Geothermal Heating Discovered Beneath Antarctic Ice Sheet May Cause Instability

Scientists have discovered surprisingly high geothermal heating beneath the Antarctic ice sheet. They've uncovered a large amount of heat flowing toward the base of the ice sheet from geothermal sources deep within Earth.

"The ice sheet developed and evolved with the geothermal heat flux coming from below-it's part of the system," said Andrew Fisher, one of the researchers, in a news release. "But this could help explain why the ice sheet is so unstable. When you add the effects of global warming, things can start to change quickly."

The new study was actually part of a large Antarctic drilling project. The scientists measured temperatures in sediments below Subglacial Lake Whillans, which lies beneath a half a mile of ice. After boring through the ice sheet with a special hot-water drill, the researchers lowered the probe through the borehole until it buried itself in the sediments below the subglacial lake. The probe then measured temperatures at different depths in the sediments, revealing a rate of change in temperature with depth about five times higher than that typically found on continents.

The geothermal heating actually contributes to the melting of basal ice, which supplies water to a network of subglacial lakes and wetlands that scientists have discovered underlies a large region of the ice sheet. In previous research, in fact, scientists have uncovered a diverse microbial community in the same lake.

The newly discovered geothermal heat flux is an important value for the computer models that scientists are using to understand why and how quickly the West Antarctic ice sheet is shrinking.

"It is important that we get this number right if we are going to make accurate predictions of how the West Antarctic ice sheet will behave in the future, how much is melting, how quickly ice stream flow, and what the impact might be on sea level rise," said Slawek Tulaczyk, one of the researchers. "I waited for many years to see a directly measured value of geothermal flux from beneath this ice sheet."

The findings are published in the journal Science Advances.

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