Kohler East is one of the fastest-changing glaciers in West Antarctica. Glaciers in this region have the highest recorded rates of thinning and grounding-line retreat in Antarctica. The grounding line is the point at which glaciers on land transition to ice shelves and start to float. If the grounding line retreats, this can cause instability and even faster flow of the ice sheet towards the ocean. Credit: Contains modified Copernicus Sentinel data (2022), processed by ESA
In a dramatic twist, scientists have discovered that one fast-moving glacier in West Antarctica is “stealing” ice from its slower neighbor—a process dubbed “ice piracy.”
This was once thought to take millennia, but satellite data now reveals it can unfold in under two decades. The finding rewrites our understanding of glacial dynamics and raises new concerns for sea-level rise, as the behavior of glaciers appears far more fluid and responsive than previously believed.
Discovery of Fast-Paced Ice Piracy
Thanks to detailed satellite observations from Europe’s Copernicus Sentinel-1 mission, scientists have made a striking discovery in Antarctica. A fast-moving glacier is siphoning ice from a neighboring glacier at a speed never seen before. Until now, experts believed this kind of “ice piracy” unfolded over hundreds or even thousands of years. But the latest findings show it can happen in less than two decades.
Published on May 8 in The Cryosphere, the new study reveals that the Kohler East Glacier in West Antarctica has been pulling ice from a slower-flowing neighbor, changing the way scientists understand how glaciers behave.
West Antarctica’s Fastest-Changing Glaciers
Kohler Glacier, along with nearby Pope and Smith Glaciers, are some of the fastest-changing ice flows in West Antarctica. These glaciers lie just inland from the Dotson and Crosson Ice Shelves, major floating platforms of ice that sit on the Amundsen Sea.
Ice from these fast-moving glaciers eventually flows into the sea, and how quickly that happens plays a direct role in global sea-level rise. As the glaciers move and thin at different rates, the balance between them can shift dramatically, as this new case of ice theft shows.
Satellite Data Reveals Speed Surge
A group of scientists, led by the University of Leeds in the UK, examined high-resolution images from satellites such as Sentinel-1 along with other satellite data spanning 2005 to 2022 to understand the rates of flow from eight ice streams in the Pope-Smith-Kohler region.
They calculated ice velocity using a tracking technique that measures the displacement of visible features, such as crevasses or rifts, on or near the ice surface. Data on ice-thinning rates from ESA’s CryoSat mission were also used in the study.
In doing so, they found that seven of the streams had sped up, one almost doubling its speed, but, in stark contrast, one had actually slowed down.
It turns out that the fastest-flowing glacier, Kohler East, is right next to a slower-flowing glacier, Kohler West.
Ice Piracy in Action
However, the difference in speed of ice flow isn’t the only intriguing aspect of this vulnerable region. The research team also discovered a significant shift in flow direction, which is resulting in the faster Kohler East stream rapidly drawing ice from its slower neighbor, Kohler West.
The researchers found that, on average, the glaciers in the Pope-Smith-Kohler region have sped up by 51% since 2005. However, hidden within this average are some big differences. Four glaciers sped up by between 60% and 87% over the 17 years, and, remarkably, six of the streams reached average speeds of over 700 m per year in 2022 alone.
The fastest were Kohler East and Smith West Glacier, where ice speeds increased by an average of 32 m a year over the 17-year study period.
Kohler West’s Unexpected Slowdown
Given the impacts climate change is having, this doesn’t really come as a surprise. However, what is surprising is the fact that the speed of the Kohler West glacier actually slowed by 10% over the study period.
Lead author Dr. Heather Selley, from the University of Leeds, explained, “We think that this slowdown is because Kohler West also seems to have changed direction and flowed towards its neighbor, Kohler East.
“This change in direction is likely caused by the vastly different thinning rates on the neighboring glaciers.
“Because Kohler East’s ice stream is flowing and thinning faster as it travels, it absorbs, or ‘steals’ ice from the slower-moving Kohler West.
“This is effectively an act of ‘ice piracy’, where ice flow is redirected from one glacier into another, and the accelerating glacier is essentially thieving ice from its slowing neighbor.
A Short Timescale Surprise
“Astonishingly, thanks to satellite data, we can see that this is happening in less than 18 years, whereas we’ve always thought it was this extremely long, slow process.”
These results show that there is a substantial speed-up in this region of Antarctica, which has the highest recorded rates of thinning and grounding-line retreat.
The grounding line is the point at which glaciers on land transition to ice shelves and start to float. If the grounding line retreats, this can cause instability and even faster flow of the ice sheet towards the ocean.
Rethinking Ice-Sheet Dynamics
Prof. Anna Hogg, also from the University of Leeds, added, “Our results suggest that ice flow redirection is an important new process in contemporary ice-sheet dynamics, which is required to understand present-day structural change in glaciers and the future evolution of these systems.
“The data reveal previously unobserved interactions between floating ice shelves and grounded ice sheets, which will affect future sea-level rise, and may influence changes in the mass of ice sheets and ice shelves during the 21st century.”
The Power of Satellite Monitoring
Dr. Martin Wearing, ESA Polar Science Cluster Coordinator, said, “This new study highlights the unique ability of satellites to provide both the temporal and spatial coverage required to assess change in the polar regions.
“Using data from Copernicus Sentinel-1, as well as data on ice thinning from ESA’s CryoSat mission, the team has revealed the complex evolution of ice flow in part of West Antarctica over the past few decades.
“Understanding these changing dynamics and what drives them is crucial for improved projections of future ice-sheet change and contributions to sea-level rise.”
Reference: “Speed-up, slowdown, and redirection of ice flow on neighbouring ice streams in the Pope, Smith, and Kohler region of West Antarctica” by Heather L. Selley, Anna E. Hogg, Benjamin J. Davison, Pierre Dutrieux and Thomas Slater, 8 May 2025, The Cryosphere.
DOI: 10.5194/tc-19-1725-2025
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4 Comments
“Given the impacts climate change is having, this doesn’t really come as a surprise.”
If global warming is driving the changes, why do we not see similar behavior in East Antarctica?
The East Antarctic ice sheet is much bigger and more stable than West Antarctica. The East Antarctic ice sheet will be the last to go, and it will take many thousands of years (most likely tens of thousands) to fully disappear.
Whoa, “ice piracy” sounds like a sci-fi movie — but it’s real?! 87% speed-up is wild. Nature’s not messing around… or maybe we are.
I would suggest seismic and geothermal ground temperatures are a must to be observed , I am not a scientist but the melting difference between the two areas could mean there might be a volcanic disturbance forming under all of Antarctica! Could this be the reason for differences in both poles, something to think about? My thoughts are on a forming volcano or two! Possibilities are what researches are all about and the Earth’s core has many inner flows of lava and molten rock ,in that scenario what are the closest regions of volcanic activities and is it possible to have a flow of lava which will in turn create life such as the new found inhabitants beneath these melting ice shelves? Something else to think about ,such a marvelous planet we are keen to escape by colonizing The moon ,,or Mars , or even the coded planet beyond our system or galaxy