Extract from ABC News
In short
The Hektoria Glacier on the Antarctic Peninsula is roughly 300 square kilometres.
Between January 2022 and March 2023, it retreated by 25 kilometres, including eight kilometres in two months.
What's next?
The findings could have consequences for much larger glaciers in Antarctica, which have the potential to significantly raise sea levels if they melt.
Antarctic scientists have documented the fastest retreat of a glacier in modern history, after it lost eight kilometres of ice in just two months, according to a new report.
The Hektoria Glacier on the eastern Antarctic Peninsula is roughly 300 square kilometres — about 10 times larger than the City of Sydney local government area.
International researchers, led by the University of Colorado Boulder, analysed satellite images and seismic data to investigate how and why the glacier rapidly lost ice.
A glacier "retreats" when it melts or erodes faster than it gains new ice, causing the front of the glacier to move backwards.
A report on their study, published in the journal Nature Geoscience, shows the glacier shrank 25km between January 2022 and March 2023.
Scientists said a similar retreat on larger glaciers would have "catastrophic" impacts. (Supplied: Naomi Ochwat)
This included a retreat of 8km between November and December 2022 — an unprecedented rate in the modern glaciological record.
"Hektoria Glacier is small by Antarctic standards … but a similar rapid retreat on larger Antarctic glaciers could have catastrophic implications for global sea level rise," the university said in a media release.
Glacier's rapid retreat occurred after collapse of ice shelf
Hektoria is one of several glaciers that fed into the Larsen B ice shelf before its collapse in 2002.
Without the ice shelf's buttressing effect, those glaciers retreated at an accelerated rate for about a decade, until sea ice fastened along the coast and slowed their pace.
Timelapse of Hektoria Glacier from November 2021 to July 2025. (Supplied: Nature Geoscience)
But in 2022, the fastened sea ice broke away, which subsequently caused the glaciers to retreat at an even faster speed, particularly during the summer months.
The report said Hektoria's "extraordinary retreat" was linked to its positioning over an "ice plain" — a flat area where the glacier was only "lightly grounded".
This, according to the researchers, caused a large part of the glacier to become buoyant, allowing chunks to break off into the ocean as icebergs.
"Hence, we conclude that in this case, retreat primarily resulted from an ice plain calving process, rather than atmospheric or oceanic conditions as suggested previously," the report stated.
"This implies that marine-terminating glaciers with ice plain bed geometry can be easily destabilised."
The report noted that ice plains have been detected in other parts of Antarctica, including the Ross Ice Shelf and the so-called "doomsday" Thwaites Glacier.
"Therefore, it is imperative to document the bedrock geometry beneath the glaciers around Antarctica to evaluate the potential for this type of instability to occur, and incorporate rapid buoyancy-driven retreat in models predicting the fate of the Antarctic ice sheet."
Changes like those in 'warmer' areas
Poul Christoffersen is a glaciologist at the Institute for Marine and Antarctic Studies at the University of Tasmania.
While he was not involved in the study, he said the results were significant.
A glacier "retreats" when it melts or erodes faster than it gains new ice, causing the front of the glacier to move backwards. (Reuters: Natalie Thomas)
"It is definitely or unarguably a very fast retreat that they're documenting,"Professor Christoffersen said.
"It's also a retreat that is a large proportion of the size of [this glacier] — that's also very clear.
"To have a glacier cut in half by size, it's extremely uncommon."
He said the changes observed with the Hektoria Glacier were reminiscent of those seen in Greenland, a region not as cold as Antarctica.
"Some people call that the 'Arctic-ification' or 'Greenland-ification' of Antarctica, meaning that the glaciers are showing signs or characteristics of glaciers elsewhere on the Earth that are typically warmer."
He said the study also corroborated previous observations suggesting the rapid retreat of glaciers thousands of years ago.
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