They detect a possible river 1,000 kilometers long below the Greenland ice sheet

They detect a possible river 1,000 kilometers long below the Greenland ice sheet

A scientific team performed numerous simulations to compare the dynamics of water in northern Greenland with and without valley segmentation.

They detect a possible river 1,000 kilometers long below the Greenland ice sheet

New computer models suggest that melt water originating deep inland Greenland could flow through an entire subglacial valley and out of the Petermann Fjord , along the island's north coast. Updating the ice sheet models with this open valley could provide additional information for future predictions of climate change, the researchers note in the journal 'The Cryosphere'.

Radar studies have previously mapped the Greenland bedrock buried under two to three thousand meters of ice . Mathematical models were used to fill in the gaps in the survey data and infer the depths of the bedrock.

Studies revealed the long valley, but suggested that it was segmented, preventing water from flowing freely through it. However, the peaks that divide the valley into segments only appear in areas where the mathematical model was used to fill in the missing data, so they could not be real.

Christopher Chambers and Ralf Greve, scientists at the University of Hokkaido's Institute of Low-Temperature Sciences, wanted to explore what could happen if the valley opens and melting increases in an area deep inland Greenland known for its melting. In collaboration with researchers from the University of Oslo, in Norway, they conducted numerous simulations to compare water dynamics in northern Greenland with and without valley segmentation .

The results show a dramatic change in how the melting water at the base of the ice sheet would flow, if the valley is truly open. A distinctive subglacial watercourse runs from the fusion site to Petermann Fjord, which is more than 1,000 kilometers away on the north coast of Greenland. The watercourse only appears when the valley segmentation is removed and there are no other major changes in the landscape or water dynamics.

The results are consistent with a long subglacial river,” Chambers explains, “but considerable uncertainty remains. For example, we do not know how much water, if any, is available to flow through the valley, and if it actually It comes out in Petermann Fjord or it freezes again, or it escapes out of the valley, on the way.

If the water flows, the model suggests that it could traverse the entire length of the valley because the valley is relatively flat, similar to a river bed. This suggests that no part of the ice sheet forms a physical blockage .

The simulations also suggested that there was more water flow into the fjord with a level valley base at 500 meters below sea level than when it was 100 meters below. Furthermore, when melt increases only deep inside in a known basal melt region, simulated discharge increases throughout the entire valley only when the valley is unblocked.

This suggests that a fairly fine relationship between the shape of the valley and the overlying ice may allow a very long waterway to develop into the valley.

“Additional radar studies are needed to confirm that the simulations are accurate,” says Greve, who has been developing the model used in the study, called the Simulation Code for Polythermal Ice Sheets (SICOPOLIS). This could introduce a system. fundamentally different hydrology for the Greenland ice sheet. Correct simulation of such a long subglacial hydrologic system could be important for future accurate ice sheet simulations in a changing climate. “

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