Devika Desai
There may be a massive underground river running below Greenland, researchers say, fed by melting ice on the surface.
© Provided by National Post
This file photo taken on October 13, 2015 and obtained on November 24, 2015 by NASA shows the Heimdal Glacier in southern Greenland, captured from NASA Langley Research Center's Falcon 20 aircraft flying 33,000 feet above mean sea level during NASAs Operation IceBridge, an airborne survey of polar ice.
Scientists aren’t yet sure whether the river — nicknamed the ‘Dark River’ — actually exists. But evidence of a giant subglacial valley beneath the ice-covered country has led some to posit the theory of a giant river flowing 1,000 km from the deep interior of Greenland to Petermann Fjord in the country’s northwest.
“The results are consistent with a long subglacial river,” ice sheet modeller Christopher Chambers said in a press release by Hokkaido University in Japan, “but considerable uncertainty remains.”
Over the past 20 years, several studies have noted clues in the country’s topography that hint at the existence of trenches, valleys, even mega-canyons beneath the surface.
In 1998, researchers found two, roughly 75 km long, ‘elongated depressions in the surface of the ice connected by a “more than 1,000 km long, gently curving trench.’
By 2013, a ‘paleo-fluvial’ mega-canyon was identified — a remnant of a once-active water channel — extending from central Greenland to Petermann Fjord in north-west Greenland. Researchers, however, suggested that the valley could still have water flowing through certain sections, although observations are yet to be recorded.
While the studies present a glimpse of what could be a giant subglacial network beneath the surface, the major gaps in radar data obtained from satellite surveys conducted by NASA have left scientists uncertain as to how the valleys are connected and how water, in turn, would behave within them.
Scientists aren’t yet sure whether the river — nicknamed the ‘Dark River’ — actually exists. But evidence of a giant subglacial valley beneath the ice-covered country has led some to posit the theory of a giant river flowing 1,000 km from the deep interior of Greenland to Petermann Fjord in the country’s northwest.
“The results are consistent with a long subglacial river,” ice sheet modeller Christopher Chambers said in a press release by Hokkaido University in Japan, “but considerable uncertainty remains.”
Over the past 20 years, several studies have noted clues in the country’s topography that hint at the existence of trenches, valleys, even mega-canyons beneath the surface.
In 1998, researchers found two, roughly 75 km long, ‘elongated depressions in the surface of the ice connected by a “more than 1,000 km long, gently curving trench.’
By 2013, a ‘paleo-fluvial’ mega-canyon was identified — a remnant of a once-active water channel — extending from central Greenland to Petermann Fjord in north-west Greenland. Researchers, however, suggested that the valley could still have water flowing through certain sections, although observations are yet to be recorded.
While the studies present a glimpse of what could be a giant subglacial network beneath the surface, the major gaps in radar data obtained from satellite surveys conducted by NASA have left scientists uncertain as to how the valleys are connected and how water, in turn, would behave within them.
© Christopher Chambers The map shows the potential valley and possible river flowing from the interior of Greenland to Petermann Fjord.
We don’t know how much water, if any, is available to flow along the valley and whether it does indeed exit at Petermann Fjord, or is refrozen, or escapes the valley, along the way,” Chambers says .
Chambers and his team designed a ‘thought experiment’ in which they investigated the hypothesis that the valleys aren’t broken up but instead flow as a giant river, by simulating the state of Greenland via the SICOPOLIS method (SImulation COde for POLythermal Ice Sheets).
The simulations, they said, do support a waterway running from Greenland’s core to the sea. “The model results indicate that the valley follows a path down a gentle ice surface slope (Fig. 8 ) which would imply that the ice overburden pressure lowers as the valley progresses towards Petermann Fjord,” they wrote in their paper.
The simulation is plausible, they added, as the segmentation — rises in the subglacial valleys — seen in initial modelling might just be an illusion, due to misleading modelling in regions where little data has been recorded.
“The rises occur where data are interpolated to fill in gaps between where radar has obtained reliable data,” the authors wrote. “This suggests that the valley rises may not be real.”
Subsequently, if water is flowing, the model suggests it could cross the whole length of the valley as the region would be relatively flat, similar to a riverbed, with no physical barriers hindering the flow of the river, they added.
The findings are hypothetical for now, they conclude, but aerial surveys of the ice sheet topography may one day confirm the simulation results.
We don’t know how much water, if any, is available to flow along the valley and whether it does indeed exit at Petermann Fjord, or is refrozen, or escapes the valley, along the way,” Chambers says .
Chambers and his team designed a ‘thought experiment’ in which they investigated the hypothesis that the valleys aren’t broken up but instead flow as a giant river, by simulating the state of Greenland via the SICOPOLIS method (SImulation COde for POLythermal Ice Sheets).
The simulations, they said, do support a waterway running from Greenland’s core to the sea. “The model results indicate that the valley follows a path down a gentle ice surface slope (Fig. 8 ) which would imply that the ice overburden pressure lowers as the valley progresses towards Petermann Fjord,” they wrote in their paper.
The simulation is plausible, they added, as the segmentation — rises in the subglacial valleys — seen in initial modelling might just be an illusion, due to misleading modelling in regions where little data has been recorded.
“The rises occur where data are interpolated to fill in gaps between where radar has obtained reliable data,” the authors wrote. “This suggests that the valley rises may not be real.”
Subsequently, if water is flowing, the model suggests it could cross the whole length of the valley as the region would be relatively flat, similar to a riverbed, with no physical barriers hindering the flow of the river, they added.
The findings are hypothetical for now, they conclude, but aerial surveys of the ice sheet topography may one day confirm the simulation results.
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