Model insights into bed control on retreat of Thwaites Glacier, West Antarctica

Thwaites Glacier (TG) plays an important role in future sea-level rise (SLR) contribution from the West Antarctic Ice Sheet. Recent observations show that TG is losing mass, and its grounding zone is retreating. Previous modeling has produced a wide range of results concerning whether, when, and how...

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Bibliographic Details
Published in:Journal of Glaciology
Main Authors: Emily Schwans, Byron R. Parizek, Richard B. Alley, Sridhar Anandakrishnan, Mathieu M. Morlighem
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press 2023
Subjects:
Glacier modelling
glaciological model experiments
ice dynamics
ice-ocean interaction
Environmental sciences
GE1-350
Meteorology. Climatology
QC851-999
Antarc*
Antarctic
Antarctica
Ice Sheet
Ice Shelf
Journal of Glaciology
Thwaites Glacier
West Antarctica
Online Access:https://doi.org/10.1017/jog.2023.13
https://doaj.org/article/49c795a45d994bd7befe71ea2df13313
Description
Summary:Thwaites Glacier (TG) plays an important role in future sea-level rise (SLR) contribution from the West Antarctic Ice Sheet. Recent observations show that TG is losing mass, and its grounding zone is retreating. Previous modeling has produced a wide range of results concerning whether, when, and how rapidly further retreat will occur under continued warming. These differences arise at least in part from ill-constrained processes, including friction from the bed, and future atmosphere and ocean forcing affecting ice-shelf and grounding-zone buttressing. Here, we apply the Ice Sheet and Sea-level System Model (ISSM) with a range of specifications of basal sliding behavior in response to varying ocean forcing. We find that basin-wide bed character strongly affects TG's response to sub-shelf melt by modulating how changes in driving stress are balanced by the bed as the glacier responds to external forcing. Resulting differences in dynamic thinning patterns alter modeled grounding-line retreat across Thwaites' catchment, affecting both modeled rates and magnitudes of SLR contribution from this critical sector of the ice sheet. Bed character introduces large uncertainties in projections of TG under equal external forcing, pointing to this as a crucial constraint needed in predictive models of West Antarctica.

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