Geoscientists Discover Mechanisms Controlling Greenland Ice Sheet Collapsehttps://phys.org/news/2019-07-geoscientists-mechanisms-greenland-ice-sheet.htmlIn research published in
Nature Communications, a group of scientists led by USF Distinguished University Professor Tim Dixon, Ph.D., uncovered a process that can control the "calving" of glaciers.
... "Iceberg calving has been challenging to model," Dixon said. "One of the big unknowns in future sea level rise is how fast Greenland falls apart, and iceberg calving is one of the least understood mechanisms."
... Scientists have long known that mélange can impede glaciers as they move toward the sea, but they haven't had the data to fully understand the phenomenon.
Dixon's team developed a new radar-based approach to precisely measure elevations of the mélange in front of Jakobshavn Glacier , a major outlet glacier on Greenland's west side. Using analytical techniques developed by Xie, the scientists measured the height of the mélange. The scientists found a thick mélange wedge pressed up against the glacier in late spring and early summer.
During this period, no icebergs calved, the scientists observed. Once the wedge thinned and melted by mid-summer, calving began in earnest.
"On the surface, this mélange is a subtle thing—it appears almost flat- but underwater, there are huge variations," Dixon said.
"It's really the underwater part that is pinning the glacier back and preventing it from calving. By precisely measuring the surface elevations, we were able to get a handle on the much bigger sub-surface variations, which define mélange thickness."