Thwaites Glacier model doubles projected sea-level contribution to 30 mm by 2100
A model calibrated against satellite observations projects that Thwaites Glacier could add up to 30 mm to global sea levels by 2100, twice the average in earlier estimates, even under constant climate forcing. The study, published in Nature Communications, includes a kilometre-wide zone where seawater intrudes beneath grounded ice—physics its authors say helps explain the glacier’s observed retreat and acceleration.
Bottom line — The model puts the chance of Thwaites unpinning from Mouginot Ridge by 2100 at about 60% when the grounding zone is 4–6 km wide.
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Nature Communications’ model estimates 30.1 ± 5.7 mm of sea-level contribution by 2100 for a 5 ± 1 km grounding zone.
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Satellite observations show Thwaites’ fastest-flowing trunk has retreated about 25 km since 1996, according to the study.
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The study’s authors say seawater reaches several kilometres beneath grounded ice, lifting it during tidal cycles and causing melt.
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With a 2–3 km grounding zone, the model puts the chance of unpinning Mouginot Ridge at about 45%; without a zone, or with a 1 km zone, it does not project retreat beyond the ridge by 2100.
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The projections assume climate forcing remains at the 1996–2023 average. The authors note that the model fixes grounding-zone length and excludes changing ice-front position and some ocean feedbacks.