Thwaites glacier in western Antarctica, the widest glacier on Earth, is sometimes referred to as the ‘Doomsday Glacier, as its collapse could trigger a cascade of glacial collapse in the frozen continent. Spanning about 120km and extending to a depth of about 2,600-3,900ft at its grounding line — where the glacier transitions from a land-attached ice mass to a floating ice shelf in the Amundsen Sea, Thwaites makes headlines frequently. The latest is that the rapid melting of one of Antarctica’s biggest glaciers could end with the ice shelf’s complete collapse in just a few years, as researchers warned at a virtual press briefing last week at the annual meeting of the American Geophysical Union (AGU).
The newest research from the southernmost continent suggests that doomsday may be coming for the dwindling glacier even sooner than expected. Warming ocean water is not just melting Thwaites from below but also loosening the glacier’s grip on the submerged seamount below, making it even more unstable. As the glacier weakens, it then becomes more prone to surface fractures that could spread until the entire ice shelf shatters “like a car window” — and that could happen as soon as three years from now, researchers said at AGU, held in New Orleans and online.
Over the last decade, observations of Thwaites showed that the glacier is changing more dramatically than any other ice and ocean system in Antarctica, on account of human-induced climate change and increased warming in Earth’s atmosphere and oceans. Thwaites has already lost an estimated 1,000bn tonnes  of ice since 2000; its annual ice loss has doubled in the past 30 years, and it now loses about 50bn tonnes more ice than it receives in snowfall per year, according to The International Thwaites Glacier Collaboration (ITGC).
If Thwaites were to break up entirely and release all its water into the ocean, sea levels worldwide would rise by more than 2ft, said ITGC lead co-ordinator Ted Scambos, one of the presenters at AGU and a senior research scientist at the Cooperative Institute for Research in Environmental Sciences. “And it could lead to even more sea-level rise, up to 10ft, if it draws the surrounding glaciers with it,” Scambos said in a statement, referring to the weakening effect one ice shelf collapse can have on other nearby glaciers.
Because Thwaites is changing so quickly and could significantly affect global sea-level rise, more than 100 scientists in the US and the UK are collaborating on eight research projects to observe the glacier from top to bottom; results from several of those teams were presented at AGU. These findings, as well as the ongoing work by ITGC and other scientists in Antarctica, will inform policymakers’ strategies for tracking the impacts of glacial melt on sea-level rise over the coming decades, and how that in turn will affect coastal communities around the world, according to the presenters.
Once-solid ice masses on Thwaites that formerly helped to hold the ice shelf together are also breaking down; the glacier’s icy “tongue” — a part of the ice shelf that protrudes seaward — on the western side is now “just a loose cluster of icebergs and no longer influences this eastern, more stable section of the ice shelf,” according to AGU presenter Erin Pettit, an associate professor of geophysics and glaciology at Oregon State University. When the tongue was more solid, it slowed the flow of the eastern ice shelf toward the ocean. But with the loss of that resistance, the flow of the eastern shelf has shifted over the past 10 years. Cracks are rapidly spreading through the ice, and that portion of the shelf will likely shatter “into hundreds of icebergs” within just a few years, Pettit added.