Scientists have discovered a glacier in Antarctica committing "ice piracy" – stealing ice from its neighbour in a phenomenon previously thought to take hundreds or thousands of years.
Research led by the University of Leeds has revealed that this dramatic glacial theft has occurred over less than 18 years, challenging scientific understanding of Antarctica's ice dynamics and potential sea level rise contributions.
Dr Pierre Dutrieux, climate researcher at the British Antarctic Survey (BAS) and study co-author, explained the significance of the findings:
"This study provides an interesting demonstration of ice piracy, where flow into one glacier gradually switches to flow into another glacier, as the ocean melts the grounding zone and re-configures ice flow."
Using high-resolution satellite data, the international research team measured ice speed changes in the fast-changing Pope, Smith and Kohler (PSK) region of West Antarctica between 2005 and 2022. They found that seven ice streams had significantly accelerated, with one almost doubling in speed (87%) at the boundary where ice meets ocean. Three others increased speed by 60-84% during this period.
The most striking observation was the contrasting behaviour between neighbouring glaciers. While Kohler East and Smith West Glaciers flowed approximately 560 metres per year faster in 2022 compared to 2005, Kohler West actually slowed by 10%.
Dr Heather Selley, lead author who conducted the research as a PhD researcher at the University of Leeds, said:
"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 neighbouring glaciers.
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 team calculated ice velocity using tracking techniques that measure the displacement of visible surface features such as crevasses. They also incorporated ice-thinning data from the European Space Agency's CryoSat mission.
Professor Anna Hogg from the University of Leeds added:
"The changes in flow direction have substantially altered the ice mass flux into Dotson and Crosson Ice Shelves.
This suggests 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 research represents a significant collaboration between Leeds, BAS, and the UK Centre for Polar Observation and Modelling, using satellite data from multiple international space agencies.
These observations are crucial for understanding Antarctica's future evolution and its contribution to global sea level rise. Over 410 million people could be at risk from rising sea levels by 2100 as a result of climate change, with global levels already having risen by more than 10 cm over the last decade.
The research, published in the journal The Cryosphere, was funded by UKRI Natural Environment Research Council, the European Space Agency, and NASA Headquarters.
'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 is published in The Cryosphere today.
