June 20, 2024

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Ocean water rushes miles under ‘Doomsday Glacier’ with potential dire effects on sea level rise

Ocean water rushes miles under ‘Doomsday Glacier’ with potential dire effects on sea level rise



CNN

Ocean water pushes miles down Doomsday Glacier in Antarctica That makes it more vulnerable to melting than previously thought, according to new research that used radar data from space to X-ray the important glacier.

When relatively warm, salty ocean water meets ice, it causes “forceful melting” beneath the glacier and can Means global sea level rise projections are underway According to the study published Monday in the Proceedings of the National Academy of Sciences.

Thwaites Glacier in West Antarctica – It is called the “Doomsday Glacier” because it contains… A collapse could lead to a catastrophic rise in sea levels – It is the largest glacier in the world and is approximately the size of the state of Florida. It is also the most vulnerable and unstable glacier in Antarctica, largely because the land on which it lies slopes downward, allowing ocean water to eat up its ice.

Thwaites, which already contributes 4% to global sea level rise, contains enough ice to raise sea levels by more than two feet. But because it also acts as a natural dam on the surrounding ice in West Antarctica, Scientists have estimated Its complete collapse could eventually cause sea levels to rise by about 10 feet — a disaster for the world’s coastal communities.

Several studies have pointed to Thwaites’ enormous weaknesses. Global warming, caused by humans burning fossil fuels, has left them behind Hanging by her nails According to a 2022 study.

This latest research adds a new and worrying factor to the predictions of her fate.

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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 image of the glacier. This allowed them to build a picture of changes to the ‘ground line’ of Thwaites Island, the point at which the glacier rises from the sea floor and becomes a floating ice shelf. Grounding lines are vital to the stability of ice sheets, and a major weakness in the Thwaites region, but have been difficult to study.

“In the past, we only had sparse data to look at this,” said Eric Rignot, a professor of Earth system sciences at the University of California, Irvine and co-author of the study. Stady. “In this new dataset, which is published daily and over several months, we have strong observations of what is happening.”

Eric Regnow/University of California, Irvine

A view of the tidal movement of Thwaites Glacier, West Antarctica, recorded by the Finnish commercial satellite mission ICEYE, based on images acquired on 11, 12 and 13 May 2023.

They observed seawater pushing under the glacier for several miles, then moving out again, following the daily rhythm of the tides. When the water flows, it is enough to “raise” the glacier’s surface by a few centimeters, Regno told CNN.

He suggested that the term “grounding zone” might be more appropriate than the grounding line, as it can move approximately 4 miles during a 12-hour tidal cycle, according to their research.

The speed of seawater, which moves large distances over a short period of time, increases the melting of glaciers because once the ice melts, fresh water is washed away and replaced by warmer seawater, Reno said.

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He added: “The large-scale and massive seawater intrusion will increase expectations of sea level rise from Antarctica.”

Ted Scambos, a glaciologist at the University of Colorado Boulder, who was not involved in the study, called the research “astonishing and important.”

“This result yields a process that has not yet been taken into account in models,” he told CNN. Although these results only apply to certain areas of the glacier, this may speed up the pace of ice loss in our projections.

James Smith, a marine geologist at the British Antarctic Survey, who was not involved in the study, said one uncertainty to be resolved is whether the rush of seawater under Thwaites is a new phenomenon or whether it has been significant but unknown for a long time.

“Either way, it’s clearly an important process that needs to be incorporated into ice sheet models,” he told CNN.

Noel Gormelin, professor of Earth observation at the University of Edinburgh, said the use of radar data in this study was interesting. “Ironically, by going into space, using our growing space capabilities, we learn a lot about this environment,” he told CNN.

Gormelin, who was not involved in the research, said there are still many unknowns about what the study results mean for Thwaites’ future. It’s also unclear how widespread this process is around Antarctica, “although it’s very likely this could be happening elsewhere as well,” he told CNN.

Antarctica, an isolated and complex continent, appears increasingly vulnerable to the climate crisis.

By analyzing satellite data and using climate models, they found that this record low “is unlikely to occur without the impact of climate change.”

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In a separate study, also published on Monday, researchers from the British Antarctic Survey looked at why this happens. Record low levels of sea ice surrounding Antarctica last year.

Steve Gibbs/Bass

Sea ice around Rothera Point, on Adelaide Island to the west of the Antarctic Peninsula.

Melting sea ice It does not directly affect sea level rise because It’s already floating, however It leaves coastal ice sheets and glaciers exposed to waves and warm ocean water, making them more vulnerable to melting and disintegrating.

The researchers also used climate models to predict the potential speed of recovery from this extreme sea ice loss, and found that even after two decades, not all of the ice will return.

“The impacts of Antarctic sea ice remaining low for more than twenty years will be profound, including on local and global weather,” Louise Syme, co-author of the BAS study, said in a statement.

These findings add to evidence over the past few years that the region faces a “permanent regime shift,” the authors wrote.