Water Blisters Trapped Beneath Greenland’s Thick Ice Sheet Could Provide

Water “blisters” trapped beneath the thick interior of Greenland’s ice sheet could provide critical insight into the hydrological network coursing deep below Earth’s second largest body of ice — and how it might be destabilized by climate change, according to a new study.

Each year, thousands of natural meltwater lakes form on the surface of the ice sheet’s high-elevation interior, where ice can be more than a half-mile thick. As these lakes drain, they form large water-filled cavities between the ice and the bedrock.

By combining field observations with mathematical models and laboratory experiments, Princeton University-led researchers discovered that these blisters push the surface of the ice upward, then cause it to gradually drop down as the water permeates into the subglacial drainage system, according to a report in the journal Nature Communications.–nc-state-live-/–nc-state-live-/,49270925.html

The team shows for the first time that the rise and fall of the ice sheet caused by rapid lake drainages can be used to estimate a property known as transmissivity, which characterizes the efficiency of the water networks that form between the ice and the bedrock. Lake drainage presents a new tool for gauging transmissivity beneath inland regions of the ice sheet, where transmissivity is otherwise difficult to measure, the researchers reported. They found that transmissivity can increase by as much as two orders of magnitude during Greenland’s summer melt season.

Meltwater-filled cavities push the surface of the ice sheet upward (left), then cause it to gradually drop down (right) as the water permeates the subglacial drainage system. This rise and fall can be used to estimate a property of the subglacial drainage system known as transmissivity. Credit: Ching-Yao Lai, Department of Geosciences

The findings could shed light on how climate change will affect Greenland’s vast frozen interior as the planet warms and surface melting increases, said first author Ching-Yao Lai, an assistant professor of geosciences and atmospheric and oceanic sciences at Princeton. Water from surface melting can act as a lubricant, she said, causing the glacier to slide more easily across the bedrock.

Existing research has shown that a major way for surface melting to impact the stability of the Greenland ice sheet is by meltwater lubricating the ice-sheet bed, Lai said. The majority of these studies, however, have focused on low-elevation areas where the ice sheet is thinner. Previous studies also have suggested that increased surface melt could accelerate the velocity of the high-elevation, interior ice sheet, but these findings are based on computational models, rather than observations, Lai said.

The paper in Nature Communications provides a rare, observation-based glimpse into the largely inaccessible water networks underlying Greenland’s high-elevation ice sheet. The study was supported by Princeton’s High Meadows Environmental Institute (HMEI) and the HMEI Carbon Mitigation Initiative.

Leave a Reply

Your email address will not be published. Required fields are marked *