“Antarctic Glacier’s Swift Collapse: A Wake-up Call for Ocean Monitoring”

A recent investigation led by glaciologist Benjamin Wallis has unveiled the disconcerting fragility of the Antarctic’s Cadman Glacier, which underwent rapid ice loss due to ocean warming. This revelation underscores the pressing need for comprehensive ocean monitoring and raises concerns about the vulnerability of other glaciers to similar abrupt transformations.

In a recent study conducted by a team led by glaciologist Benjamin Wallis at the University of Leeds, it has been observed that even glaciers in the Antarctic, initially deemed stable, can swiftly undergo significant ice loss in response to warmer ocean conditions. Utilizing satellite data, the researchers closely monitored the Cadman Glacier, situated in the Beascochea Bay area of the West Antarctic Peninsula, and detected substantial alterations.

Between November 2018 and May 2021, the glacier receded by a staggering eight kilometers as the ice shelf at its terminus, the grounding zone, collapsed. This ice shelf had been functioning as a stabilizing force, impeding the glacier’s movement toward the ocean. However, surrounded by progressively warmer ocean waters, the ice shelf thinned and eventually disengaged from the seafloor, losing its ability to restrain the glacier’s advance.

The consequence was an accelerated flow of the glacier, doubling its speed, and subsequently discharging more ice into the ocean through iceberg calving. Wallis commented on this development, noting the surprise at the rapid transition of Cadman Glacier from apparent stability to a state of significant ice loss.

Curiously, neighboring glaciers in the same region of the West Antarctic Peninsula did not exhibit similar responses, providing potential insights into how climate change impacts this critical polar region differently. Wallis emphasized the importance of amalgamating data from multiple sources, spanning three decades and nine satellite missions, alongside in-situ oceanographic measurements, to comprehend the evolving dynamics of Antarctica adequately.

Currently, the Cadman Glacier finds itself in a state of “substantial dynamic imbalance.” The ice continues to thin, losing elevation at a rate equivalent to a five-story building each year. An astounding 2.16 billion tonnes of ice are now entering the ocean annually from the Cadman Glacier, a disconcerting revelation documented in the scientific journal Nature Communications.

The unstable state of the Cadman Glacier can be attributed to unusually high ocean temperatures around the West Antarctic Peninsula in 2018/19. Historical satellite data suggests that warmer ocean waters had gradually eroded the glacier’s ice shelf since the early 2000s, possibly even dating back to the 1970s.

These warmer waters, though not visible at the ocean’s surface, existed deeper in the water column and likely reached the ice shelf, initiating bottom-up melting. By 2018/19, the ice shelf had become so thin that it disengaged from the grounding zone, allowing the Cadman Glacier to release more ice into the sea.

However, the puzzle remained: why did the Cadman Glacier collapse while neighboring glaciers remained relatively stable? An analysis of subsea oceanographic data suggests that subsea rock formations, known as ridges or sills at depths of 200 meters and 230 meters, acted as natural barriers, diverting warmer water away from the glaciers. Nonetheless, the researchers caution that increased ocean warming could jeopardize these protective ridges in the future.

Professor Michael Meredith from the British Antarctic Survey emphasizes the urgency of establishing a comprehensive ocean observing network around Antarctica, particularly in regions adjacent to glaciers that are challenging to monitor. He underscores the fact that stable glaciers can undergo rapid, destabilizing changes, underlining the need for proactive monitoring to mitigate the consequences of climate change.

In conclusion, the Cadman Glacier’s swift collapse serves as a stark example of a “glaciological tipping point” triggered by warm ocean water, leading to a significant increase in ice discharge. This revelation calls for heightened attention to the vulnerability of other Antarctic glaciers, especially in light of subsea geological factors that could precipitate similar sudden transformations.

This groundbreaking research was made possible through funding from the Natural Environment Research Council, the European Space Agency, the European Commission, and the National Science Foundation.

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More about Antarctic Glacier Collapse

• Nature Communications – “Ocean warming drives rapid dynamic activation of marine-terminating glacier on the west Antarctic Peninsula”
• University of Leeds – Benjamin Wallis
• British Antarctic Survey – Michael Meredith
• Natural Environment Research Council
• European Space Agency
• European Commission
• National Science Foundation