First map of thawing under Greenland iceGreenland’s ice sheet insulates its own bottom layer, which is warmed from below by Earth’s heat. Which bottom layers are now thawed, and which are still frozen? NASA said on August 3, 2016 that its researchers have helped produce a first-of-its-kind map showing where the Greenland ice sheet is likely thawed at its base. The thawing comes in part from Earth’s heat and affects how fast the ice flows to the sea. The Journal of Geophysical Research – Earth Surface published the new study last month. It comes on the heels of an unrelated study showing ice melt in Greenland could release Cold War-era toxic waste. How can we know what’s happening under Greenland’s ice? The sparse direct observations available come from through fewer than two dozen boreholes that have reached the bottom. The new study synthesizes several methods to infer whether the bottom of the ice is melted or not. For the study, the researchers: – Examined results from eight recent
computer models of the ice sheet, which predict bottom temperatures. Joe MacGregor, lead author of the study and a glaciologist at NASA’s Goddard Space Flight Center, explained:
NASA pointed out that Greenland’s ice sheet insulates the bedrock below from the cold temperatures at the surface. That means the bottom of the ice is often tens of degrees warmer than at the top, because the ice bottom is slowly warmed by heat coming from the Earth’s depths. NASA added:
Read more about this map from NASA Ice melt could release Cold War-era waste Bottom line: Researchers used a combination of methods to create the first-ever map of thawing at the bottom of Greenland’s ice sheet. The map shows that, predictably, there’s more solid ice toward the center of the ice sheet. http://earthsky.org/earth/first-map-of-thawing-under-greenland-ice |