Coupled ice–ocean interactions during future retreat of West Antarctic ice streams in the Amundsen Sea sector

The Amundsen Sea sector has some of the fastest-thinning ice shelves in Antarctica, caused by high, ocean-driven basal melt rates, which can lead to increased ice streamflow, causing increased sea level rise (SLR) contributions. In this study, we present the results of a new synchronously coupled ic...

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Bibliographic Details
Published in:The Cryosphere
Main Authors: D. T. Bett, A. T. Bradley, C. R. Williams, P. R. Holland, R. J. Arthern, D. N. Goldberg
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2024
Subjects:
Environmental sciences
GE1-350
Geology
QE1-996.5
Amundsen Sea
Antarc*
Antarctic
Antarctica
Ice Sheet
Ice Shelf
Ice Shelves
The Cryosphere
Thwaites Glacier
Thwaites Ice Shelf
Online Access:https://doi.org/10.5194/tc-18-2653-2024
https://doaj.org/article/db97872ee69d478a851896721d51a542
Description
Summary:The Amundsen Sea sector has some of the fastest-thinning ice shelves in Antarctica, caused by high, ocean-driven basal melt rates, which can lead to increased ice streamflow, causing increased sea level rise (SLR) contributions. In this study, we present the results of a new synchronously coupled ice-sheet–ocean model of the Amundsen Sea sector. We use the Wavelet-based, Adaptive-grid, Vertically Integrated ice sheet model (WAVI) to solve for ice velocities and the Massachusetts Institute of Technology general circulation model (MITgcm) to solve for ice thickness and three-dimensional ocean properties, allowing for full mass conservation in the coupled ice–ocean system. The coupled model is initialised in the present day and run forward under idealised warm and cold ocean conditions with a fixed ice front. We find that Thwaites Glacier dominates the future SLR from the Amundsen Sea sector, with a SLR that evolves approximately quadratically over time. The future evolution of Thwaites Glacier depends on the lifespan of small pinning points that form during the retreat. The rate of melting around these pinning points provides the link between future ocean conditions and the SLR from this sector and will be difficult to capture without a coupled ice–ocean model. Grounding-line retreat leads to a progressively larger Thwaites Ice Shelf cavity, leading to a positive trend in total melting, resulting from the increased ice basal surface area. Despite these important sensitivities, Thwaites Glacier retreats even in a scenario with zero ocean-driven melting. This demonstrates that a tipping point may have been passed in these simulations and some SLR from this sector is now committed.

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