NASA reported on October 20 that a revised computer model suggests Antarctica’s Thwaites Glacier could contribute more to sea-level rise than some earlier estimates. The research, published October 12 in Nature Communications, projects up to about 30 millimetres by 2100 under constant climate conditions, roughly twice the mean of an earlier model comparison. This figure concerns Thwaites alone, not total global sea-level rise.
The study involves researchers at the University of California, Irvine, NASA’s Jet Propulsion Laboratory and Dartmouth College. According to NASA, the central change is how the model represents the transition from ice resting on land to ice floating in the ocean. Instead of a sharp boundary, it includes a zone where seawater reaches kilometres beneath grounded ice, bringing heat that increases melting.
The team compared simulations with satellite observations of glacier retreat, thinning and acceleration from 1996 to 2023. The paper reports that simulations without a grounding zone were four times less likely to reproduce historical trends. Observations from the ICEYE radar satellite constellation helped reveal how tides lift the ice and allow seawater to penetrate underneath, according to UC Irvine.
The results also connect future retreat to the glacier’s grip on underwater ridges. UC Irvine said simulations with a grounding zone four to six kilometres wide indicate about a 60 percent probability of detachment from Mouginot Ridge by 2100. The paper’s higher sea-level estimate is approximately 30 millimetres with an uncertainty of six millimetres. These are conditional model results, rather than a guaranteed outcome or evidence of a sudden collapse.
NASA said the work could improve information available to coastal regions facing rising seas. However, the authors identify limitations, including the assumption that the grounding zone has a fixed length and the omission of some interactions between ocean water and the changing cavity beneath floating ice. Future modelling will need to represent how that zone evolves, while further observations can help test the projections.
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