In late 2022, scientists observed a startling event in Antarctica: the rapid retreat of Hektoria Glacier by more than 8 kilometers (5 miles) within just two months. This sudden and dramatic change left researchers puzzled, prompting investigations into the underlying causes. A new study now offers a potential explanation, suggesting that Hektoria Glacier may represent the first modern example of a rapid destabilization process occurring when the front of a glacier resting on the seabed suddenly destabilizes. This phenomenon could have significant implications for the future of Antarctic ice loss and global sea-level rise if it occurs elsewhere on the continent. However, not all experts agree with the study’s conclusions, sparking a scientific debate about the glacier’s behavior and the mechanisms driving its retreat.
Hektoria Glacier is located on the Antarctic Peninsula, a region known for its sensitivity to climate change. Satellite data confirmed that between January 2022 and March 2023, the glacier’s front retreated by a staggering 25 kilometers (16 miles). While the scale of this retreat is undisputed, understanding exactly what caused such rapid ice loss has proven challenging. Naomi Ochwat, the lead author of the study and a researcher affiliated with the University of Colorado Boulder and the University of Innsbruck, likens investigating the glacier’s retreat to solving a “whodunnit” mystery.
The story of Hektoria’s recent changes begins with the collapse of the Larsen B ice shelf in 2002. Larsen B was a vast ice shelf, about 3,250 square kilometers in size—comparable to the combined area of English counties such as Cambridgeshire or Gloucestershire—that acted as a natural dam holding back glaciers like Hektoria. When Larsen B disintegrated, the glaciers it restrained began to accelerate and thin. However, the area left behind by the collapsed ice shelf eventually filled with sea ice that was “fastened” to the seabed, providing some temporary stabilization to Hektoria.
This relative calm lasted until early 2022 when the sea ice broke up, triggering further loss of floating ice from Hektoria’s front. Large, flat-topped icebergs calved from the glacier, which is a natural process in glacier dynamics, albeit one accelerated by human-induced climate change. The resulting ice loss caused the glacier to speed up and thin further. While such iceberg calving and retreat are common in ice shelves, the new study argues that what happened in late 2022 was unique because the glacier’s front was grounded—resting on the seabed—rather than floating.
If the glacier’s front was indeed grounded, the retreat rate observed—8.2 kilometers in just two months—would be nearly ten times faster than any previously recorded for grounded glaciers. This rapid retreat is attributed to an ice plain—a relatively flat area of bedrock beneath the glacier—where upward forces from ocean water could lift the thinning ice almost simultaneously. This lifting would cause large sections of ice to break off suddenly, accelerating retreat.
Adrian Luckman, co-author of the study and professor of geography at Swansea University, emphasizes the significance of this finding. He notes that glaciers typically do not retreat this quickly, and while the specific conditions at Hektoria may be unusual, this event could foreshadow what might happen elsewhere in Antarctica where glaciers lightly rest on the seabed and where sea ice no longer provides stabilization.
The possibility that this process has never been observed before in modern times adds to the study’s intrigue. Geological markings on the seafloor suggest that similar rapid ice losses may have occurred in Earth’s past, implying that understanding this mechanism could be crucial for predicting future ice sheet behavior. Ochwat highlights the broader implications, warning that if such rapid retreat occurs in larger glaciers, such as Thwaites Glacier—often called the “doomsday” glacier due to its potential to raise global sea levels by 65 centimeters (26 inches) if it were to melt completely—the impact on sea-level rise could be substantial.
Despite the compelling narrative, other scientists are cautious and have raised questions about the study’s interpretation, particularly regarding the exact position of the glacier’s grounding line—the boundary where the glacier detaches from the seabed and begins to float. Determining the grounding line’s location is critical because it affects how we interpret the glacier’s behavior. If Hektoria’s front was floating rather than grounded, then the rapid retreat would be categorized as iceberg calving from a floating ice shelf