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Context

• Antarctica’s “Doomsday Glacier” – nicknamed because its collapse could drive catastrophic sea level rise – is melting rapidly in unexpected ways, according to new research published in the journal Nature.

About

• Thwaites Glacier, nicknamed the Doomsday Glacier, is an unusually broad and vast Antarctic glacier.
• It flows into Pine Island Bay, part of the Amundsen Sea, east of Mount Murphy, on the Walgreen Coast of Marie Byrd Land.
• Thwaites Glacier is closely monitored for its potential to raise sea levels. Along with the Pine Island Glacier, it has been described as part of the "weak underbelly" of the West Antarctic Ice Sheet, because of its apparent vulnerability to significant retreat.

Importance of Doomsday Glacier and Concerns

• 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.
• 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 destabilised. The eastern ice shelf now has cracks criss-crossing its surface, and could collapse within ten years, according to Oregon State University.
• There is a 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.
• Without its ice shelf, Thwaites glacier would discharge all its ice into the ocean over the following decades to centuries.

Implications

• 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 haemorrhages 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.
• Thwaites, is sometimes called the “doomsday glacier” because of its keystone role in the region.
• 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 metres 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 metres 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.

https://edition.cnn.com/2023/02/15/world/thwaites-doomsday-glacier-sea-level-climate-intl

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