Marine Ice Cliff Instability Mitigated by Slow Removal of Ice Shelves
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unformatted_Clerc_et_al_2019_GRL_merged.pdf
Description
Submitted version
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1.23 MB
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Author(s)
Clerc, Fiona
Minchew, Brent M
Behn, Mark D
Date Issued
2019
Journal
Geophysical Research Letters
Publisher
American Geophysical Union (AGU)
Version
Original manuscript
Abstract
©2019. American Geophysical Union. All Rights Reserved. The accelerated calving of ice shelves buttressing the Antarctic Ice Sheet may form unstable ice cliffs. The marine ice cliff instability hypothesis posits that cliffs taller than a critical height (~90 m) will undergo structural collapse, initiating runaway retreat in ice-sheet models. This critical height is based on inferences from preexisting, static ice cliffs. Here we show how the critical height increases with the timescale of ice-shelf collapse. We model failure mechanisms within an ice cliff deforming after removal of ice-shelf buttressing stresses. If removal occurs rapidly, the cliff deforms primarily elastically and fails through tensile-brittle fracture, even at relatively small cliff heights. As the ice-shelf removal timescale increases, viscous relaxation dominates, and the critical height increases to ~540 m for timescales greater than days. A 90-m critical height implies ice-shelf removal in under an hour. Incorporation of ice-shelf collapse timescales in prognostic ice-sheet models will mitigate the marine ice cliff instability, implying less ice mass loss.
MIT Department
Joint Program in Applied Ocean Physics and Engineering
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1029/2019GL084183
