CNN
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Scientists using icebreaking ships and underwater robots have discovered that Antarctica’s Thwaites Glacier is melting at an accelerating rate and may be on an irreversible path toward collapse, threatening catastrophic global sea level rise.
Since 2018, a team of scientists forming the International Thwaites Glacier Collaboration has been studying Thwaites Glacier — often called the “Doomsday Glacier” — up close to understand how and when it might collapse.
Their findings, presented across a range of studies, offer the clearest picture yet of this complex and ever-changing glacier. The outlook is “bleak,” the scientists said in a report published Thursday, revealing the key findings of six years of research.
The researchers found that rapid ice loss is set to accelerate this century. Rob Larter, a marine geophysicist at the British Antarctic Survey and a member of the Antarctic Ocean Institute team, said the retreat of Thwaites has accelerated dramatically over the past 30 years. “Our results suggest that it is set to retreat even more rapidly and more rapidly,” he said.
Scientists predict that Thwaites and the Antarctic ice sheet will collapse within 200 years, which could have devastating consequences.
The Thwaites River holds enough water to raise sea levels by more than two feet. But because it also acts like a cork, holding in Antarctica’s vast ice sheet, its collapse could eventually cause sea levels to rise by about 10 feet, devastating coastal communities from Miami and London to Bangladesh and the Pacific Islands.
Scientists have long known that the Florida-sized Thwaites River is at risk, in part because of its geography. The land it sits on slopes downward, meaning that as it melts, more of its ice is exposed to relatively warm ocean water.
But previously, relatively little was known about the mechanisms behind its retreat. “Antarctica remains the biggest wild card for understanding and predicting future sea level rise,” scientists at the International Climate Institute said in a statement.
Over the past six years, a host of experiments by scientists have sought to bring more clarity.
They sent a torpedo-shaped robot called Icefin to the Thwaites stranding line, the point where ice rises from the sea floor and begins to float, a major weak point.
The first video of Ice Wedge swimming toward the contact line with Earth was very emotional, said Kia Riverman, a glaciologist at Portland State University. “For glaciologists, I think it had the same emotional impact that the moon landing probably had on the rest of society,” she told a new conference. “It was a huge event. We were seeing this place for the first time.”
Through images sent back by the Icefin probe, scientists discovered that the ice is melting in unexpected ways, as warm ocean water is able to flow through deep cracks and “ladder” formations in the ice.
Another study used satellite and GPS data to study the effects of tides, and found that seawater was able to push more than six miles under the Thwaites River, compressing warm water under the ice and causing rapid melting.
More scientists have delved into Thwaites’ history. A team including Julia Willner, a professor at the University of Houston, analyzed marine sediment samples to reconstruct the glacier’s past, and found that it began retreating rapidly in the 1940s, likely due to a very strong El Niño—a natural climate fluctuation that tends to produce a warming effect.
“These results teach us a lot about the behavior of ice, and add more detail than is available by just looking at modern ice,” Willner told CNN.
Among the bleak news, there was also some good news about a process that scientists fear could cause rapid melting of the ice.
There are concerns that the collapse of the Thwaites Ice Shelves could create towering ice cliffs exposed to the ocean. These towering cliffs could easily become unstable and fall into the ocean, exposing higher cliffs behind them, with the process repeating over and over again.
However, computer modelling has shown that although this phenomenon is real, the chances of it occurring are lower than previously feared.
This does not mean that Thwaites is safe.
Scientists predict that the entire Thwaites Glacier and the Antarctic ice sheet behind it could disappear in the 23rd century. Even if humans quickly stop burning fossil fuels—which they are not doing now—it may be too late to save it.
As this phase of the ITGC project nears its end, scientists say more research is needed to learn more about this complex ice and understand whether its retreat is now irreversible.
“Despite the progress we’ve made, we still have deep uncertainty about the future,” said Eric Rignot, a glaciologist at the University of California, Irvine, and a member of the International Glaciology Institute. “I’m still very concerned that this part of Antarctica is already in a state of collapse.”
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