The Getz Ice Shelf in West Antarctica photographed from a NASA research airplane by Jeremy Harbeck, a sea ice scientist at NASA Goddard. The image shows ice in the process of calving from the front of the shelf, soon to become an iceberg. Credit: NASA/Jeremy Harbeck

Sea-Level Rise From Antarctic Ice Cliffs May Be Overestimated Because of Faulty Assumptions

Study finds even the tallest ice cliffs should support their own weight rather than collapsing catastrophically.

Antarctica’s ice sheet spans close to twice the area of the contiguous United States, and its land boundary is buttressed by massive, floating ice shelves extending hundreds of miles out over the frigid waters of the Southern Ocean. When these ice shelves collapse into the ocean, they expose towering cliffs of ice along Antarctica’s edge.

Scientists have assumed that ice cliffs taller than 90 meters (about the height of the Statue of Liberty) would rapidly collapse under their own weight, contributing to more than 6 feet of sea-level rise by the end of the century — enough to completely flood Boston and other coastal cities. But now MIT researchers have found that this particular prediction may be overestimated.

In a paper published today in Geophysical Research Letters, the team reports that in order for a 90-meter ice cliff to collapse entirely, the ice shelves supporting the cliff would have to break apart extremely quickly, within a matter of hours — a rate of ice loss that has not been observed in the modern record.

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