Antarctica's 'Doomsday Glacier' could add twice as much to sea levels as feared, study finds
Warm water is reaching deeper beneath Thwaites Glacier than thought, raising the odds it breaks free of the undersea ridge that holds it in place.
At a glance
- A study in Nature Communications led by Mattia Poinelli with NASA's Jet Propulsion Laboratory finds warm seawater is melting Thwaites from below faster than modelled.
- Thwaites could add about 30mm to global sea levels by 2100 — double earlier estimates.
- There is a 60% chance the glacier unpins from the Mouginot Ridge by the end of the century.
- Thwaites is roughly the size of Senegal and already accounts for about 4% of global sea-level rise.
West Antarctica's Thwaites Glacier — nicknamed the "Doomsday Glacier" — is losing ice faster than scientists thought, according to a new study published this week in Nature Communications.
Melting from below
The research, led by glaciologist Mattia Poinelli of the University of California in collaboration with NASA's Jet Propulsion Laboratory, used new models that treat the boundary between the ice and the sea as a broad "grounding zone" rather than a fixed line. Tides pump warm ocean water deep beneath the glacier, melting its core from underneath.
That melting is speeding up Thwaites' "unpinning" from the Mouginot Ridge, an underwater bedrock feature that currently helps stabilise it. The team puts the chance that Thwaites unpins by the end of the century at 60%.
What it means for sea levels
The study suggests Thwaites alone could add about 30mm (1.2 inches) to global sea levels by 2100 — double earlier estimates — even without warming beyond current predictions. The glacier already accounts for about 4% of global sea-level rise, losing around 50 billion tonnes of ice a year and more than 1,000 billion tonnes since 2000.
Thwaites covers about 192,000 square kilometres, roughly the size of Senegal, and sits within the West Antarctic ice sheet, which is 14 times bigger. A full collapse would raise seas catastrophically, but researchers do not expect that for many decades or even centuries.
Why it matters everywhere
Sea-level rise threatens low-lying coastal cities from Karachi and Dhaka to Miami and Lagos. A separate British Antarctic Survey study in July found Thwaites will keep losing ice for at least 150 years even under extreme cooling scenarios. Scientists say more research is needed to pin down future losses, but the direction of travel is clear: ocean warming, driven by burning fossil fuels, is eating away at Antarctica from below.
Questions people are asking
Why is Thwaites called the 'Doomsday Glacier'?
Because it helps hold back the much larger West Antarctic ice sheet. Its collapse, which scientists do not expect for many decades or centuries, would raise sea levels dramatically.
How much ice is Thwaites losing?
About 50 billion tonnes a year, and more than 1,000 billion tonnes since 2000.
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