Ice is Sliding Toward Edges Off Greenland Ice Sheet – New Research

Eddie Gonzales Jr. – MessageToEagle.com – Ice on the Greenland Ice Sheet doesn’t just melt but also slides rapidly across its bed toward the ice sheet’s edges, researchers say.

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.

(Greenland Ice Sheet is 5,000 to 10,000 feet thick.)

Meltwater stream flowing into a large moulin in the ablation zone (area below the equilibrium line) of the Greenland ice sheet. (Image courtesy Roger J. Braithwaite, The University of Manchester, UK via GISS)

Meltwater stream flowing into a large moulin in the ablation zone (area below the equilibrium line) of the Greenland ice sheet. source

“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,” Neil Humphrey, a University of Wyoming professor of geology and geophysics, said in a press release.

“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,” adds Nathan Maier, a UW geology Ph.D. student from Morristown, N.J.

“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.”

The researchers installed 212 tilt sensors within a network of boreholes drilled into the ice bed. These sensors allow observations of ice deformation and sliding movement. They also use “the fastest ice drill in the world” that can drill 5,000 feet into the Greenland Ice Sheet in eight hours.

“We don’t have a good theory for this type of sliding, but the data from this paper will allow us to work on an improved theory,” Humphrey explains.

As Maier says, “there has been some debate as to whether ice flow along the edges of Greenland should be considered mostly deformation or mostly sliding,” according to  Maier.

“This has to do with uncertainty of trying to calculate deformation motion using surface measurements alone. Our direct measurements of sliding- dominated motion, along with sliding measurements made by other research teams in Greenland, make a pretty compelling argument that no matter where you go along the edges of Greenland, you are likely to have a lot of sliding.”

The sliding ice does two things, according to Humphrey. It allows the ice to slide into the ocean and make icebergs, which then float away. Additionally, the ice slides into lower, warmer climate, where it can melt faster.

“In a really big melt year, the ice sheet might melt a few feet. It means Greenland is going to be there another 10,000 years,” Humphrey says.

“So, it’s not the catastrophe the media is overhyping.”

Paper

Written by Eddie Gonzales Jr. – MessageToEagle.com Staff