Researchers have climbed into mounds that drain melt water from the ice sheet to better understand how volume relates to the movement of ice.
The holes that carry surface melt water to the base of the Greenland ice sheet, called molines, are much larger than previously thought, according to a new study based on first-hand observation by a University of Arkansas geologist.
Extra volume can affect the stability of Greenland ice և how fast it slides into the sea.
The team studied the relationship between the size of molines and their daily fluctuations in water depth during the summer thaw season. Scientists believe that the depth of the water և, consequently, the pressure of the molasses lubricates the base of the ice և increases its speed to the sea, just as ice easily slides on a thin layer of water. But so far little is known about the actual size of the moles, how much water they can hold.
“We compared our models to field water level observations. It seemed that we would need really large volumes inside the molines to produce the relatively smaller water fluctuations we saw,” said Matt Covington, the lead author of the study, published in the journal Geology. author: Geophysical research letters“Then when we came back the next year and studied the mule, it was a giant. That was the case when the model made a prediction, “we went out on the field, it turned out to be true.”
The team made two trips to the Greenland ice in October 2018 հ October 2019. During each trip, they used ropes and other mountaineering equipment to spread 100 meters between two separate algae, almost reaching the water level.
“It scares me,” said Covington, an experienced cave researcher. “You come back from the edge, you see the blue ice coming down as fast as you can see, then it ‘s dark, there’ s the occasional sound of ice crashing, which is quite disturbing.”
Scientists have long observed that the Greenland ice is moving, and the theory is that warmer summers are melting the weather due to climate change, which could accelerate that movement. But researchers have little data to help them understand the interaction between melted water and ice. The team’s discoveries add to the knowledge of how water interacts with the ice base.
“We are trying to understand how melted water interacts with the movement of ice. The main thing we have found is that the water pressure of these mounds is not as variable as it used to be. It seems to be the result of really large volumes.” in the malls, “Covington said.
Reference. “Moulin Volumes Regulate Glacial Water Pressure on Greenland Ice Sheet” – MD Covington, JD Gulley, C. Trunz, J. Mejia and W. Gadd, October 9, 2020. Geophysical research letters,
DOI: 10.1029 / 2020GL088901: