(CNN) – Scientists using icebreaking ships and underwater robots have discovered that the Thwaites Glacier in Antarctica is melting at an accelerating rate and could be on an irreversible path to collapse, spelling catastrophe for global sea level rise.
Since 2018, a team of scientists forming the International Thwaites Glacier Collaboration has been studying Thwaites – often dubbed the “glacier at the end of the world” – closely to better understand how and when it might collapse.
Their conclusions, collected in a series of studies, offer the clearest picture to date of this complex and constantly changing glacier. The outlook is “bleak,” say the scientists in a report published this Thursday, in which they reveal the main conclusions of their six years of research.
They have found that the rapid loss of ice will accelerate this century. According to Rob Larter, a marine geophysicist at the British Antarctic Survey and a member of the ITGC team, the Thwaites retreat has accelerated considerably over the past 30 years. “Our findings indicate that the retreat will be greater and faster,” he said.
Scientists predict that Thwaites and the Antarctic ice sheet could collapse within 200 years, with devastating consequences.
Thwaites contains enough water to raise sea levels by more than 60 centimeters. But because it also acts as a cork, holding back the vast Antarctic ice sheet, its collapse could ultimately cause a rise in sea levels of around 3 metres, devastating coastal communities from Miami and London to Bangladesh and the Pacific islands.
Scientists have long known that Florida-sized Thwaites was vulnerable, in part because of its geography. The land it sits on is tilted downward, meaning that as it melts, more ice is exposed to relatively warm ocean water.
Until now, however, relatively little was known about the mechanisms of its withdrawal. “Antarctica remains the greatest threat to understanding and predicting future sea level rise,” ITGC scientists say in a statement.
Over the past six years, scientists have carried out a series of experiments aimed at clarifying the situation.
They sent a torpedo-shaped robot called Icefin to the Thwaites mooring line, the point at which ice rises from the seabed and begins to float, a key point of vulnerability.
Kiya Riverman, a glaciologist at the University of Portland, says the first clip of Icefin swimming to the anchor line was exciting. “I think it had the same emotional impact for glaciologists as landing on the Moon did for the rest of society,” she declared at a conference. “It was a great event. “We were seeing this place for the first time.”
Through images streamed by Icefin, they discovered that the glacier is melting in unexpected ways, with warm ocean water able to funnel through deep cracks and “staircase” formations in the ice.
Another study used satellite and GPS data to analyze the impact of tides and found that sea water could penetrate more than 10 kilometers beneath Thwaites, compressing the warm water under the ice and causing rapid melting.
Other scientists delved into Thwaites’ story. A team including Julia Wellner, a professor at the University of Houston, analyzed marine sediment cores to reconstruct the glacier’s past and found that it began to retreat rapidly in the 1940s, likely triggered by a very strong El Niño event. , a natural fluctuation in climate that often has a warming effect.
These results “teach us roughly the behavior of ice, adding more detail than you get by looking at modern ice alone,” Wellner told CNN.
Amid the gloom, there was also good news about a process that scientists fear could cause a rapid thaw.
There are concerns that if the Thwaites Ice Shelves collapse, they will leave towering ice cliffs exposed to the ocean. These tall cliffs could easily become unstable and fall into the ocean, exposing even higher cliffs behind them, with the process repeating itself over and over again.
However, computer models have shown that, although this phenomenon is real, the chances of it occurring are lower than feared.
That doesn’t mean Thwaites is safe.
Scientists predict that the entirety of Thwaites and the Antarctic ice sheet behind it could disappear by the 23rd century. Even if humans stop burning fossil fuels quickly – which is not happening – it may be too late to save them.
Although this phase of the ITGC project is coming to an end, scientists say that much more research is still needed to understand this glacier complex and to know if its retreat is already irreversible.
“While progress has been made, we remain deeply uncertain about the future,” says Eric Rignot, a glaciologist at the University of California, Irvine and part of the ITGC. “I continue to be very concerned that this sector of Antarctica is already in a state of collapse.”
