Earth's Heat Possible Culprit in Greenland's Melting

Researchers at Ohio State University have found what they think could a contributing factor in the melting of Greenland's ice. Thin places in the Earth's crust could be allowing magma to heat up rock underneath the ice, and at least one hotspot has been found below a recently discovered ice stream.

Ralph von Frese, the project's leader and professor of earth sciences at the univeristy, explained how the thickness of the crust impacted temperatures. Under the crust, the earth's mantle, made of partially molten rock, continuously warms the crust and the Earth's surface. Although the earth's crust is usually tens of miles thick, at even just a few miles deep the crust can reach hundreds of degrees.

"Where the crust is thicker, things are cooler, and where it's thinner, things are warmer. And under a big place like Greenland or Antarctica, natural variations in the crust will make some parts of the ice sheet warmer than others," he said.

The Naval Research Laboratory took gravity measurements of the area, and colleagues from the University of Kansas took airborne radar measurements to give an idea of how the crust was changing in mass. Not only the mass of the crust under Greenland was changing, but the topography, too.

Researchers believe that a change in temperatures in the ground beneath the ice, the change in topography, and the already thinning ice is leading to the faster flow of new ice streams into the Atlantic. Crustal heat seems to be a significant contributor according to their preliminary results.

Kees van der Veen, a collaborating scientist from the University of Kansas, said,"Recent observations indicate that the Greenland Ice Sheet is much more active than we ever believed. There have been rapid changes in outlet glaciers, for example. Such behavior is critically linked to conditions at the ice bed. Geothermal heat is an important factor, but until now, our models have not included spatial variations in heat, such as this hotspot."