Sea-Level Rise from Antarctic Ice Shelves Might Be Overestimated, Study Finds

The scientists do warn that there are plenty of other causes of rapid sea-level rise.
Chris Young

MIT researchers have found that predictions about sea-level rise caused by collapsing Antarctic ice shelves may have been greatly overestimated.

It was previously thought that the shelves would break apart, leading to 6 feet of sea-level rise by the end of the century.

The researchers do give the caveat that this doesn't discredit any other sea-level rise predictions, plenty of which, they say, are valid.


Overestimated predictions

Up until recently, scientists thought that large ice cliffs taller than 90 meters (roughly the size of the Statue of Liberty) would rapidly collapse under their own weight.

This, it was thought, would contribute to a huge sea-level rise of over 6 feet by the end of the century — enough to completely flood large coastal cities. Now, MIT researchers have found that this prediction may well be overestimated.

In a paper published in Geophysical Research Letters, the researchers say that there is a big problem with these estimations. For a 90-meter ice cliff to completely collapse, the ice shelves supporting the cliff would have to break apart extremely quickly. The rate of ice loss necessary has never been observed since records began.

“Ice shelves are about a kilometer thick, and some are the size of Texas,” MIT graduate student Fiona Clerc said in a press release.

“To get into catastrophic failures of really tall ice cliffs, you would have to remove these ice shelves within hours, which seems unlikely no matter what the climate-change scenario.”

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Sea-Level Rise from Antarctic Ice Shelves Might Be Overestimated, Study Finds
Crack in Larsen C Ice Shelf, Antarctica. Source: NASA/USGS Landsat

Computer simulations

A more realistic prediction, the researchers say, would be that the ice shelves melt over a matter of days and weeks. This means the cliffs would not collapse under their own weight.

“The current worst-case scenario of sea-level rise from Antarctica is based on the idea that cliffs higher than 90 meters would fail catastrophically,” said Brent Minchew, an assistant professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences.

“We’re saying that scenario, based on cliff failure, is probably not going to play out. That’s something of a silver lining. That said, we have to be careful about breathing a sigh of relief. There are plenty of other ways to get rapid sea-level rise.”

In order to test their theory, the MIT scientists ran computer models that simulated the way the ice would react to different weights and pressures. The team's research is supported, in part, by the National Science Foundation.