One Glacier's 'Out of This World' Retreat Might Have Set a Modern Record. Now, Scientists Pieced Together What Happened

New research finds that Hektoria, a grounded glacier in Antarctica, shrank with astounding speed in 2022 and 2023

Mary Randolph - Staff Contributor

November 7, 2025

A new study suggests the Hektoria Glacier, seen here in 2024, shrank by 16 miles between January 2022 and March 2023—and five miles in November and December 2022 alone. Naomi Ochwat

Researchers have uncovered an unprecedented change in a glacier, a new study suggests, and the group of scientists behind the work made the discovery by accident.

The team had been examining sea ice data from a bay in Antarctica for another study, when they noticed that one of its glaciers, called Hektoria, had shrunk rapidly in 2022.

“I realized that, OK, something special is going on here,” says Naomi Ochwat, the study’s lead author and a glacier researcher at the University of Colorado Boulder, to CNN’s Laura Paddison.

Hektoria is a grounded glacier, which means it’s attached to the seabed rather than floating entirely in water. Typically, grounded glaciers shrink by less than 1,000 feet each year, reports ABC News’ Julia Jacobo.

But Hektoria retreated by five miles in November and December 2022 alone, according to the study, published Monday in Nature Geoscience. Between January 2022 and March 2023, the glacier retreated 16 miles—more than the entire length of Manhattan.

“The numbers are incredibly out of this world, much higher than anything we have been able to observe,” says Mathieu Morlighem, a glaciologist at Dartmouth College who was not involved in the study, to Science’s Hannah Richter.

Did you know? Glacial calving reveals new ecosystems

This year, a Chicago-sized iceberg broke off, or calved, from the Antarctic Peninsula. Researchers working nearby changed their plans so that they could send a remotely operated vehicle to the newly accessible seafloor. They captured photos of sponges, anemones, snails, fish, jellyfish and octopuses.

Though glaciers breaking up or retreating is not uncommon, especially as the planet continues to warm, the researchers say this rate of shrinkage for a grounded glacier is unprecedented in the modern record. This staggering scale of retreat mirrors the melting seen during a period of warming that ended the last Ice Age.

To see this occur for the first time in modern history, says Ted Scambos, a study co-author and senior research scientist at the University of Colorado Boulder, to CNN, could be a warning signal for the shrinkage of larger glaciers, which could have worldwide impacts as they retreat. As glaciers go, Hektoria was already rather little.

“It’s a smaller cousin to some truly gigantic—I mean size of the island of Britain—glaciers in Antarctica that could conceivably go through the same process, as this whole evolution of the ice sheets on Earth evolves with global warming,” Scambos adds.

Animation: The fastest glacier retreat in modern history

Using years of satellite images, the researchers pieced together the story of Hektoria’s retreat. First, in 2011, the bay had filled with “fast ice” that was fastened to land and stabilized the glacier, allowing it to extend and form an “ice tongue” that was floating and not grounded to the seabed.

Storms sent waves into the bay in January 2022, breaking up the fast ice and leaving the glacier with less support. In the coming months, Hektoria’s floating section broke up into icebergs that drifted away.

As the glacier rapidly thinned, its ice became more buoyant and rose up from the ice plain beneath it—a flat section of bedrock that lies below sea level. This let ocean water flow in between the ice and the rock. The water filled crevasses in the glacier and prompted calving, where slabs of ice broke off, exposing the glacier behind it to more pressure.

Scambos tells CNN the process is similar to “dominoes toppling backwards, their feet slipping out from under them, one after the other.”

Thwaites Glacier in West Antarctica currently accounts for about 4 percent of global sea level rise annually. James Yungel via Wikimedia Commons

Though the science is clear on the rate of shrinkage that Hektoria underwent, assessing just how grounded the glacier was proves more complicated. Because it’s difficult to judge the exact point where the glacier attached to the seabed, some scientists are unsure if this shrinkage was actually unprecedented. Had the glacier been grounded farther inland than the team suggests, more of its ice would have been floating, and its retreat would have been less rare.

“If this section of the ice sheet was in fact floating [rather than resting on the seabed], the punchline would instead be that icebergs calved from an ice shelf, which is much less unusual behavior,” says Christine Batchelor, a physical geographer at Newcastle University in England who was not involved with the work, to Mark Poynting at BBC News.

Scientists agree, though, that this process was quickened by global warming, which led to the ice break-offs that destabilized Hektoria in the first place, per CNN.

“While we disagree about the process driving this change at Hektoria, we are in absolute agreement that the changes in the polar regions are scarily rapid, quicker than we expected even a decade ago,” Anna Hogg, an expert in Earth observation of the polar regions at the University of Leeds in England who did not participate in the study, tells BBC News.

If larger glaciers than Hektoria, like the Thwaites Glacier—roughly the size of Florida—underwent this kind of shrinkage, it would have “significant implications” for sea-level rise, Ochwat tells ABC News.

Jeremy Bassis, a glaciologist at the University of Michigan who was not involved in the study, tells Science that this research is “telling us that those worst-case scenarios are maybe not as implausible as some people might have thought.”

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