-parameterization(aa085ece-5672-4a7d-9d5a-92a9fbd651cf).html; https://doi.org/10.1038/s41467-021-23070-7; https://research-repository.st-andrews.ac.uk/bitstream/10023/23200/1/Crawford_2021_NatComm_Marine_ice_CC.pdf; https://www.nature.com/articles/s41467-021-23070-7#Sec15

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.