Greenland Ice Sheet Melting Increased Due To Ancient Geothermal Hot Spots

Along with climate change, the earth's internal heat may also be raising rapid ice flow and subglacial melting of the Greenland Ice Sheet, discover scientists. Hence, ice sheets may be melting from the "inside out" too.

An international team of researchers found that half the ice-covered area in north-central Greenland actually is laid on a thawed sheet. Moreover, meltwater from the ice sheet flows into the ocean through a complex underlying hydrological network.

"The strength of this paper is that many different lines of reasoning about data lead to the same conclusion," said Jesse Johnson, a University of Montana researcher and ice sheet modeler. "I was able to demonstrate that the ice velocities observed by satellite are nearly impossible to explain without the geothermal anomaly discovered here. Glaciologists have long suspected the anomaly exists, but this work quantifies its location and degree and explains why it is there."

These ice sheets originated between 35 million and 85 million years ago, even as tectonic processes moved Greenland over abnormally hot mantle material that has now led to volcanic eruptions in Iceland.

Hence, scientists located extraordinary high temperatures in the west to the east zone of northern Greenland. Even as this area creates intense heat, it makes Greenland's ice melt from below and flow in great speed.

"This ancient and sustained source of heat has created a region having warmer, softer ice and abundant subglacial meltwater, lubricating the base of the ice and making it flow rapidly," Johnson added.

Hence, the widespread melting that was originally recorded from radar observations and ice core drilling is explained. It also indicates increased sliding at the base of the ice, leading to rapid ice flow over 750 kilometers from the peak of the Greenland ice sheet to the North Atlantic Ocean.

"The geothermal anomaly which resulted from the Icelandic mantle-plume tens of millions of years ago is an important motor for today's hydrology under the ice sheet and for the high flow-rate of the ice," added Irina Rogozhina, co-researcher from the GFZ German Research Centre for Geosciences. "This, in turn, broadly influences the dynamic behavior of ice masses and must be included in studies of the future response to climate change."

The study indicates the reasons for Greenland's ice melt, and also shows the link between the earth's deep geothermal record as well as ice sheet dynamics.

Their study was recently published in the journal Nature Geoscience.