Antarctica’s “Doomsday” Glacier: Its Collapse Could Trigger Global Floods and Swallow Islands

Glaciers like Antarctica’s Byrd Glacier are showing cracks and movement. Credit: United States Geological Survey

The massive Thwaites glacier in West Antarctica contains enough ice to raise global sea levels by 65cm if it were to completely collapse. And, worryingly, recent research suggests that its long-term stability is doubtful as the glacier hemorrhages more and more ice.

Adding 65cm to global sea levels would be coastline-changing amounts. For context, there’s been around 20cm of sea-level rise since 1900, an amount that is already forcing coastal communities out of their homes and exacerbating environmental problems such as flooding, saltwater contamination and habitat loss.

But the worry is that Thwaites, sometimes called the “doomsday glacier” because of its keystone role in the region, might not be the only glacier to go. Were it to empty into the ocean, it could trigger a regional chain reaction and drag other nearby glaciers in with it, which would mean several meters of sea-level rise. That’s because the glaciers in West Antarctica are thought to be vulnerable to a mechanism called Marine Ice Cliff Instability or MICI, where retreating ice exposes increasingly tall, unstable ice cliffs that collapse into the ocean.

A sea level rise of several meters would inundate many of the world’s major cities – including Shanghai, New York, Miami, Tokyo, and Mumbai. It would also cover huge swathes of land in coastal regions and largely swallow up low-lying island nations like Kiribati, Tuvalu, and the Maldives.

As big as Britain

Thwaites is a frozen river of ice approximately the size of Great Britain. It already contributes around 4% of the global sea-level rise. Since 2000, the glacier has had a net loss of more than 1000 billion tons of ice and this has increased steadily over the last three decades. The speed of its flow has doubled in 30 years, meaning twice as much ice is being spewed into the ocean as in the 1990s.

Map of the Amundsen Sea Basin including the Thwaites glacier. Credit: European Geosciences Union

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Thwaites glacier, the widest in the world at 80 miles wide, is held back by a floating platform of ice called an ice shelf, which restrains the glacier and makes it flow less quickly. But scientists have just confirmed that this ice shelf is becoming rapidly destabilized. The eastern ice shelf now has cracks criss-crossing its surface, and could collapse within ten years, according to Erin Pettit, a glaciologist at Oregon State University.

This work supports research published in 2020 which also noted the development of cracks and crevasses on the Thwaites ice shelf. These indicate that it is being structurally weakened. This damage can have a reinforcing feedback effect because cracking and fracturing can promote further weakening, priming the ice shelf for disintegration.

If Thwaites’ ice shelf did collapse, it would spell the beginning of the end for the glacier. Without its ice shelf, Thwaites glacier would discharge all its ice into the ocean over the following decades to centuries.


New research on Thwaites glacier and its future.

Other unstable glaciers

The ice shelf – which can be thought of as the floating extension of Thwaites glacier – is one of several that scientists are watching closely in the Amundsen Sea Basin, West Antarctica. Several ice shelves that hold back glaciers there, including Thwaites and its next-door neighbour, the Pine Island glacier, are being eroded by rising ocean temperatures.

Warmer ocean water is able to undercut these floating ice shelves, driving melting from below that can thin the ice and weaken it, allowing the cracks and fractures that have been observed at the surface to develop. This ocean-driven melting at the bottom of the ice shelf also pushes the anchoring point where the ice meets the seabed backwards. Because the seabed slopes downwards in the Amundsen Sea, that could eventually trigger a shift as the glaciers lose their footing and retreat rapidly.

Ultimately, if the ice shelves retreat, it means there is less holding the West Antarctic glaciers back – allowing them to accelerate and add more to global sea levels.

However, scientists are still getting to grips with MICI and questions remain about the future of West Antarctic glaciers. While the collapse of Thwaites certainly could trigger a wholesale collapse event, not everyone believes this will happen.

Other work suggests that the destabilization of the Thwaites ice shelf and glacier may not lead to the kind of catastrophic outcomes that some fear. Sea ice and chunks of ice that break away from the collapsing ice shelf and glacier might have a similar restraining effect to the intact ice shelf, nipping the chain reaction in the bud and preventing the sustained collapse of the entire West Antarctic ice sheet.

But while uncertainty remains about exactly what will happen in West Antarctica, one thing is for sure – the retreating Thwaites glacier will continue to add to global sea levels for many years to come.

Written by Ella Gilbert, Postdoctoral Research Associate in Climate Science, University of Reading.

This article was first published in The Conversation.

AntarcticaClimate ChangeGlacierGlobal WarmingThe ConversationUniversity of Reading
Comments ( 11 )
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  • Jmj

    You mean the waterfront property of queen Nancy & the Obummer’s would be underwater? What a sham(e)!

    • TCB

      Childish troll

  • Clyde Spencer

    “For context, there’s been around 20cm of sea-level rise since 1900, an amount that is already forcing coastal communities out of their homes and exacerbating environmental problems such as flooding, saltwater contamination and habitat loss.”

    As Plate Tectonics demonstrates, the surface of the Earth is not static. Indeed, estimates of crustal plate motion rates vary from about 10 to 100 mm/yr, whereas sea level rise is estimated to be on the order of 2 to 3 mm/yr. Anyone who builds substantial coastal structures, whose foundations are closer to sea level than the largest probable storm waves, is a fool.

    “… it COULD trigger a regional chain reaction and drag other nearby glaciers in with it, …”

    I would be more inclined to take these concerns seriously if they assigned numeric probabilities, rather than using ambiguous descriptors such as “could.”

    “It already contributes around 4% of the global sea-level rise.”

    To put that into perspective, that amounts to about 0.08 to 0.1 mm/yr. For comparison, a human hair is about 0.02 to 0.05 mm.

    “The eastern ice shelf now has cracks criss-crossing its surface, and could collapse within ten years, …”

    Cracks imply tension, rather than compression. If the floating ice is actually providing more buttressing than the resistance provided by ice-to-rock friction, I would expect the ice to be under compression.

    “Warmer ocean water is able to undercut these floating ice shelves, driving melting from below that can thin the ice and weaken it, …”

    ALL water is warmer than ice! If it weren’t, it wouldn’t be water. This is nothing new.

    This is another story from The Conversation, which has publicly announced that they will remove reader comments that they disapprove of. So much for open debate about science.

  • Katrina Dymond

    Not long after it lets go. We then enter an ice age.

  • Aaron Franklin

    They never mention the accelerating geothermal blowout driven outburst floods that have shattered Antarctica and Greenlands glaciers hundreds of km inland, and depresurized the volcanic fields under the central icedomes.
    Despite Tsunami currently decimating all the Arctic basin coasts from Greenlands explosive Collapse.

    • Clyde Spencer

      Can you provide a little more information about your claim?

  • Aaron Franklin

    Check the Synthetic Aperture Radar images before you blindly publish misleading articles.
    https://photos.app.goo.gl/CXyAHY67uGryuDUF8
    The Eastern ice shelf of Thwaites HAS collapsed.
    NOT eroded by sea, but blown out by Basal outburst floods from the interior.
    https://www.polarview.aq/
    Choose Antarctica low bandwidth server, SAR hires imagery, area of interest Pine island glacier.

  • Mathme

    SALT WATER CAN BE BELOW THE FREEZING TEMP OF FRESH WATER!! Are you really this illiterate?

    • Clyde Spencer

      Can I assume that your illiterate remark was intended for me?

      Yes, strictly speaking, salt water freezes at about 4 deg F lower temp’ than ice melts. That is what is observed in a laboratory setting. However, the in situ behavior is a little more complex. The ice tends to be much colder than 28 deg F, and the bulk water temp’ tends to be warmer than that. So, if you observe water, one can expect the temperature to be AT LEAST 28.4 deg F, but as a practical matter it will probably be warmer than that. IF it is melting the ice, then it is warmer than 32 deg F. If the water is colder than 28 deg, then ice will be nucleating onto the existing ice and expanding.

      I engaged in some generalizing, but I don’t think that it changes the point I was making by much.

  • Puhiawa

    This article is absurd. Given only 258,000 cubic kilometres of Thwaites is above sea level(the rest being float ice or submerged ice) against 1.5,000,000,000 cubic kilometres of sea water, the impact will be as negligible as it has since the warming which recommenced following the Maunder Minimum.1.5-5mm/annum. The Thwaites has been crumbling into the sea for a century and shall likely do so for the next 1,000 years. Currently Antarctica has been on a cooling trend since consistent measurement started in 1959, IGY, with the exception of periodic melts in the peninsula which are suspected to be volcanism.

  • Tim

    Some global warming crock of bs. The glacier is gloating in the ocean already, and the ice being blocked behind it is also floating, thus the displacement is already accounted for in the water. In short, the water level will not rise at all, let alone the 10 feet the people are claiming. Even if all that was on land and melted, we might see 1 or 2 inches, not 10 feet.