Radioactive Rocks Under Antarctica Make an Area of Ice the Size of Rhode Island Disappear

Scientists discovered that an area of ice bigger than Rhode Island was missing from the South Pole—and believe an unusual, previously unidentified hot spot powered by radioactive rocks and heated water is to blame.

Researchers with the British Antarctic Survey (BAS) were studying the the ice streams that started at the interior of the East Antarctic Ice Sheet and drained out toward the coast. They were looking at the geothermal activity that causes changes to the ice—recent models indicated small, localized changes could have a big impact on the flow of ice.

Previously, scientists had predicted that there would be "geothermal anomalies" beneath the ice—but direct evidence of this has been lacking.

The team used radar to peer through 1.8 miles of ice in an area close to the South Pole. From this they were able to measure how thick the ice was and reveal huge subglacial basins beneath. One area in particular was particularly unusual. They found an area of ice bigger than Rhode Island appeared to be missing.

Publishing their results in the journal Scientific Reports, the researchers reported an area where an unusual amount of geothermal heat was being generated. This heat source appears to be melting the ice above—and is causing the layers of the ice sheet above to sag down.

It appears the geothermal heat was the result of "radiogenic granitoids"—or hot, radioactive rocks—and hot water bubbling up from deep underground. After the ice melted, the water drained away and filled up subglacial lakes farther downstream.

antarctica melting
Graphic shows how scientists used aerial radar to map the ice sheet and bed. Tom Jordan

"The process of melting we observe has probably been going on for thousands or maybe even millions of years and isn't directly contributing to ice sheet change," Tom Jordan from the BAS and lead author of the study, said in a statement. "However, in the future the extra water at the ice sheet bed may make this region more sensitive to external factors such as climate change".

"This was a really exciting project, exploring one of the last totally unsurveyed regions on our planet. Our results were quite unexpected, as many people thought this region of Antarctica was made of ancient and cold rocks, which had little impact on the ice sheet above. We show that even in the ancient continental interior, the underlying geology can have a significant impact on the ice."

The findings, the researchers said, indicated there could be many more localized sources of geothermal heat that we do not yet know about. "Assessing their influence on subglacial hydrology and ice sheet dynamics requires new detailed geophysical observations," they said.

The findings followed research last year that showed there was a huge mantle plume beneath West Antarctica that appeared to be melting the ice from beneath. Published in the Journal of Geophysical Research: Solid Earth, the study found the mantle plume produced almost as much heat as Yellowstone supervolcano and was responsible for creating huge lakes and rivers beneath the ice.