Along the cold western edge of Antarctica, a glacier that scientists have nicknamed Doomsday is being understood in a new and more sobering light. A recent study in Nature Communications, produced by researchers at UC Irvine and NASA's Jet Propulsion Laboratory, now projects that Thwaites Glacier could add 30 millimetres to global sea levels by 2100, double what earlier estimates suggested. The reason lies not only in the air above the ice but in the warm water creeping beneath it, a hidden process that older models failed to capture. For coastal communities, the number is small in the abstrac
'Doomsday Glacier' Thwaites Melting Faster Than Projected, Doubling Sea-Level Rise Estimate
Mark
The headline says the estimate doubled. What actually changed?
Mimi
The model. Earlier ones couldn't keep up with how fast Thwaites was losing ice. This one includes what happens under the glacier, where warm seawater gets deep beneath the ice.
Mark
And that's the grounding zone?
Mimi
Yes. Sometimes kilometres wide. Seawater lifts the ice during tidal cycles and flushes it with warm, pressurised water, which speeds melting and pulls the glacier off its stabilising ridges.
Luke
Worth being clear that 30mm by 2100 is this team's projection from one model. The source doesn't say other groups have confirmed it.
Mark
Still, they say it matches the observed record.
Mimi
That's Rignot's claim, and it's the key one: older models were slower than satellites showed, and this one reconciles them.
Mark
Thirty millimetres sounds tiny.
Mimi
The rule of thumb is that 10mm means about a metre of coastline retreat, so 30mm could mean up to three metres of beaches, dunes or wetlands.
Luke
That's a general scientific rule of thumb, not a site-specific forecast. Real erosion will vary by coast, and the source gives no local figures.
Mark
So what's unknown?
Luke
Whether other ice-sheet models land in the same place, and how the grounding zone physics plays out over decades. The study doesn't settle that.
El Pulso
- A glacier nicknamed Doomsday now looks set to push sea levels up by 30 millimetres by 2100, twice the earlier forecast.
- Warm seawater is slipping deep beneath the ice in the grounding zone, prying the glacier loose from the ridges that once held it in place.
- Older models could not reconcile slow projected ice movement with satellites recording rapid acceleration, and that gap is now closing.
- Each 10 millimetres of sea-level rise can push coastlines back roughly a metre, so beaches, dunes and wetlands face up to three metres of erosion.
- Scientists are now watching whether other ice-sheet models adopt the same physics and reach similarly alarming, higher projections.
Along the cold western edge of Antarctica, a glacier that scientists have nicknamed Doomsday is being understood in a new and more sobering light. A recent study in Nature Communications, produced by researchers at UC Irvine and NASA's Jet Propulsion Laboratory, now projects that Thwaites Glacier could add 30 millimetres to global sea levels by 2100, double what earlier estimates suggested. The reason lies not only in the air above the ice but in the warm water creeping beneath it, a hidden process that older models failed to capture. For coastal communities, the number is small in the abstract yet large in its consequences, and it invites a quiet recalibration of how much shoreline the coming century may take.
A paper published this month in Nature Communications places a new figure on what Thwaites Glacier, in West Antarctica, could mean for the world's coastlines: 30 millimetres of sea-level rise by 2100. That is double the previous estimate, and the researchers warn it signals more coastal flooding in the decades ahead than anyone had planned for.
The study comes from a team at the University of California, Irvine and NASA's Jet Propulsion Laboratory, who built a model they say captures the glacier's melt more accurately than earlier tools. For years, researchers had struggled with a mismatch: models showed the ice moving slowly, while satellites recorded it speeding up. Eric Rignot, an Earth system scientist at UC Irvine, said the new model includes missing physics and can match the observed loss before projecting much larger future losses.
The key discovery lies beneath the ice. Lead author Mattia Poinelli describes a grounding zone, sometimes kilometres wide, where seawater penetrates deep under the glacier and lifts it with the tides, flushing it with warm, pressurised water. This process loosens Thwaites from the ridges that stabilise it, which speeds its flow and accelerates its decline.
What happens next depends on whether other ice-sheet models adopt the same grounding zone physics. If they do, and reach similar results, the coastlines of the world may be preparing for a larger share of loss than the earlier numbers suggested.
A paper published this month in Nature Communications puts a new number on what the glacier nicknamed "Doomsday" could do to the world's coastlines: 30 millimetres of sea-level rise by 2100. That is twice the previous estimate for Thwaites Glacier in West Antarctica, and the researchers behind it say it points to more coastal flooding risk in the coming decades than had been anticipated.
The work comes from a team at the University of California, Irvine and NASA's Jet Propulsion Laboratory. They built a new computer model that, they say, lets them predict Thwaites melt with greater accuracy than earlier efforts allowed.
The figure matters because of how small increments translate on the shore. The scientific community has previously said that a 10mm rise in sea level can push the coastline back about one metre horizontally. By that rule of thumb, 30mm could erode as much as three metres of beaches, dunes, or wetlands.
Thwaites sits in the Amundsen Sea Embayment sector of West Antarctica, an area that accounts for around one third of the mass loss from the Antarctic Ice Sheet. In recent decades the glacier has retreated and thinned rapidly. Yet scientists have struggled with a mismatch: ice sheet models showed slower movement, while satellite observations showed substantial acceleration of the ice flow.
Eric Rignot, a professor of Earth system science at UC Irvine, said the team's model addresses that gap. Most projections to date, he said, have struggled to match how quickly mass has been lost because of missing physics. The new model, with more complete physics, is able to match the record and then produces projections twice as large as before. He said scientists have documented and quantified the effects of climate change on sensitive ice sheets for decades, but a growing realisation in recent years of what is happening on the undersides of glaciers like Thwaites is leading to an even greater sense of alarm.
Lead author Mattia Poinelli said the work recognises a different arrangement beneath the major ocean-terminating glaciers of the Earth. Satellite observations, he said, show a "grounding zone", sometimes kilometres wide, where warm ocean water reaches deep underneath the ice sheets and causes vigorous melting.
The study's data indicate that seawater penetrates several kilometres beneath grounded ice and lifts it during tidal cycles, flushing the ice with pressurised, warm seawater. Dr Poinelli said the study shows these grounding zone processes are speeding the detachment of Thwaites from the stabilising ridges that hold it. That in turn leads to faster ice flow and further deterioration.
The researchers say the results mean greater risk of, and exposure to, coastal flooding in the decades ahead. What to watch next is whether other ice-sheet models incorporate the same grounding zone physics and arrive at similar, higher projections.
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