Antarctic Ice Sheet Melting to Lift Sea Level Higher Than Thought, Study Says

April 30, 2021
Antarctic Ice Sheet Melting to Lift Sea Level Higher Than Thought, Study Says

New calculations show the rise due to warming would be 30% above forecasts

By JUAN SILIEZAR, The Harvard Gazette

Global sea-level rise associated with the possible collapse of the West Antarctic Ice Sheet has been significantly underestimated in previous studies, meaning the sea level in a warming world will be greater than anticipated, according to a new study from Harvard researchers.

The report, published in Science Advances, features new calculations for what researchers refer to as a water-expulsion mechanism. This occurs when the solid bedrock the West Antarctic Ice Sheet sits on rebounds upward as the ice melts and the total weight of the ice sheet decreases. The bedrock sits below sea level, so when it lifts it pushes water from the surrounding area into the ocean, adding to global sea-level rise.

The new predictions show that in the case of a total collapse of the ice sheet, global sea-level rise estimates would be amplified by an additional meter, about 3 feet, within the next 1,000 years.

“The magnitude of the effect shocked us,” said Linda Pan, a Ph.D. student in Earth and planetary science in GSAS who co-led the study with fellow graduate student Evelyn Powell. “Previous studies that had considered the mechanism dismissed it as inconsequential.”

“If the West Antarctic Ice Sheet collapsed, the most widely cited estimate of the resulting global mean sea-level rise that would result is 3.2 meters,” said Powell. “What we’ve shown is that the water-expulsion mechanism will add an additional meter, or 30 percent, to the total.”

This is not a story about impact that will be felt in hundreds of years. One of the simulations Pan and Powell performed indicated that by the end of this century, global sea-level rise caused by melting of the West Antarctic Ice Sheet would increase 20 percent by the water expulsion mechanism.

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