Thwaites 'Doomsday Glacier' Could Contribute Twice the Sea-Level Rise Previously Forecast

A study published in Nature Communications on October 12–13, 2026, by researchers at the University of California, Irvine and NASA's Jet Propulsion Laboratory presents a significantly more alarming picture of Thwaites Glacier's contribution to future sea-level rise. Previous models treated the glacier's grounding line — the boundary where the ice lifts off the underlying bedrock and begins to float — as a fixed point. The new model instead treats it as a kilometres-wide grounding zone subject to tidal pumping: ocean tides repeatedly lift and lower the ice edge, each cycle flushing warm seawater several kilometres further beneath the glacier than earlier assumptions allowed. This sustained contact between warm Atlantic-origin water and the glacier's underside dramatically accelerates basal melting. The model matched historical satellite observations dating back to the 1990s four times more accurately than standard models, lending credibility to its projections. Under the updated scenarios, Thwaites could contribute approximately 30 millimetres — about 1.2 inches — of global sea-level rise by 2100, with a 60 percent probability that the glacier will detach from the stabilising Mouginot Ridge by century's end. Co-author Eric Rignot noted that previous models had long struggled to replicate the observed rate of ice loss, attributing the gap to missing physics now captured by the tidal-pumping mechanism.