by Massachusetts Institute of Technology, October 21, 2019 in ScicnceDaily

Researchers report 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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A realistic picture

The results suggest that the Earth’s tallest ice cliffs are unlikely to collapse catastrophically and trigger a runaway ice sheet retreat. That’s because the fastest rate at which ice shelves are disappearing, at least as documented in the modern record, is on the order of weeks, not hours, as scientists observed in 2002, when they captured satellite imagery of the collapse of the Larsen B ice shelf — a chunk of ice as large as Rhode Island that broke away from Antarctica, shattering into thousands of icebergs over the span of two weeks.

“When Larsen B collapsed, that was quite an extreme event that occurred over two weeks, and that is a tiny ice shelf compared to the ones that we would be particularly worried about,” Clerc says. “So our work shows that cliff failure is probably not the mechanism by which we would get a lot of sea level rise in the near future.”