In 2023, Hektoria Glacier on Antarctica's Eastern Peninsula retreated eight kilometers in just two months, marking the fastest such event recorded. Nearly half of the glacier broke apart due to its position over a flat underwater bedrock. The discovery, detailed in a new study, highlights vulnerabilities in other Antarctic ice features.
Researchers from the University of Colorado Boulder have documented an unprecedented retreat of Hektoria Glacier, a tidewater glacier on Antarctica's Eastern Peninsula. Between 2023 and early 2024, the glacier lost about eight kilometers of ice in 60 days, with nearly half of its 115-square-mile expanse—roughly the size of Philadelphia—calving into the sea.
The rapid collapse was triggered by the glacier's location over an ice plain, a flat stretch of bedrock below sea level. As the ice thinned, large sections lifted off the seabed and began floating, exposing them to ocean forces that widened cracks from base to surface. This chain reaction led to extensive calving in weeks. Satellite data and seismic instruments captured the event in near real time, detecting glacier earthquakes that confirmed the ice had been grounded before lifting.
The team, led by Naomi Ochwat, a CIRES postdoctoral researcher, initially reviewed the area while studying sea ice detachment linked to a 2002 ice shelf breakup. Unexpectedly, satellite images revealed the dramatic retreat. "When we flew over Hektoria in early 2024, I couldn't believe the vastness of the area that had collapsed," Ochwat said. Frequent satellite observations allowed precise reconstruction: "If we only had one image every three months, we might not be able to tell you that the glacier lost two and a half kilometers in two days," she added.
Historical evidence shows similar ice plains enabled rapid retreats 15,000 to 19,000 years ago, sometimes hundreds of meters per day. CIRES Senior Research Scientist Ted Scambos noted the implications: "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." Such events could accelerate sea level rise if replicated elsewhere, as ice plains underlie many Antarctic glaciers. The findings appear in Nature Geoscience.
