Ancient underground streams of heated rock, called a mantle plume, might be an explanation for the instability of Antarctica’s western ice sheet, according to a new NASA study. Scientists have been debating whether or not mantle plume heat contributes to western Antarctica’s instability. Some recent studies provided evidence this might be the case, but even this study’s authors were skeptical.
“I thought it was crazy,” Hélène Seroussi, the study’s co-author and scientist at NASA’s Jet Propulsion Laboratory, said in a release.
“I didn’t see how we could have that amount of heat and still have ice on top of it,” Seroussi said in a statement.
NASA says Seroussi’s study provides more evidence of geothermal activity underneath a portion of the world’s largest ice sheet.
Scientists tend to worry more about future global warming’s effect on Antarctic ice sheet. NASA glaciologist Eric Rignot said western ice sheet collapse is “unstoppable” and could dramatically raise sea levels.
However, Antarctica has gone through periods of instability in the past. Seroussi’s study provides important context for the western ice sheet’s instability, and how mantle plumes may play a role.
Seroussi and co-author Erik Ivins used enhanced numerical modeling to see if a mantle plume could really be creating rivers of melted water under Marie Byrd Land in western Antarctica. They compared their model to real-world observations of changes in the ice sheet.
Scientists think mantle plumes are thin streams of heated rock that makes its way upward, melting ice and creating rivers and lakes of meltwater under Antarctica’s western ice sheet. Mantle plumes could have contributed to ice sheet instability about 11,000 years ago.
Seroussi’s study showed a mantle plume pushes 150 milliwatts per square meter of heat up towards the ice sheet. That’s about two to three times the heat flux of regions of the world without volcanic activity.
A 2014 University of Texas study found western Antarctica was a literal hotbed for geothermal heat. Researchers concluded that “large areas at the base of Thwaites Glacier are actively melting in response to geothermal flux consistent with rift-associated magma migration and volcanism.”
The following year, another team of U.S. scientists found there’s a huge amount of geothermal heat under western antarctica. “The high geothermal heat flux may help to explain why ice streams and subglacial lakes are so abundant and dynamic in this region,” the study found.
Earlier this year, Scottish researchers found 91 previously unidentified volcanoes under the Antarctic ice sheet, including one that’s some 13,000 feet tall.
If one of these volcanoes were to erupt it could further destabilise west Antarctica’s ice sheets,” Robert Bingham,a study co-author, told The Guardian. “Anything that causes the melting of ice – which an eruption certainly would – is likely to speed up the flow of ice into the sea.
“The big question is: how active are these volcanoes? That is something we need to determine as quickly as possible,” Bingham said.