Greenland is composed of about 80 percent ice, but atmospheric warming is causing it to melt. And, according to research published Wednesday in Nature, it’s melting from the bottom and the top.

The ice sheet in Greenland usually moves under the pressure of its own weight and the forces of gravity at a very slow pace. But with melt water forming trapped sub-glacial lakes and heating the ice from beneath, the glaciers in Greenland may be responding more rapidly to climate change than previously predicted. And faster glacial movement in any place could lead to higher sea levels.

“We’re seeing surface melt water make its way to the base of the ice where it can get trapped and stored at the boundary between the bedrock beneath the ice sheet and the ice itself,” Cornell University Earth and Atmospheric Sciences researcher Michael Willis said. “As the lake beneath the ice fills with surface melt water, the heat released by this trapped melt water can soften surrounding ice, which may eventually cause an increase in ice flow.”

Willis, along with University of Minnesota School of Earth Science’s Polar Geospatial Center’s Bradley Herried and researchers from Ohio State University School of Earth Sciences and Columbia, has been mapping the ice sheet for about three years using data collected from high-resolution satellite images from the University of Minnesota’s Polar Geospatial Center, as well as data from NASA’s operation IceBridge.

Read Monday’s Daily for more information on the research.