Antarctica at risk: ice sheets vulnerable to pulses of rapid retreat

Eurasian Ice Sheet retreated rapidly during the last deglaciation, highlighting the vulnerability of flat-bedded ice sheets and a potential for rapid retreat due to climate change.
Kavita Verma
Thwaites Glacier pillars
Thwaites Glacier pillars


A warning from the past about ice sheet retreat

According to a recent study, ice sheets can recede up to 600 meters a day during times of climate warming. This rate is 20 times faster than the previous highest recorded retreat. An international team of researchers, led by Dr. Christine Batchelor of Newcastle University, used high-resolution seafloor images to examine the retreat of an ice sheet that extended from Norway about 20,000 years ago. Their findings highlight the rapid and potentially catastrophic effects of climate warming on ice sheets.

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    Corrugation ridges on the seafloor of mid-Norway

    The research team, which included scientists from the Geological Survey of Norway and from universities such as Cambridge and Loughborough in the UK, utilized seafloor mapping techniques to identify more than 7,600 small-scale features called 'corrugation ridges.' These ridges, which are spaced between 25 and 300 meters apart and stand at less than 2.5 meters high, were extensively studied as part of the research effort. 

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    Highly dynamic SCAR Inlet Ice Shelf, Antarctic Peninsula

    As per the research findings, these small-scale landforms called 'corrugation ridges' were likely formed due to the movement of the retreating margin of the ice sheet. As the ice sheet’s retreating edge moved up and down with the tides, the seafloor sediments were pushed into a ridge. Since two tidal cycles occur every day, two ridges were produced daily, allowing the researchers to calculate the speed at which the ice sheet receded. 

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    Understanding climate change and its effects on ice sheets

    The team's findings, reported in the journal Nature, indicate that the ice sheet underwent periodic rapid retreat, at speeds ranging from 50 to 600 meters per day. This retreat rate is considerably faster than any recorded satellite observations or similar landforms in Antarctic ice sheets. Understanding how ice sheets reacted during past periods of climate change or warming is crucial for developing accurate computer models that can predict future ice sheets and sea-level changes.

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    The mechanisms of ice sheet collapse

    According to the recent study, it appears that episodes of rapid ice-sheet retreat, which may last for only brief periods (ranging from days to months), can be triggered by specific mechanisms. The seafloor landforms identified in the research provide insight into how such rapid retreats occur. The team led by Dr. Batchelor observed that the ice sheet had retreated most quickly across the flat areas of its bed.

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    West Antarctica's Thwaites Glacier crevassing from flat areas of its bed

    One of the paper's co-authors, Dr. Frazer Christie of the Scott Polar Research Institute, explained that an ice margin can rapidly "unground" from the seafloor and retreat "near-instantly" when it becomes buoyant. This type of retreat occurs primarily on flat beds, requiring minimal melting to reduce the thickness of the ice to the point where it becomes buoyant. 

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    Fractured frontal margin of Thwaites and Crosson ice shelves

    The research team concluded that similar rapid retreats could occur soon in various Antarctic ice sheets, including the Thwaites Glacier, part of the West Antarctica ice sheet. The Thwaites Glacier has gained significant attention globally due to its potential for rapid and unstable retreat owing to climate change. The study's authors propose that the Thwaites Glacier may experience an episode of rapid retreat since it has recently receded near a flat portion of its bed.