Glaciers feeding the Dotson and Crosson Ice Shelves in West Antarctica are among the fastest-changing. A new study used satellite data to track shifts in speed and direction across eight ice streams in the Pope, Smith, and Kohler region from 2005 to 2022.
The ESA study found that Kohler East Glacier has been pulling ice from its slower-moving neighbor in a process known as ice piracy.
Kohler, Pope, and Smith Glaciers are thinning and shifting at different rates. As their ice flows into the Amundsen Sea, it impacts sea-level rise, making them key indicators of climate change.
Using high-resolution images from satellites like Sentinel-1, researchers tracked the flow rates of eight ice streams in the Pope-Smith-Kohler region.
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They measured changes in glacier speed by monitoring surface features such as crevasses and rifts, along with ice-thinning data from ESA’s CryoSat mission. Their findings showed that seven ice streams had accelerated, one nearly doubling in speed, while one unexpectedly slowed down.
Curiously, Kohler East is the fastest-moving glacier next to Kohler West, which remains much slower. This highlights the complex dynamics shaping West Antarctica’s ice flow.
Scientists found that Kohler East, the fastest-moving glacier, is now pulling ice from its slower neighbor, Kohler West, as its flow direction shifts.
Since 2005, glaciers in the Pope-Smith-Kohler region have sped up by 51% on average, though rates vary. Four glaciers accelerated by 60-87% over 17 years; in 2022, six streams reached speeds of over 700 meters per year.
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The fastest glaciers—Kohler East and Smith West—each gained an average of 32 meters yearly. Surprisingly, Kohler West slowed down by 10%, highlighting the unpredictable nature of glacial changes.
Scientists found that Kohler West’s slowdown is due to a shift in its flow direction, toward its faster-moving neighbor, Kohler East. This shift is likely caused by the difference in thinning rates between the two glaciers.
As Kohler East thins and moves faster, it pulls ice from Kohler West in an ice piracy process, where one glacier siphons ice from another. This redirection highlights the dynamic nature of glacial movement.
Satellite data reveals that these dramatic shifts occur in less than 18 years, far faster than scientists thought.
Antarctica’s glaciers are accelerating, with some of the highest recorded ice thinning and grounding-line retreat rates. The grounding line—where glaciers transition from land to floating ice shelves—is shifting, increasing instability and speeding up ice flow into the ocean, intensifying sea-level rise.
Prof. Anna Hogg emphasizes that ice flow redirection is becoming a critical factor in modern ice-sheet dynamics. Understanding this process is key to interpreting current glacier changes and forecasting their future evolution.
This discovery reveals new connections between floating ice shelves and grounded ice sheets—interactions that will shape sea-level rise and impact the overall mass of ice sheets throughout the 21st century, refining climate predictions for polar regions.
Journal Reference:
- Heather Selley, Anna Hogg, Benjamin Davison et al. Speed up, slow down, and redirect ice flow on neighboring ice streams in the Pope, Smith, and Kohler regions of West Antarctica. The Cryosphere. DOI: 10.5194/tc-19-1725-2025
