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

TitleRate of Mass Loss Across the Instability Threshold for Thwaites Glacier Determines Rate of Mass Loss for Entire Basin
Publication TypeJournal Article
Year of Publication2018
AuthorsWaibel, M. S., Hulbe C. L., Jackson C. S., and Martin D. F.
JournalGeophysical Research Letters
Volume45
Number2
Pages809-816
Date Published02/2018
Abstract / Summary

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.

URLhttp://dx.doi.org/10.1002/2017gl076470
DOI10.1002/2017gl076470
Journal: Geophysical Research Letters
Year of Publication: 2018
Volume: 45
Number: 2
Pages: 809-816
Date Published: 02/2018

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.

DOI: 10.1002/2017gl076470
Citation:
Waibel, MS, CL Hulbe, CS Jackson, and DF Martin.  2018.  "Rate of Mass Loss Across the Instability Threshold for Thwaites Glacier Determines Rate of Mass Loss for Entire Basin."  Geophysical Research Letters 45(2): 809-816.  https://doi.org/10.1002/2017gl076470.