Greenland’s arctic ice sheet is in trouble – and it turns out that global warming isn’t the only force at work. A new study in Nature Geoscience by the GFZ German Research Center for Geosciences shows that high heat flow from the planet’s interior into the lithosphere (the area between the Earth’s crust and upper mantle) is accelerating Greenland’s ice melt.
Every year, Greenland loses 227 gigatons of ice, contributing 0.7 millimeters to the overall annual sea rise of 3 milimeters. Until now, climate modeling data has mostly focused on the impact of global warming without considering the effect of heat traveling into the lithosphere. GFZ scientists Alexey Petrunin and Irina Rogozhina addressed both causes of ice loss in an article published in the latest edition of Nature Geoscience.
“We have run the model over a simulated period of three million years, and taken into account measurements from ice cores and independent magnetic and seismic data,” says Petrunin. “Our model calculations are in good agreement with the measurements. Both the thickness of the ice sheet as well as the temperature at its base are depicted very accurately. ”
Their model is so precise that it can determine the temperature between two adjacent drill holes, the thickness of the ice sheet, and the heat flow between sites. They have successfully determined the temperature at the base of the ice sheet, and shed light on the history of glacial cycles and how they relate to global warming.
Greenland’s lithosphere is 2.8 to 1.7 billion years old and is 70 to 80 kilometers thick under Central Greenland. It has yet to be discovered why the sheet is so thin, but it is clear that the disappearance of the ice sheet is due to a combinations of forces both above and below the frozen expanse.
Images via GFZ and Wikicommons user Hannes Grobe.