It might sound like something from a sci-fi disaster film, but scientists say the threat of the Doomsday Glacier is very real, and potentially catastrophic.
Deep in West Antarctica lies Thwaites Glacier, a colossal and unstable mass of ice that researchers have ominously dubbed the “Doomsday Glacier.” Its nickname isn’t an exaggeration. If Thwaites collapses, the consequences could be felt around the globe.
Roughly the size of Great Britain and more than 2 kilometres thick in parts, Thwaites holds enough water to significantly raise sea levels worldwide. Scientists warn that if it were to fully give way, global sea levels could rise by around 65 centimetres, per the British Antarctic Survey.
“If Thwaites Glacier collapses it would cause a rise of around 65cm (25 inches) in sea level,” said Dr Alastair Graham of the University of South Florida.
That might not seem like a dramatic number on its own, but the real-world impact would be devastating. A rise of just half a metre would mean regular flooding for many coastal cities. Places like New York, London, and Bangkok could face chronic inundation. Even Australia isn’t spared: large swathes of its population live in low-lying suburbs in Sydney, Melbourne, and the Gold Coast, making them especially vulnerable to even modest sea level rise.
And the crisis isn’t some distant future scenario. Thwaites is already melting, fast. Its flow of ice into the sea has doubled since the 1990s, and the floating ice shelf that helps hold it back is cracking under mounting stress.
“This year is really different,” said Ted Scambos, a glaciologist at the University of Colorado Boulder and leader of the Science Coordination Office for the International Thwaites Glacier Collaboration, speaking to CNN.
“It’s very difficult to recover from this in one season. The game has changed.”
Some researchers fear parts of that ice shelf could disintegrate in the coming years. If that happens, the glacier’s movement into the ocean could accelerate dramatically, and with it, the contribution to rising seas.
Even more worrying is the role Thwaites plays in the larger Antarctic ice system. Often described as a “keystone” glacier, its collapse could destabilise surrounding glaciers, setting off a chain reaction that could eventually unlock enough land-based ice to raise sea levels by several metres over the coming centuries.
While that kind of worst-case scenario would unfold over a longer timeline, scientists stress that Thwaites is already contributing to sea level rise, and how quickly it worsens depends heavily on our emissions and the warming they cause.
This isn’t just about Thwaites either. Antarctica as a whole is sending out warning signals. According to the National Snow and Ice Data Center, “Antarctic sea ice has hit record-low levels for winter.”
While melting sea ice doesn’t directly raise sea levels, it plays a vital role in Earth’s climate system. It reflects sunlight like a mirror, helping to keep the planet cool. As that ice disappears, darker ocean waters absorb more heat, further warming the region.
That warmth can then seep beneath floating ice shelves (like the one at Thwaites) and cause them to melt from below. When those shelves weaken, they can no longer act as barriers, and inland glaciers begin sliding more quickly into the sea.
This chain reaction is exactly what scientists fear could happen across West Antarctica. The frozen parts of our world are shifting faster than expected, and those changes may reshape coastlines, displace millions, and ignite enormous economic and humanitarian crises in the decades to come.
The message from scientists is clear: the time to act on climate change is now.