Researchers sampling the water beneath the Young Sound fjord, still covered in ice in the springtime. Image: Søren Rysgaard

Greenland is shedding ice like a popsicle on defrost, and climate change is to blame. But some of Greenland’s fast-flowing glaciers may also be feeling the burn of different heat source—one that hails from Earth’s deep interior.

A study out today in Nature Scientific Reports offers evidence of a significant geothermal heat source warming the bottom of a fjord in northeastern Greenland. This heat source, which roughly corresponds to a 2 megawatt (MW) wind turbine powering a heater beneath the fjord (or enough power to light up roughly 1,600 American homes), lubricates the base of overlying glaciers, potentially accelerating their journey toward the sea.

It’s among the first direct measurements of geothermal heat flux in Greenland, but the findings don’t really come as a surprise: Geothermal hot springs have been discovered all over Earth’s largest island. Northeast Greenland, in particular, is known to feature “abundant geothermal activity,” as study lead author Soren Rysgaard of Aarhus University put it in a statement.

A glacier near Young Sound, where a geothermal heat source was measured in the new study. Image: Mikael Sejr

As study co-author Jørgen Bendtsen explained to Earther in an email, the study was motivated by unusually high temperature readings observed at the bottom of the Young Sound fjord, a 56-mile-long fjord in northeast Greenland, in 2005. The researchers took temperature measurements in the deepest part of the fjord for the next ten years, and used them to estimate a geothermal heat flux of roughly 100 mW per square meter.

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As the authors note, that’s “much higher” than previously reported values from southern Greenland, but falls in line with some indirect measurements of geothermal heat in central northern Greenland. “Combining our measurements with other sites of reported geothermal activity around Greenland clearly shows that East Greenland is a hotspot,” the authors wrote.

Mathieu Morlighem, an ice sheet modeler at the University of California, Irvine who wasn’t involved with the study, said the new data is important because “we know geothermal heat is very important [in Greenland], and we know very little about it. The uncertainty is close to 100 percent,” he said.

He emphasized, however, that while understanding geothermal heat is important for improving models of Greenland’s glaciers, it doesn’t explain why many coastal glaciers are dwindling rapidly today. That’s due to human carbon emissions messing with the planetary thermostat.

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“There’s a subtext that maybe increased geothermal heat flux could be the reason why this glacier is accelerating,” Morlighem said. “My take is this spot has probably been hot for thousands of years, and the ice stream has adjusted. And the changes we see are more related to climate change.”

Mike MacFerrin, a glaciologist at the University of Colorado who also wasn’t involved, added that the findings are consistent with other work suggesting geothermal heat may be part of the reason the nearby Northeast ice stream—a hundreds-of-miles-long ice flow that drains into several massive coastal glaciers—is moving so fast. He, too, emphasized that the destabilization of those coastal glaciers in recent years is due to climate change.

In other words, if we want to prevent Greenland from melting much further and adding many feet of sea level to our coastlines in decades to come, we’ve got to get carbon in the atmosphere under control.

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Though, if we don’t, at least future humans living on ice-free Greenland will have an abundant source of clean energy?