A team of researchers from the United States, the United Kingdom, Canada, and France recorded an unprecedented retreat of the Hektoria Glacier, located on the Antarctic Peninsula.
Between November and December 2022, the glacier lost more than eight kilometers of ice in just two months, at a rate ten times faster than previously observed in this type of ice mass.
The finding, published in the journal Nature Geoscience, constitutes a historic record in the monitoring of land-based glaciers.
A speed never before seen in terrestrial glaciers
Polar glaciers resting on rock typically retreat a few hundred meters per year. In the case of Hektoria, scientists calculated through satellite images, aerial flights, and altimetric data that the loss reached 800 meters per day.
“What is extraordinary is that it occurred with ice resting on the bedrock, not floating, and in just two months,” explained Etienne Berthier, glaciologist at the University of Toulouse and co-author of the study.
Why it matters: impact on sea level
Unlike floating ice, whose melting does not significantly alter sea level, the retreat of land-based glaciers directly contributes to the rise of the oceans.
Understanding how polar glaciers behave and what factors accelerate their retreat is key to more accurately predicting sea level rise, a phenomenon that threatens millions of people in coastal areas worldwide.
An analogy with the distant past
Never before has a retreat of this magnitude been recorded with modern observations. However, geological studies indicate that around 20,000 years ago, during the retreat of the ice cap that covered Scandinavia, there were periods with similar rates of ice loss, of several hundred meters per day.
This suggests that during periods of accelerated warming, extreme instabilities in polar masses can occur, with global consequences.
Factors explaining the retreat of Hektoria
Researchers attribute this phenomenon to two main factors:
- Flat coastal topography: small variations expose large ice surfaces to contact with the sea.
- Collapse of the Larsen B ice shelf in 2002: the disappearance of this gigantic ice barrier removed the “plug” that contained the glaciers in the area, accelerating their melting.
According to Berthier, the collapse of Larsen B and the record retreat of Hektoria are part of a “chain reaction” linked to global warming.
Global consequences of melting
The retreat of glaciers like Hektoria adds to other processes driving the rise in sea level:
- Warming of the oceans, which expand as their temperature increases.
- Melting of mountain glaciers in various regions of the planet.
- Melting of Greenland and Antarctica, which contribute enormous volumes of fresh water.
Currently, each of these factors contributes approximately one-third of the global sea level rise.
A wake-up call from Antarctica
The retreat of the Hektoria Glacier is a critical indicator of the vulnerability of polar masses to climate change.
Its study not only provides unprecedented data on glacier dynamics but also reinforces the urgency to reduce global greenhouse gas emissions to avoid even more extreme instability scenarios.
Antarctica, considered for centuries an immutable continent, is now revealed as a thermometer of the planet: what happens there anticipates transformations that will affect all of humanity.
