A new Antarctic ice model projects the so-called Doomsday Glacier could add up to 1.2 inches of sea-level rise by 2100, double earlier estimates, researchers say.
Warm ocean water is cutting farther under western Antarctica’s Thwaites Glacier than older ice sheet models assumed, according to a fresh paper in Nature Communications from University of California scientists.
The Daily Mail reported that the revised physics roughly doubles the glacier’s projected contribution to global sea level by the end of the century and points to higher coastal flood exposure in the decades ahead.
Lead author Dr. Mattia Poinelli of UC Irvine and co-author Professor Eric Rignot built the model around satellite measurements of small surface motions from Finland’s ICEYE constellation. Their reconstruction of change from the 1990s to now comes out about four times more severe than traditional runs.
Thwaites is a vast river of ice in the Amundsen Sea sector. It covers an area larger than Great Britain and sits roughly the size of Washington state, with ice up to 13,100 feet thick in places.
Scientists have long treated the “grounding line” as a thin, mostly stable boundary where the glacier leaves bedrock and starts to float. Poinelli said that picture no longer fits what the instruments show.
Poinelli put the shift this way:
"Glaciologists have long based their assumptions of ice sheet dynamics on the "grounding line", a discrete, narrow and mostly stable demarcation where ice leaves the land and begins floating on water."
He added:
"We have come to acknowledge a different arrangement beneath Earth's major ocean-terminating glaciers."
In the new framing, a broader “grounding zone” matters more. Pressurized warm seawater pushes several miles beneath ice that still rests on the bed. Tides lift the ice, flush that water through, and speed melt at the base.
Rignot said the gap between old forecasts and real loss came from physics the earlier tools left out.
"Most projections to date have struggled to match the rapidity of the mass loss because of missing physics; our new model with more complete physics can match the record and then produces projections that are twice as large as before."
Under the updated run, Thwaites alone could contribute as much as 1.2 inches, or 30 millimeters, of global sea-level rise by 2100. That figure is described as double prior estimates tied to the same glacier.
Rignot tied the result to flood planning on the coasts:
"These results predict greater risk of and exposure to coastal flooding than anticipated in the coming decades."
The model also gives Thwaites a 60 percent chance of losing its hold on the Mouginot Ridge by century’s end. Once that pin is gone, Poinelli said, retreat continues across a seafloor that slopes downward toward the next high point, the South Ridge.
"Once that ridge is unpinned, the glacier will continually retreat across a predominantly retrograde seafloor toward its next topographic high, the South Ridge."
Full collapse numbers in the same reporting run higher and are not identical across every background figure. One figure puts complete loss of Thwaites at about 26 inches of sea-level rise. Separate background estimates speak of one to two meters, or three to six feet, from Thwaites, with potential for more than twice that if the wider West Antarctic Ice Sheet went with it. The interior bed lies more than 1.2 miles below sea level, which is why researchers have long called the region unstable.
The new paper does not invent the glacier’s recent behavior. It tries to catch up with it.
Flow at Thwaites picked up in a serious way in the 1970s. Annual ice discharge from the wider region has climbed 77 percent since 1973. From 1992 to 2011, the center of the grounding line stepped back nearly nine miles. Thinning and retreat have stayed fast over the last few decades.
On the eastern flank, the Thwaites Eastern Ice Shelf still acts as a supporting barrier. That shelf is more than 1,150 feet thick and covers about 580 square miles, roughly the area of Greater London. Dr. Robert Larter, a marine geophysicist with the British Antarctic Survey, said in remarks reported from May that breakup of the shelf was “very likely to happen sometime this year.”
Relative timing in that warning was not pinned to a calendar year in the available account. The modeling paper itself was presented without a clear public date in the same write-up.
The study’s core claim is narrow and technical. Older grounding-line assumptions under-ran the mass loss satellites already measured. Add tidal seawater intrusion under the ice, and the same history looks about four times sharper. Push that framework forward, and the 2100 contribution from Thwaites roughly doubles, to a top end of 1.2 inches, with a better-than-even shot at unpinning from Mouginot Ridge before 2100.
Those are model outputs and researcher warnings, not tide-gauge readings from American boardwalks. No injuries, shutdowns, or measured flood damages are attached to the paper. The authors argue coastal exposure rises if the projection holds. The public still has to separate a 30-millimeter century-scale line item from the much larger total-collapse figures that circulate in the same coverage.
Thwaites will keep moving on the schedule the ice and the ocean set. Taxpayers footing the bill for coastal projects deserve forecasts that match the satellite record, not another round of missing physics dressed up as destiny.
