Until now, it was believed that such shifts in ice flow occurred over centuries or even millennia. However, high-resolution satellite imagery reveals that one glacier has been steadily redirecting ice from a slower-moving neighbor in the Pope, Smith, and Kohler (PSK) region of West Antarctica, profoundly altering the region's ice dynamics.
A study led by the University of Leeds found that seven ice streams in this area have significantly accelerated, with one stream nearly doubling its speed by 87% at the boundary where it meets the ocean between 2005 and 2022. Three other streams showed speed increases between 60% and 84% during the same period, with six of the streams averaging over 700 meters per year in 2022 - a rapid pace for Antarctic ice.
The research team noted that grounding lines, the critical points where glaciers transition from resting on the bedrock to floating, have been shifting. These lines serve as key indicators of glacial instability, reflecting how ice sheets respond to changing oceanic and atmospheric conditions.
Remarkably, while most glaciers in this region have accelerated, one ice stream, Kohler West, has slowed by 10% over the same period. In stark contrast, its neighbor, Kohler East, along with Smith West Glacier, experienced the fastest acceleration, moving about 560 meters per year faster in 2022 than in 2005.
Lead author Dr. Heather L. Selley, a PhD researcher in the School of Earth and Environment at the University of Leeds, explained: "We think that the observed slowdown on Kohler West Glacier is due to the redirection of ice flow towards its neighbour - Kohler East. This is due to the large change in Kohler West's surface slope, likely caused by the vastly different thinning rates on its neighboring glaciers."
Dr. Selley continued: "Because Kohler East's ice stream is flowing and thinning faster as it travels, it absorbs, or 'steals' ice from Kohler West. This is effectively an act of 'ice piracy', where ice flow is redirected from one glacier to another, and the accelerating glacier is essentially 'thieving' ice from its slowing neighbour."
The study utilized data from multiple satellite missions, including the European Space Agency's (ESA) CryoSat, along with contributions from the British Antarctic Survey (BAS) and the UK Centre for Polar Observation and Modelling (CPOM), based at Northumbria University.
Professor Anna Hogg, a study co-author and Professor of Earth Observation at Leeds, noted that the changes in flow direction have significantly altered the mass flux into nearby ice shelves, particularly the Dotson and Crosson shelves, potentially influencing their long-term stability.
Research Report:Speed-up, slowdown, and redirection of ice flow on neighbouring ice streams in the Pope, Smith and Kohler region of West Antarctica
Related Links
University of Leeds
Beyond the Ice Age
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