Preprints
https://doi.org/10.5194/egusphere-2024-466
https://doi.org/10.5194/egusphere-2024-466
13 Mar 2024
 | 13 Mar 2024
Status: this preprint is open for discussion.

A fast and unified subglacial hydrological model applied to Thwaites Glacier, Antarctica

Elise Kazmierczak, Thomas Gregov, Violaine Coulon, and Frank Pattyn

Abstract. We present a novel and computationally efficient subglacial hydrological model that represents in a unified way both hard and soft bed rheologies as well as a dynamic switch between efficient and inefficient subglacial discharge. The subglacial model is dynamically linked to a regularized Coulomb friction law, allowing for a coupled evolution of the ice sheet on decadal to centennial time scales. The hydrological model is tested on an idealized marine ice sheet and subsequently applied to the drainage basin of Thwaites Glacier, West Antarctica, that is composed of a heterogeneous (hard/soft) bed. We find that subglacial hydrology embedded in the sliding law accelerates the grounding line retreat of Thwaites Glacier under present-day climatic conditions. Highest retreat rates are obtained for hard bed configurations and/or inefficient drainage systems. We show that the sensitivity is particularly driven by large gradients in effective pressure, more so than the value of effective pressure itself in the vicinity of the grounding line. Clearly, a better understanding of the subglacial system is needed with respect to both the spatial and temporal variability in effective pressure and bed rheological conditions.

Elise Kazmierczak, Thomas Gregov, Violaine Coulon, and Frank Pattyn

Status: open (until 17 May 2024)

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Elise Kazmierczak, Thomas Gregov, Violaine Coulon, and Frank Pattyn

Video supplement

Thwaites videos Elise Kazmierczak, Thomas Gregov, Violaine Coulon, and Frank Pattyn https://github.com/tgregov/ThwaitesVideos

Elise Kazmierczak, Thomas Gregov, Violaine Coulon, and Frank Pattyn

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Short summary
We introduce a new fast model for the water flow beneath the ice sheet capable of handling in a unified way various hydrological and bed conditions. Applying this model to Thwaites Glacier, we show that accounting for this water flow in ice-sheet model projections has the potential to greatly increase the contribution to future sea-level rise. We also demonstrate that the sensitivity of the ice sheet in response to external changes depends on both the efficiency of the drainage and the bed type.