How Antartic Glaciers Can Switch Rapidly and Lose Significantly More Ice in a Short Period of Time

Tuesday - December 5 2023, 10:48 UTC - 11 months ago

Scientists have found that even seemingly stable glaciers in the Antarctic can "switch very rapidly" and lose large quantities of ice due to warmer oceans. Significant changes in the Cadman Glacier, located in the Beascochea Bay area of the West Antarctic Peninsula, have been observed. The ice shelf was no longer able to hold back the glacier causing it to move rapidly and increasing the amount of ice discharged into the sea. Unusually high ocean water temperatures in early 2018/19 around the west Antarctic peninsula are believed to have triggered the rapid dynamic change on the glacier.

Scientists have found that even seemingly stable glaciers in the Antarctic can "switch very rapidly" and lose large quantities of ice as a result of warmer oceans. This alert follows a study by a team led by glaciologist Benjamin Wallis from the University of Leeds. Using satellite data, the team observed significant changes in the Cadman Glacier, located in the Beascochea Bay area of the West Antarctic Peninsula .

Between November 2018 and May 2021, the glacier retreated eight kilometers as the ice shelf at the end of the glacier — where ice extends out into the sea and is anchored onto the sea floor at what is known as the grounding zone — collapsed. The ice shelf would have acted as a buttress, slowing the movement of the glacier towards the sea. Surrounded by warmer ocean waters, the scientists believe the ice shelf thinned and became ungrounded, and the ice shelf was no longer able to hold back the glacier .

As a result, the speed at which the glacier was flowing rapidly accelerated — doubling its speed — increasing the amount of ice it discharges into the sea as icebergs, through a process known as iceberg calving.Wallis said: "We were surprised to see the speed at which Cadman went from being an apparently stable glacier to one where we see sudden deterioration and significant ice loss."What was also curious was that the neighboring glaciers on this part of the west Antarctic Peninsula did not react in the same way, which may hold important lessons for the way we can better project how climate change will continue to affect this important and sensitive polar region .

"Our study brought together data from three decades, nine different satellite missions, and in-situ oceanographic measurements to understand the changes happening in Antarctica. This demonstrates how important it is to have long-term monitoring of the Earth's polar regions with a range of sensors which all tell us a different piece of the story."According to the scientists, the Cadman Glacier is now in a state of "substantial dynamic imbalance" .

The ice on the glacier has continued to thin, with elevation being lost at a rate of around 20 meters a year. That is equivalent to a loss in height of a five-story building each year. And around 2.16 billion tonnes of ice are draining from the Cadman Glacier into the ocean each year. The researchers have published their analysis — Ocean warming drives rapid dynamic activation of marine-terminating glacier on the west Antarctic Peninsula — in the scientific journal Nature Communications .

Unusually high ocean water temperatures in early 2018/19 around the west Antarctic peninsula are believed to have triggered the rapid dynamic change on the Cadman Glacier system. By analyzing historic satellite data, the scientists believe warmer ocean waters gradually thinned the glacier's ice shelf from the early 2000s and possibly since the 1970s.The warmer water was not carried on the surface of the ocean but deep in the water column .

This warmer water may have reached the ice shelf where it is ground by the glacier through a process called sub-shelf melting.