Researchers report that Antarctica’s Hektoria Glacier — about 115 square miles — lost nearly half its ice between November 2022 and January 2023, retreating roughly 5 miles (≈8 km). A University of Colorado Boulder-led study in Nature Geoscience found Hektoria sat on a flat ice plain, went afloat, and then fractured rapidly as ocean forces met surface cracks, triggering massive calving. The collapse, discovered while studying Larsen B, produced seismic “glacier earthquakes” and highlights that similar bed topography under larger glaciers could enable equally fast retreat and accelerate sea-level rise.
Antarctica’s Hektoria Glacier Lost Nearly Half Its Ice in Two Months — A Warning for the Continent
Researchers report that Antarctica’s Hektoria Glacier — about 115 square miles — lost nearly half its ice between November 2022 and January 2023, retreating roughly 5 miles (≈8 km). A University of Colorado Boulder-led study in Nature Geoscience found Hektoria sat on a flat ice plain, went afloat, and then fractured rapidly as ocean forces met surface cracks, triggering massive calving. The collapse, discovered while studying Larsen B, produced seismic “glacier earthquakes” and highlights that similar bed topography under larger glaciers could enable equally fast retreat and accelerate sea-level rise.
02:28, 06.11.2025Environment
Antarctica’s Hektoria Glacier Lost Nearly Half Its Ice in Two Months
Hektoria Glacier, a modestly sized glacier in Antarctica covering about 115 square miles (roughly the size of Philadelphia), lost nearly half its ice between November 2022 and January 2023. That retreat is equivalent to roughly 5 miles (≈8 km) of ice in just two months — a rate that surprised researchers and raises concern for other Antarctic glaciers.
A University of Colorado Boulder-led study published in Nature Geoscience explains how that rapid collapse unfolded and why it may signal broader vulnerability across the continent. The finding was made while researchers were studying the nearby Larsen B region, not as part of a targeted Hektoria investigation.
“Hektoria’s retreat is a bit of a shock — this kind of lightning-fast retreat really changes what’s possible for other, larger glaciers on the continent,” said Ted Scambos, a senior research scientist at the Cooperative Institute for Research in Environmental Sciences (CIRES). He warned that if similar conditions occur elsewhere, Antarctic contributions to sea-level rise could accelerate substantially.
Most glaciers move slowly, advancing a few feet to a few hundred feet per year. Hektoria moved far faster. Researchers discovered the record-speed retreat while analyzing satellite imagery and seismic records gathered during a separate study of Larsen B. Naomi Ochwat, the study's lead author and a CIRES postdoctoral researcher, noticed the rapid breakup in the combined satellite record.
“If we only had one image every few months, we might have missed it entirely,” Ochwat said. “By combining multiple satellites, we could actually watch this glacier retreat two and a half kilometers in just two days.”
Unlike many tidewater glaciers that sit on sloping bedrock, Hektoria overlies a broad, flat area of bedrock called an ice plain. Past research indicates glaciers on similar ice plains retreated hundreds of meters per day 15,000–19,000 years ago — a behavior that helped explain Hektoria’s sudden collapse.
As Hektoria pulled back, parts of the glacier rose off the seafloor and began to float — a transition scientists call “going afloat.” Once afloat, ocean currents and waves undermined the ice from below while surface stresses opened fractures from above. When these fractures connected, enormous sections of ice calved away in rapid succession, producing a chain reaction that removed nearly half the glacier’s ice.
Seismic instruments recorded so-called “glacier earthquakes” — vibrations caused by large ice sections breaking and striking the sea — confirming that Hektoria had been grounded on bedrock before the collapse and that the lost ice directly contributed to sea-level rise.
Researchers note that ice-plain topography exists beneath several larger Antarctic glaciers, some of which store enough ice to raise global sea levels substantially if they were to retreat similarly fast. Hektoria therefore serves as a dramatic and timely example of how quickly even long-frozen parts of Antarctica can become vulnerable.
Author: Jennifer Gray is a weather and climate writer for Weather.com and has covered major weather and climate stories for more than two decades.