According to scientists, the mysterious “dark river” could flow 1,000 kilometers under Greenland

According to new research, a giant underground river fueled by melting ice could flow in a state of perennial darkness far below Greenland’s surface.

Dubbed the ‘dark river’, this hypothetical waterway – if it really exists, that is – can extend for 1,000 kilometers (620 miles), flowing from the deep interior of Greenland to the Petermann Fjord in the northwest of the country.

“The results are consistent with a long subglacial river,” says Christopher Chambers, an ice sheet shaper at the University of Hokkaido in Japan, “but considerable uncertainty remains.”

The suggested valley and possible river. (Chambers et al., The Cryosphere, 2020)

This uncertainty largely stems from significant gaps in radar data from aerial surveys over the Greenland ice sheet, which over the years have revealed fragmented glimpses of what appears to be a gigantic subglacial valley system that stretches beneath large parts of Greenland.

Numerous studies over the past two decades have suggested that such trenches, valleys or “mega-canyons” may lie hidden in the subglacial environment, and have also floated the idea that liquid water could flow to the bottom of the features.

However, due to data gaps, given the scarcity of air flights mapping these deep contours, it is not known whether all valleys are connected in a long meandering river or simply segments of disconnected phenomena, let alone how could behave down there.

“We don’t know how much water, if any, is available to flow down the valley, and whether it actually flows out at Petermann Fjord or is refrozen, or flows out of the valley, along the way,” says Chambers.

In a new study, designed as a “thought experiment,” Chambers and his team explored the hypothetical possibility that the valley is not divided into separate parts, but flows continuously in a long river.

Such a possibility is plausible, they say, given that the segmentation seen in modeling before could be an illusion: phantom elevations resulting from misleading models in regions with little data, rather than territorial characteristics.

“The increases occur where the data is interpolated to fill the gaps between where the radar has obtained reliable data,” the authors write in their new paper. “This suggests that the valley rise may not be real.”

In the new modeling, the researchers assumed that the dark river was indeed a continuous feature. Based on this scenario, simulations suggested that the watercourse flows from the center of Greenland to the sea, with liquid water flowing through the path uninterrupted.

“Along its length, the valley path gradually progresses along a slope of the ice surface, causing a drop in the ice cover pressure that could allow water to flow along its path,” the team writes.

While the results remain hypothetical for now, the researchers think future aerial surveys may one day be able to confirm the simulations.

If so, it would not only tell us that the dark river is real, it would also mean that we have reached a new level of ability to model the behavior of the Greenland ice sheet – an extremely complex and mysterious body that is predicted to have a major impact on the future sea level rise.

The results are reported in The cryosphere.