09 Jun 2023
 | 09 Jun 2023
Status: this preprint is currently under review for the journal TC.

Coupled ice/ocean interactions during the future retreat of West Antarctic ice streams

David T. Bett, Alexander T. Bradley, C. Rosie Williams, Paul R. Holland, Robert J. Arthern, and Daniel N. Goldberg

Abstract. 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 stream flow, 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 WAVI ice sheet model to solve for ice velocities and the 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. We find that Thwaites Glacier dominates the future SLR from the Amundsen Sea sector, with a SLR that is approximately quadratic in time. The future evolution of Thwaites Glacier depends on the life-span 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 and some SLR from this sector is now committed.

David T. Bett et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2023-77', Anonymous Referee #1, 13 Jul 2023
  • RC2: 'Comment on tc-2023-77', Anonymous Referee #2, 18 Jul 2023

David T. Bett et al.

David T. Bett et al.


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Short summary
A new specialised ice/ocean coupled model simulates the future ice sheet evolution in the Amundsen Sea sector of Antarctica. The model predicts substantial ocean-driven ice retreat over the 125-year simulations. The future of small ‘pinning points’ (islands of grounded ice) are an important control on this evolution. Ocean melting is crucial in ungrounding these pinning points, providing the mechanism by which future climate change may affect the sea level contribution from this sector.