At 600 meters a day, the Eurasian ice sheet recedes rapidly

British scientists have found that during the last glacier retreat, the Eurasian ice sheet retreated up to 600 meters a day on the Norwegian continental shelf. These findings suggest that the rate of ice sheet retreat in this area may be much higher than previously estimated, highlighting the vulnerability of horizontal regions of the ice sheet to rapid regression pulses. The study was recently published in Nature.

Ice sheets in many coastal areas of Greenland and Antarctica have retreated over the past few decades, causing global sea levels to rise by about 0.7 millimetres per year since the nineties. Using shipboard imagery, the rate of retreat of the ice sheet grounding line (where glaciers and ice shelves begin to float) can be quantified using the intervals at which regular ridges form (called wavy ridges) in de-icling areas of the seafloor. However, the few existing measured wavy ridges are confined to smaller areas of the seafloor, limiting the understanding of future grounding line receding and sea level rise rates.

To quantify the rate at which the ice sheet grounding line receded during the last de-glacing period, Christine Batchelor of Newcastle University and colleagues measured more than 7,600 wavy ridge intervals over 30,000 square kilometers of seafloor de-icing on the central Norwegian shelf. They found evidence of rapid grounding line receding, passing through the nearly flat ice sheet bottom terrain at a speed of 55~610 meters per day during the last de-icing period. These values are an order of magnitude higher than previously reported grounding line fading data from satellite measurements or extrapolation from the marine geological record. The highest retreat rates occur in the flattest pre-seafloor regions, indicating near-instantaneous ice sheet de-egeneration and retreat near the point where the ice sheet grounding line is completely afloat.

Batchelor believes that under today’s climate change, pulses of rapid ground line regression could occur in low-slope Antarctic ice sheet terrain. (Source: China Science News, Jinnan)

“Iceberg factory” in West Antarctica. Sentinel 1 image synthesis depicts the highly fractured and fast-flowing frontal edge of the Thwaites and Crossonice continental shelves. Image from the author

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