Thwaites 'Doomsday Glacier' May Raise Sea Levels Twice as Much as Feared

Scientists at the University of California, Irvine and NASA's Jet Propulsion Laboratory have published a study in Nature Communications revising upward the projected sea-level rise from Antarctica's Thwaites Glacier, often called the 'Doomsday Glacier'. The new model predicts the glacier could contribute up to 30 millimetres of sea-level rise by 2100 — double earlier projections — even without any additional climate warming. The key breakthrough is replacing the long-used concept of a narrow 'grounding line', where the ice shelf lifts off the seabed, with a broader 'grounding zone' that can stretch for several kilometres. Satellite observations show that tidal cycles push warm, pressurised seawater far beneath the grounded ice within this zone, causing melting that is four times more pronounced than traditional models captured. Lead researcher Mattia Poinelli described warm ocean water as 'reaching deep underneath the ice sheets and causing vigorous melting'. The study also finds a 60 percent probability that Thwaites will become unpinned from the Mouginot Ridge — an underwater bedrock formation currently stabilising the glacier — by the end of the century. Once detached, the glacier would retreat across a predominantly retrograde seafloor, likely accelerating further. The Florida-sized glacier already accounts for about 4 percent of global sea-level rise annually, and holds enough ice to raise global oceans by more than 60 centimetres if lost entirely.