A 1973 satellite image of the Pine Island Glacier Ice Shelf in Antarctica showing several visible bumps on the ice surface. Credit: University of Edinburgh

The undersea ice anchors that help prevent Antarctica’s land ice from sliding into the ocean are shrinking at more than twice the rate of 50 years ago, research shows.

More than a third of these frozen moorings, known as pinning points, have shrunk in size since the turn of the century, experts say.

Scientists have warned that further deterioration of the pinning points, which hold the floating ice sheets that strengthen Antarctica’s land ice in place, will accelerate the continent’s contribution to sea level rise. There is paper. published I The nature.

The first study

Floating ice sheets cover 75 percent of Antarctica’s coastline and cover an area the size of Greenland.

The findings are part of the first study of changes in the thickness of the Antarctic ice shelf – the extension of land ice that floats on the ocean – stretching back to 1973. Previous observations date back to 1992 only.

Researchers at the University of Edinburgh used From a 50-year archive of the NASA/United States Geographical Survey (USGS) Landsat program to track variations in the appearance of pinning points on the ice surface.

Pinning points are formed when part of a floating ice sheet anchors itself aloft. creating a visible bump on the surface of an otherwise smooth ice shelf.

  • Ice-melt barriers are disappearing at twice the rate since the mid-20th century.

    The ice shelf of Pine Island Glacier in 2001. The pinning points are mostly smooth indicating that the floating ice has lost contact with high points on the sea floor. Credit: University of Edinburgh

  • Ice-melt barriers are disappearing at twice the rate since the mid-20th century.

    The ice shelf of Pine Island Glacier in 2024. The thinning shelf has lost ice along its front and northern margins, and fractured ice is visible on the southern edge. Credit: University of Edinburgh

Ice shelf

Using changes in pinning points as a reliable proxy for changes in ice shelf thickness, the team measured changes in these properties over three time periods: 1973 to 1989, 1990 to 2000, and 2000 to 2022. .

The scientists found that between 1973 and 1989, only 15 percent of pinning points shrank in size, causing small localized pockets of ice shelf thinning.

However, in the 1990s, large-scale acceleration and drift of ice shelves from pinning points began in the West Antarctic Peninsula and Amundsen Sea.

The number of pinning points increased by 25% from 1990 to 2000 and 37% from 2000 to 2022.

“The switch from relatively limited and regionally concentrated ice shelf melting over the past 50 years, to much more widespread melting, is striking. The ongoing concern is how many of these tipping points over the next 50 years. The melting will begin, says Dr. Bertie Miles.

“What we’re seeing around Antarctica is a sustained onslaught of climate warming, which turns the pace of ice melt into global sea level rise,” says Professor Robert Bingham.

More information:
Bertie WJ Miles et al, Progressive unanchoring of Antarctic ice shelves since 1973, The nature (2024). DOI: 10.1038/s41586-024-07049-0

Reference: Melting ice barriers disappearing at twice the rate of 50 years ago, study shows (2024, February 23) February 23, 2024 https://phys.org/news/2024-02-ice- Retrieved from barriers-years.html

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