Ice on the Greenland Ice Sheet doesn’t just melt. The ice actually slides rapidly across its bed toward the ice sheet’s edges.
Ice on the Greenland Ice Sheet doesn’t just melt. The ice actually slides rapidly across its bed toward the ice sheet’s edges. As a result, because ice motion is from sliding as opposed to ice deformation, ice is being moved to the high-melt marginal zones more rapidly than previously thought.
Neil Humphrey, a University of Wyoming professor of geology and geophysics, and Nathan Maier, a UW geology Ph.D. student from Morristown, N.J., headed a recent research group that discovered that you do not need beds with till or mud, which acts as a lubricant, to have high rates of sliding. Rather, they discovered that it is over hard bedrock where ice slides more rapidly. Additionally, the ice slides over the bedrock much more than previous theories predicted of how ice on the Greenland Ice Sheet moves.
“That’s the kicker. The Greenland Ice Sheet is happily sliding over a surface that theory says it shouldn’t be able to rapidly slide over,” Humphrey says. “What’s important is that, because of this, you get a lot of ice to the oceans or low altitudes where it can melt really fast. It’s like a lump of molasses sliding off the continent. It just doesn’t melt. It slides toward the ocean.”
“Our measurements of sliding-dominated flow over a hard bed in a slow-moving region were quite surprising because people don’t typically associate these regions with high sliding,” Maier adds. “Generally, people associate lots of sliding motion with regions that have soft beds (mud) or exceptionally high-sliding velocities, such as ice streams. Yet, in this relatively boring region, we found the highest fraction of sliding measured to date.”
Read more at: University of Wyoming
Neil Humphrey (left), a UW professor of geology and geophysics, and Nathan Maier, a UW geology Ph.D. student, pose on the Greenland Ice Sheet during 2017 field research. The two wrote a paper, titled “Sliding Dominates Slow-Flowing Margin Regions, Greenland Ice Sheet,” that was published July 10 in Science Advances. (Photo Credit: Neil Humphrey Photo)