It's on its way to being a fjord, not a glacier.
On the eastern edge of Antarctica, a glacier that had quietly endured for a decade suddenly surrendered to forces set in motion twenty years prior. Between January 2022 and April 2023, Hektoria Glacier retreated fifteen miles in fifteen months — a modern record for grounded ice loss, the kind whose disappearance raises seas rather than merely reshapes coastlines. The collapse traces back to 2002, when the Larsen B ice shelf shattered and removed the protective barrier that had held Hektoria in place, leaving it to survive on borrowed time and borrowed ice. What Hektoria leaves behind is not merely a retreating glacier but a parable about hidden vulnerability, delayed consequence, and the compounding costs of a warming world.
- Hektoria Glacier retreated fifteen miles in fifteen months — a pace so extreme it set a modern record for grounded ice loss, compressing decades of expected change into a single austral cycle.
- The collapse was not sudden but inherited: the 2002 disintegration of the Larsen B ice shelf removed the glacier's protective dam, and a decade of apparent stability was revealed as a fragile illusion propped up by temporary sea ice.
- In January 2022, powerful ocean swells destroyed that last support, triggering a cascade — floating ice tongues calved away in city-block-sized chunks, and seawater began lifting grounded ice off bedrock through buoyancy-driven forces that accelerated catastrophic detachment.
- Scientists now warn that Hektoria is a preview: as warming strips protective ice tongues from larger Antarctic glaciers, the same buoyancy-driven collapse could threaten ice streams whose loss would register in sea levels felt by coastal populations worldwide.
- The most violent phase appears to be over, but the glacier has lost so much mass it is, in one researcher's words, 'on its way to being a fjord, not a glacier' — a transformation that cannot be undone.
On the eastern Antarctic Peninsula, Hektoria Glacier came apart with startling speed. Between January 2022 and April 2023, it retreated fifteen miles — a distance that would normally unfold over decades, compressed into fifteen months. Scientists analyzing satellite imagery and laser measurements from space confirmed they were witnessing a modern record for the loss of grounded ice: the kind anchored to bedrock that raises sea levels directly when it enters the ocean.
The collapse had roots two decades old. In 2002, the Larsen B ice shelf — a massive floating platform that had buttressed Hektoria like a dam — suddenly shattered. Without it, the glacier began a slow decline. A brief reprieve came in 2011, when sea ice forming near the glacier's terminus provided temporary support, allowing Hektoria to appear, from a distance, to be recovering. That appearance was deceptive. Beneath the surface, the glacier continued to thin, its vulnerability masked by frozen seawater.
In January 2022, powerful ocean swells broke apart that last support. What followed was a cascade of failure. The glacier's floating ice tongue fractured in repeated calving events through the austral summer, retreating roughly ten miles before winter brought a surface pause — though satellite data showed it was still thinning beneath. When spring arrived, the deeper unraveling began. Bedrock beneath Hektoria is broad and flat, allowing seawater to flow underneath during high tides and lift sections of ice off the ground. When ice thins enough, this buoyancy-driven process can trigger sudden, catastrophic detachment. Hektoria lost another five miles in what became, in retrospect, the collapse's second and more devastating act.
Glaciologist Naomi Ochwat of the University of Innsbruck, who led the study, recognized Hektoria not as an isolated event but as a warning. As temperatures rise across the Antarctic Peninsula, more glaciers are losing their protective ice tongues and becoming exposed to the same buoyancy-driven forces. If those forces were to reach Antarctica's massive ice streams, the consequences for global sea levels would be profound.
The most violent phase appears to be over. The glacier has shed so much mass and dropped so much in elevation that it can no longer sustain its former pace of loss. Co-author Ted Scambos of the University of Colorado Boulder offered a stark summary: 'It's on its way to being a fjord, not a glacier.' New satellite missions may help detect similar vulnerabilities elsewhere before they cascade — but the window for prevention, if it ever truly existed, has likely already closed.
On the eastern Antarctic Peninsula, a glacier that had seemed stable for a decade suddenly came apart. Between January 2022 and April 2023, Hektoria Glacier retreated fifteen miles—a distance that would normally take decades to cover, compressed into fifteen months. Scientists studying satellite imagery and laser measurements from space concluded they were witnessing something rare: a modern record for the loss of grounded ice, the kind anchored to bedrock that directly raises sea levels when it melts into the ocean.
The collapse did not happen in isolation. Hektoria's fate was sealed two decades earlier, in 2002, when the Larsen B ice shelf—a massive floating platform of ice that had buttressed the glacier like a dam—suddenly shattered and disappeared. Without that protective barrier, Hektoria began a slow decline, thinning and retreating year after year. But in 2011, something seemed to stabilize the glacier. Sea ice that formed and froze in the embayment near its terminus provided temporary support, allowing Hektoria to advance slightly and appear, at least from a distance, to be recovering. That appearance was deceptive. Beneath the surface, the glacier continued to thin, a vulnerability masked by the temporary prop of frozen seawater.
In January 2022, that support vanished. Powerful ocean swells broke apart the landfast sea ice, removing the only thing holding Hektoria in place. What followed was a cascade of failure. Through the austral summer, the glacier's floating ice tongue—the section extending into open water—began breaking apart in repeated calving events, chunks the size of city blocks splitting away and drifting into the Southern Ocean. By the end of that summer season, the glacier had retreated roughly ten miles. It paused during the winter months, but satellite laser measurements showed it was still thinning, still weakening, even as it appeared motionless from above.
When spring arrived, the real unraveling began. Researchers analyzing seismic data detected earthquakes beneath the glacier and realized the remaining ice was still grounded—still resting on bedrock. But the bedrock beneath Hektoria is not steep or jagged. It is broad and relatively flat, a terrain that allows seawater to flow underneath during high tides, lifting sections of ice off the ground like a hydraulic jack. When ice becomes thin enough, this process—called buoyancy-driven calving—can trigger catastrophic failure. Large portions suddenly detach and break away all at once. This is what happened to Hektoria in its second phase of collapse. The glacier lost another five miles in length, and the retreat that had seemed dramatic in summer became, in retrospect, merely the opening act.
Naomi Ochwat, a glaciologist at the University of Innsbruck who led the study, and her colleagues recognized that Hektoria's collapse was not an isolated incident but a warning. As temperatures rise around the Antarctic Peninsula, more glaciers are losing their protective ice tongues and becoming what scientists call tidewater glaciers—glaciers whose termini rest directly on the seabed, exposed to the same buoyancy-driven forces that destroyed Hektoria. This type of glacier is common in Alaska and Greenland as well. If the same processes that unraveled a relatively small glacier like Hektoria were to affect Antarctica's massive ice streams, the consequences for global sea levels would be profound.
The most violent phase of Hektoria's collapse appears to be over. Scientists expect the glacier to continue retreating, but more slowly now, as it loses elevation and mass. Ted Scambos, a senior research scientist at the University of Colorado Boulder and co-author of the study, offered a stark assessment: the glacier has shed so much ice and dropped so much in elevation that it cannot sustain its former pace of loss. "It's on its way to being a fjord, not a glacier," he said. New satellite technologies—NASA's NISAR and SWOT missions, which can measure ice movement to the centimeter and track detailed changes in water surfaces—may help scientists detect similar vulnerabilities in other glaciers before they collapse. But the window for prevention, if it ever existed, has likely already closed.
Notable Quotes
The glacier has lost so much elevation and mass that it simply can't continue to maintain the same output.— Ted Scambos, University of Colorado Boulder
New satellite technologies could significantly improve scientists' understanding of rapid glacier retreat.— Naomi Ochwat, University of Innsbruck
The Hearth Conversation Another angle on the story
Why does it matter that this glacier lost grounded ice specifically, rather than just the floating part?
Grounded ice is sitting on land or bedrock. When it melts or breaks away, it adds water to the ocean. Floating ice is already displacing water, so it doesn't raise sea level when it goes. Hektoria lost both, which is why scientists are alarmed.
The glacier seemed stable in 2011. What changed?
The sea ice that was propping it up broke apart in January 2022 after a storm. But that's almost a symptom, not the disease. The real problem was that the glacier had been thinning invisibly for years. The sea ice was just masking how vulnerable it had become.
How does buoyancy-driven calving actually work?
Imagine ice resting on a flat seabed. When the tide comes in, seawater flows underneath and lifts the ice slightly. If the ice is thin enough, that lift can be enough to break it free. Once a piece detaches, the whole system becomes unstable.
Is Hektoria unusual, or are other glaciers at risk?
Hektoria is small. What worries scientists is that larger glaciers in Antarctica and Greenland are losing their protective ice shelves and becoming tidewater glaciers too. If the same process hits a glacier ten times bigger, the sea level rise would be catastrophic.
Can we predict when the next one will collapse?
That's what the new satellites are for. NISAR can measure ice movement to the centimeter. If we can see thinning and structural weakness early enough, we might catch the next one before it fails. But Hektoria happened so fast that even good data couldn't have stopped it.