Researchers plied the melted water from the ice sheet into the molines to better understand how it relates to the movement of ice.
According to a new study based on observation and first-hand discovery by a team including a geologist at the University of Arkansas, the melting water of the surface at the base of the Greenland ice sheet is called Mollins, much earlier than previously thought is big.
The additional volume can affect the stability of Greenland’s ice sheet and how quickly it slides towards the ocean.
The team studied the relationship between the diurnal variation of the size of the moulins and the water depth in them during the summer melting season. Scientists believe that as the water depth increases, and therefore the pressure inside, the moulins inside lubricate the base of the ice sheet and increase the speed of its movement toward the ocean, the way an ice cube is a thin layer of water. Slides easily on film. But until now, little was known about the actual size of the moulin and how much water they can hold.
Associate Professor of Geosciences Matt Covington said, “We compared our models with in-field observations of water levels and it seemed that we would need a really large amount of water variation inside the moulin. ” First author of the study published in the journal Geophysical research paper. “Then when we went back in the next year and found a moulin, it was huge. This was a case where the model made a prediction, and we went out in the field and it came out right. “
The team made two trips to the Greenland ice sheet in October 2018 and October 2019. During each trip, he used ropes and other climbing equipment at 100 meters in two separate moulins, almost reaching the water level.
“It’s intimidating,” said Covington, an experienced cave explorer. “You come back to shore and you just see blue snow as far as you can see, and then it’s blackness and there is also the occasional sound of crashing snow, which is very unnecessary.”
Scientists have long observed that Greenland’s ice sheet moves and melts the hot summer weather due to climate change. But researchers have little data to help understand the interactions between the base of the meltwater and the ice sheet. The team’s findings show how water interacts with the base of the ice sheet.
“We’re trying to understand the way the meltwater is interacting with the speed of the ice, and the main thing is that we’ve found that the water pressure within these moulin is not as variable as before. Was seen, and this is actually the result of a large amount of mollins, ”Covington said.
Reference: MD Callington, JD Gulley, c. Trunz, J. Mejia and W. “Molin Volumes Regulatory Regulate Subglacial Water Pressure on the Greenland Ice Sheet” by Gadd, 9 October 2020. Geophysical research paper.
DOI: 10.1029 / 2020GL088901