Ice shelves regulate the ice‐ocean boundary by buttressing the flux of grounded ice into the ocean and are vulnerable to basal melt, which can lead to ice‐shelf thinning and loss of buttressing. Localized, enhanced basal melt can form basal channels, which may impact ice‐shelf stability. Here we investigate the evolution of the Getz Ice Shelf Basal Channel (GISBC) in West Antarctica using a novel suite of geophysical data, including Reference Elevation Model of Antarctica (REMA) digital elevation models, ICESat‐1 and ‐2 altimetry, Operation IceBridge altimetry and radar, and InSAR‐derived ice flow velocities. We describe basal‐channel and ice‐shelf change in both Eulerian and Lagrangian frameworks and document changes in the channel's shape and its lateral motion and estimate basal melting. We find a high degree of spatial and temporal variability in GISBC evolution, with several locations of active basal incision. Incision occurs at rates of up to 22 m a−1at the head of the channel, which is extending toward the grounding line at a rate of ~1 km a−1. Freeboard heights over areas of rapid basal incision are out of hydrostatic equilibrium. The GISBC is also migrating to the northwest, perpendicular to the northeasterly ice flow direction, at an average rate of 70–80 m a−1. The spatiotemporal variability of evolution of the GISBC motivates further characterization of basal channels and their impact on ice‐shelf stability, so that these effects may more readily be incorporated in ice‐ocean models predicting ice flow and sea‐level rise.
Using three independent ice‐flow models and several satellite‐based datasets, we assess the importance of correctly capturing ice‐shelf breakup, shelf thinning, and reduction in basal traction from ungrounding in reproducing observed speed‐up and thinning of Thwaites Glacier between 1995 and 2015. We run several transient numerical simulations applying these three perturbations individually. Our results show that ocean‐induced ice‐shelf thinning generates most of the observed grounding line retreat, inland speed‐up, and mass loss, in agreement with previous work. We improve the agreement with observed inland speed‐up and thinning by prescribing changes in ice‐shelf geometry and a reduction in basal traction over areas that became ungrounded since 1995, suggesting that shelf breakups and thinning‐induced reduction in basal traction play a critical role on Thwaites's dynamics, as pointed out by previous studies. These findings suggest that modeling Thwaites's future requires reliable ocean‐induced melt estimates in models that respond accurately to downstream perturbations.
more » « less- Award ID(s):
- 2152622
- PAR ID:
- 10446458
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 48
- Issue:
- 20
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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