by Ocean water is pushing miles beneath Antarctica’s “Doomsday Glacier,” making it more vulnerable to melting than previously thought, according to new research that used radar data from space to X-ray of the critical glacier.
As the relatively warm, salty seawater alone hits the ice, it is causing “vigorous melting” under the glacier and could mean projected global sea level rise being underestimated, according to the study published Monday in the Proceedings of the National Academy of Sciences.
The Thwaites Glacier in West Antarctica – known as the “Doomsday Glacier” because it could cause a catastrophic rise in sea level – is the widest glacier in the world and about the size of Florida. It is also the most fragile and unstable glacier in Antarctica, largely because the land on which it sits is sloping down, allowing ocean waters to eat away at its ice.
Thwaites, which already contributes 4% to global sea level rise, holds enough ice to raise sea levels by more than 2 feet. But because it also acts as a natural dam for the surrounding ice in West Antarctica, scientists estimate that a total sea level rise could result in about 10 feet of sea level rise — a disaster for the world’s coastal communities.
Many studies have drawn attention to Thwaites’ enormous vulnerabilities. Global warming, driven by humans burning fossil fuels, hangs “on its finger,” according to a 2022 study.
This latest research adds a scary new factor to predictions about his fate.
A team of glaciologists – led by scientists from the University of California, Irvine – used high-resolution satellite radar data, collected between March and June last year, to create an X-ray of the glacier. This allowed them to take a picture of the changes in Thwaites’ “landing line”, the point at which the glacier rises from the seabed and becomes a floating ice shelf. Ground lines are critical to the stability of the ice sheets, and are a key point of vulnerability for Thwaites, but they have been difficult to study.
“In the past, we only had sporadic data to look at this,” said Eric Rignot, professor of Earth system science at the University of California at Irvine and co-author of the study. “In this new data set, which is running every day and over several months, we have solid views of what’s going on.”
They saw sea water pushing under the glacier over thousands of miles, and then moving out again, following the daily rhythm of the tide. When the water flows in, it is enough to “jack up” the surface of the glacier by centimeters, Rignot told CNN.
He suggested that the term “terrestrial zone” might be more appropriate than the landline, as it can move nearly 4 miles over a 12-hour tidal cycle, according to their research.
The speed of seawater, which moves significant distances over a short period of time, increases glacier melting because as soon as the ice melts, fresh water is washed out and replaced by warmer seawater, Rignot said.
“This process of widespread, massive seawater intrusion will increase the projections of sea level rise from Antarctica,” he said.
Ted Scambos, a glaciologist at the University of Colorado Boulder, who was not involved in the study, called the research “interesting and important.”
“This result provides a process that, as yet, has not been included in models,” he told CNN. And while these results only apply to certain areas of the glacier, he said, “this could accelerate the pace of ice loss in our forecasts.”
One uncertainty that remains to be resolved is whether the seawater rush under Thwaites is a new phenomenon or whether it has been significant but unknown for a long time, said James Smith, a marine geologist at the British Antarctic Survey, who was not involved in the study.
“Either way, it’s clearly an important process that needs to be incorporated into ice sheet models,” he told CNN.
Noel Gourmelen, professor of Earth observation at the University of Edinburgh, said the use of radar data for this study was interesting. “Ironically, it’s by going to space, using our increasing satellite capabilities, that we’re learning a lot more about this environment,” he told CNN.
There are still many unknowns about what the study’s results mean for Thwaites’ future, said Gourmelen, who was not involved in the research. It’s also not clear how widespread this process is around Antarctica, he told CNN, “although this is probably happening elsewhere as well.”
Regime change
Antarctica, a remote and complex continent, appears to be increasingly vulnerable to the climate crisis.
Analyzing satellite data and using climate models, they found that the record number “would likely have occurred without the impact of climate change”.
In a separate study, also published on Monday, researchers from the British Antarctic Survey looked at the reasons for the lowest levels of sea ice around Antarctica last year.
Melting sea ice does not directly contribute to sea level rise because it is already floating, but it leaves coastal ice sheets and glaciers exposed to waves and warm sea waters, making them vulnerable to melting and breaking up .
The researchers also used climate models to predict the expected speed of recovery from such large sea ice losses and found that even after twenty years, not all of the ice will return.
“Antarctic sea ice remaining low for more than two decades would have a profound impact, including on local and global weather,” Louise Sime, co-author of the BAS study, said in a statement.
The findings add to evidence in recent years that “sustainable regime change is in store for the region,” the authors wrote.
For more CNN news and newsletters create an account at CNN.com
