Scientists track rapid retreat of Antarctic glacier

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Cadman Glacier before and after the ice shelf collapse. The image on the left was taken in 2017 and shows the ice shelf. An image taken this month shows the disappearance of the ice shelf on the right. Credit: European Commission, European Space Agency, Copernicus Sentinel-2 data, Benjamin Wallis

Scientists warn that seemingly stable glaciers in the Antarctic could be “rapidly changing” and losing large amounts of ice due to warming oceans.

Their discovery was made by a research team led by glaciologist Benjamin Wallis of the University of Leeds, who used satellites to monitor the Cadman Glacier, which runs into Beascochea Bay on the West Antarctic Peninsula. The researchers have Published Their analysis suggests that “ocean warming will lead to rapid reactivation of sea ice-depleting glaciers on the West Antarctic Peninsula.” Natural relationships.

In the year Between November 2018 and May 2021, the glacier retreated eight kilometers. Ice shelf At the end of the glacier – the ice extended to the sea and on the sea floor in a place known as the landfall zone – it fell.

The ice shelf acts as a buffer, slowing the movement of ice into the sea.

Surrounded by warm ocean waters, scientists believe the ice shelf became thinner and landlocked, and the ice shelf could no longer withstand the glaciers.

As a result, the glacier’s rate of flow increased rapidly – doubling its speed – increasing the amount of ice that the glacier sent into the sea, known as glacier melt.

Scientists monitor the rapid retreat of the Antarctic ice sheet

A sea ice glacier in Antarctica. The image shows Antarctica, but not the Cadman Glacier. Credit: Professor Anna Hogg

Wallis said, “We were surprised at how quickly Cadman went from a stable glacier to a stable glacier where we see sudden deformation and massive ice loss.

“It was also curious that the glaciers on this part of the West Antarctic Peninsula did not respond in the same way, which could hold important lessons for how we can do better.” Climate change It continues to influence this important and emotional polar area.

“Our study brings together three decades of data, nine different satellite missions, and measurements from in-situ ocean surveys to understand the changes happening in Antarctica. All sensors tell us a different part of the story.”

According to the scientists, the Cadman Glacier is currently in a state of “significant dynamic disequilibrium”. The ice on the glacier continues to thin, losing about 20 meters per year in elevation. This is equivalent to the loss of the height of a five-story building each year.

And about 2.16 billion metric tons of ice is flowing from the Cadman Glacier into the ocean every year.

Why is Cadman Glacier so unstable?

Abnormally high ocean water temperatures in early 2018/19 are believed to have caused rapid dynamic changes in the Cadman Glacier system around the West Antarctic Peninsula.

Scientists monitor the rapid retreat of the Antarctic ice sheet

The mountainous and snowy coast of the Antarctic Peninsula. A sea ice glacier in Antarctica. The image shows Antarctica, but not the Cadman Glacier. Credit: Professor Anna Hogg

Analyzing historical satellite data, the scientists believe that warmer ocean waters have gradually thinned the ice shelf since the early 2000s and possibly the 1970s.

The warm water is not on the ocean, it is not taken deep in the ocean Water column. This warm water may have reached the ice shelf on the sea floor. As a result, the ice shelf begins to melt from the bottom up.

In the year In 2018/19, the ice shelf was so thin that it broke away from the inland zone and began to float, resulting in a slip anchor and allowing the Cadman Glacier to carry more ice into the seas.

But the science team still faced a big question. Why did the Cadman Glacier collapse when the neighboring Funk and Lever Glaciers remained relatively stable?

Sea ridges protect some glaciers

Analyzing subsurface ocean data, they believe that ridges or sills, a series of sea rocks at depths of 200m and 230m, act as a barrier to prevent warm water from reaching the glacier. Although they warn that the increase in ocean temperature will affect the protection of some glaciers.

Professor Michael Meredith, from the British Antarctic Survey and one of the authors of the paper, said: “We know that the ocean around Antarctica is warming rapidly and this poses a serious threat to the glaciers. Ice sheetConsequences of global sea level rise.

Scientists monitor the rapid retreat of the Antarctic ice sheet

Antarctic Peninsula mountains and glaciers above. A sea ice glacier in Antarctica. The image shows Antarctica, but not the Cadman Glacier. Credit: Professor Anna Hogg

“This new study shows that seemingly stable glaciers can change rapidly, become unstable without warning, then shrink and retreat significantly. This highlights the need for a comprehensive network of ocean observations around Antarctica, especially in regions near the glaciers. They are particularly difficult to make measurements.” ”

As the researchers write in the paper, what happened to the Cadman Glacier can be considered as an example of a “glaciological tipping point”, a system in a stable state can take one or two paths depending on the change in environmental parameters. .

In the year In 2018, the arrival of unusually warm ocean water caused the ice shelf to collapse. Reaching this peak has caused the Cadman Glacier to increase its ice flow by 28 percent in 13 months.

The researchers said other glaciers on the Antarctic Peninsula may be subject to similar sudden changes due to marine geology.

Additional information:
Benjamin Wallis, Ocean Warming Causes Rapid Activation of Sea Ice-Destroying Glaciers on the West Antarctic Peninsula; Natural relationships (2023) DOI: 10.1038/s41467-023-42970-4. www.nature.com/articles/s41467-023-42970-4

Presented by
University of Leeds


QuoteScientists Track Rapid Retreat of Antarctic Ice Sheets (2023, November 28) Retrieved November 28, 2023 from https://phys.org/news/2023-11-scientists-track-rapid-retreat-antarctic.html

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