To better understand how volume relates to the motion of ice, researchers climbed into moulins, which drain water dissolved from ice sheets.
According to a new study based on observation and first-hand research by a team including a geologist from the University of Arkansas, molten water holes at the bottom of the Greenland ice sheet surface, called moulins.
The extra volume can affect the stability of the Greenland ice sheet and how quickly it slides towards the ocean.
The team studied the relationship between the size of the moulin during the summer melting season and the daily variation in the depth of water in it. Scientists believe that the depth of water has increased, and so the pressure, from inside, lubricates the base of the Moulins ice sheet and speeds up its movement towards the ocean, the way ice solid easily slides on a thin film of water. But so far, little was known about the actual size of the moulins and how much water they can hold.
“We compared our models to Dello with observations of the water level field and it seemed that the relatively small water variations we were looking at would require a really large size within the Moulins,” said Matt Wington, an associate professor at Geosins. The study was first published in the author’s journal Geographical research papers. “Then when we went back the next year and found a Moulin, it was huge. It was a case where the model predicted, and we went out into the field and it turned out to be OK. ”
The team made two trips to the Greenland ice sheet in October 2018 and October October 2019. During each voyage, they used ropes and other climbing equipment to turn 100 meters into two separate moulins, almost reaching the water level.
“It’s scary,” said veteran cave researcher Coving Wington. “You go back to the edge and see the blue snow go down as far as you can see, and then it’s blackness and there are also pertinent sounds of ice breaking, which is very vague.”
Scientists have long observed that Greenland’s ice sheet rotates and theorize that hot summers melting due to climate change could accelerate the movement. But researchers have little data to help understand the interaction between molten water and the base of an ice sheet. The team’s findings increase knowledge of how water interacts with the base of an ice sheet.
“We’re trying to understand how the melting water interacts with the motion of the ice, and the main thing we’ve found is that the water pressure inside this moulin doesn’t change as much as we’ve seen before, and that’s really the result. It seems. Moulins large volumes, ”Covington said.
Reference: MD Coving Wington, JD Glee, c. Trunz, j. Mejia and W. By Gade, 9 October October 2020, “Moulin Volume Regulation Subglacial Water Pressure on the Greenland Ice Sheet.” Geographical research papers.
ODI: DOT 10.1029 / 2020GL088901