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.
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 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.
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.
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 Erin Pettit, a glaciologist at Oregon State University.
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