The global sea level rise associated with the possible collapse of the West Antarctic ice sheet has been significantly underestimated in previous studies, meaning that sea levels in the warming world will be higher than expected, according to a new study by Harvard researchers.
The report published in Scientific progress, includes new calculations for what researchers call a water discharge mechanism. This occurs when the solid base of the Western Antarctic ice sheet sits upward as the ice melts and the total weight of the ice sheet decreases. The base is below sea level, so when it rises, it pushes water out of the surrounding ocean into the ocean, adding to global sea level rise.
The new forecasts show that in the event of a complete collapse of the ice sheet, forecasts of global sea level rise will be increased by an additional meter within 1
“The scale of the effect shocked us,” said Linda Pan, MD. in Earth and Planetary Science at GSAS, who is leading the study with fellow student Evelyn Powell. “Previous studies that have looked at the mechanism have dismissed it as insignificant.”
“If the Western Antarctic ice sheet collapses, the most commonly cited estimate of the resulting global average sea level rise that would lead to this is 3.2 meters,” Powell said. “What we’ve shown is that the water disposal mechanism will add an extra meter, or 30 percent, to the total.”
But this is not just a story about the impact that will be felt in hundreds of years. One of the simulations conducted by Pan and Powell states that by the end of this century, rising sea levels caused by the melting of the ice sheet of West Antarctica will increase by 20% of the water discharge mechanism.
“Any published forecast of sea level rise due to the melting of the Antarctic ice sheet, which is based on climate modeling, whether the forecast extends to the end of this century or longer in the future, will have to be revised upwards, because of their work, “said Jerry X. Mitrovica, Frank B. Baird, a professor of science in the Department of Earth and Planetary Sciences and senior author of the article.
Pan and Powell, both researchers at Mitrovica’s lab, began the study while working on another sea level change project, but switched to that when they noticed more water discharge from the western Antarctic ice sheet than expected.
Researchers want to study how the ejection mechanism has affected sea level change, given the low viscosity or easily flowing material of the Earth’s mantle beneath West Antarctica. When they included this low viscosity in their calculations, they realized that water displacement had occurred much faster than previous models had predicted.
“No matter what scenario we used to collapse the Western Antarctic ice sheet, we always found that this extra meter of global sea level rise had happened,” Pan said.
The researchers hope that their calculations show that in order to accurately assess sea level rise associated with melting ice sheets, scientists must include both the effect of water displacement and the low viscosity of the mantle under Antarctica.
“Sea level rise doesn’t stop when the ice stops melting,” Pan said. “The damage we are doing to our shores will continue for centuries.”
The effect of Antarctica on sea level rise in the following centuries
“Rapid rebound after smooth intensifies global sea level rise after West Antarctic ice sheet collapses” Scientific progress (2021). DOI: 10.1126 / sciadv.abf7787
Provided by Harvard University
Quote: Antarctic ice cover is melting to raise sea levels higher than expected, according to a study (2021, April 30) received on May 1, 2021 from https://phys.org/news/2021- 04-antarctic-ice-sheet-sea-higher -thought.html
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