Impact of glacial isostatic adjustment on zones of potential grounding line persistence in the Ross Sea Embayment (Antarctica) since the Last Glacial Maximum

• Published in: The Cryosphere
• Main Authors: S. T. Kodama, T. Pico, A. A. Robel, J. E. Christian, N. Gomez, C. Vigilia, E. Powell, J. Gagliardi, S. Tulaczyk, T. Blackburn
• Format: Article
• Language: English
• Published: Copernicus Publications 2025-08-01
• Online Access: https://tc.copernicus.org/articles/19/2935/2025/tc-19-2935-2025.pdf
• ISSN: 1994-0416; 1994-0424

<p>Ice streams in the Ross Sea Embayment (West Antarctica) retreated up to 1000 km since the Last Glacial Maximum (LGM). One way that bathymetry influenced this retreat was through the presence of local bathymetric highs, or pinning points, which decreased ice flux through the grounding line and slowed grounding line retreat. During this time, glacial isostatic adjustment vertically shifted the underlying bathymetry, altering the grounding line flux. Continental-scale modeling efforts have demonstrated how solid Earth–ice sheet interactions impact the deglacial retreat of marine ice sheets; however, these models are too coarse to resolve small-scale bathymetric features. We pair a high-resolution bathymetry model with a simple model of grounding line stability in an ensemble approach to predict zones of potential grounding line persistence in the Ross Sea Embayment for given combinations of surface mass balance rate, degree of ice shelf buttressing, basal friction coefficient, and bathymetry (corrected for glacial isostatic adjustment using three different ice sheet histories). We find that isostatic depression within the interior of the Ross Sea Embayment during the LGM restricts zones where grounding lines can persist to near the edge of the continental shelf. Most grounding lines cannot persist near the present-day grounding line until sufficient uplift has occurred (mid-Holocene; <span class="inline-formula">∼</span> 5 ka), and this uplift causes a net upstream migration of grounding line persistence zones across the deglaciation. Additionally, our results show that coarse-resolution bathymetry underpredicts possible stable grounding line positions, particularly near the present-day grounding line, highlighting the importance of bathymetric resolution in capturing the impact of glacial isostatic adjustment on ice stream stability.</p>