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Title: Rate of Mass Loss Across the Instability Threshold for Thwaites Glacier Determines Rate of Mass Loss for Entire Basin

Rapid change now underway on Thwaites Glacier (TG) raises concern that a threshold for unstoppable grounding line retreat has been or is about to be crossed. We use a high-resolution ice sheet model to examine the mechanics of TG self-sustained retreat by nudging the grounding line just past the point of instability. We find that by modifying surface slope in the region of the grounding line, the rate of the forcing dictates the rate of retreat, even after the external forcing is removed. Grounding line retreats that begin faster proceed more rapidly because the shorter time interval for the grounding line to erode into the grounded ice sheet means relatively thicker ice and larger driving stress upstream of the boundary. Retreat is sensitive to short-duration re-advances associated with reduced external forcing where the bathymetry allows regrounding, even when an instability is invoked.
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [3] ; ORCiD logo [4]
  1. Portland State Univ., Portland, OR (United States)
  2. Univ. of Otago, Dunedin (New Zealand)
  3. Univ. of Texas, Austin, TX (United States)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 45; Journal Issue: 2; Related Information: ©2018. American Geophysical Union. All Rights Reserved.; Journal ID: ISSN 0094-8276
American Geophysical Union
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21)
Country of Publication:
United States
OSTI Identifier: