Research has shown that the Hector Glacier retreated an astonishing eight kilometers in just two months, which is an unprecedented case among all known glaciers in Antarctica.
This rapid melting was made possible by the unique subglacial topography, which creates conditions for its abrupt disintegration.
According to a publication in the journal Nature Geoscience, during November and December 2022, the glacier lost mass at a rate of up to half a mile per day. The cause of this record was the flat seabed, allowing the glacier to temporarily "float," which subsequently led to its breaking apart into large chunks.
If scientists had conducted observations with longer intervals, they might have missed the fact that the glacier lost about two and a half kilometers of mass in just two days.
Under the Hector Glacier lies a nearly flat area below sea level, where the ice partially contacts the seabed. This makes it particularly vulnerable: even slight thinning can lead to its sliding and loss of stability.
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When the ice thickness dropped to a critical level, the forces of gravity and buoyancy completed the destruction process. The glacier literally "floated" and cracked, forming numerous icebergs. At the same time, seismic stations recorded six glacial earthquakes — a clear sign of a large-scale collapse.
Satellite data indicate a sixfold increase in ice flow and thinning of its surface by approximately 80 meters per year. Uniquely, this process was not caused by rising ocean temperatures or intense surface melting. The main factor was the disappearance of seasonal fast ice, which previously held back the movement of ice and dampened wave oscillations.
Scientists compare the event to the collapse of the Larsen Ice Shelf in 2002, after which neighboring glaciers also began to move rapidly and thin significantly.
Despite the fact that Hector is a relatively small glacier, its behavior may serve as a warning sign. Flat subglacial plains are also found beneath larger Antarctic glaciers, indicating the possibility of similar "buoyancy bursts" that could significantly accelerate global sea level rise.
"If similar conditions exist beneath other glaciers, we may see sea level rise much sooner than existing models predict," comments Ted Scambos, a senior researcher at CIRES and one of the authors of the study.
Researchers continue to analyze satellite and seismic data to identify other areas with similar geometry. These areas are considered "early warning points": even slight thinning of ice in them can lead to sudden floating and collapse of glaciers.
The authors of the study emphasize that climate models must account for not only gradual melting processes but also abrupt episodes when a glacier loses support and collapses within days. Such events could significantly alter projections for global ocean level rise for decades to come.
