Climate Change Reverses a River's Flow in Canadian Glacier

An aerial view of Kaskawulsh Glacier in Kluane National Park, Yukon, Canada. The UNESCO World Heritage site is undergoing rapid changes attributable to an altered climate. DEA/F. Barbagallo/De Agostini/Getty Images

If you need any further evidence of climate change's drastic impact upon the planet, consider this. Up in northern Canada, the massive Kaskawulsh Glacier is receding so rapidly that in May 2016, the water melting from it changed direction. Instead of flowing into the Slims River and then north to the Bering Sea, the water now is being captured by the Kaskawulsh River and flowing south toward the Gulf of Alaska.

That sort of shift is known to scientists as "river piracy" and "stream capture," and this is the first documented case of it in recorded history, according to the Washington Post.


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A Sept. 2, 2016 aerial photo shows the meltwater stream along the toe of Kaskawulsh Glacier, seen on the left, that is diverting fresh water from one river to the other.
Dan Shugar/University of Washington Tacoma

"People had looked into the geological record — thousands or millions of year ago — not the 21st Century, where it's happening under our noses," said Dan Shugar, a University of Washington Tacoma geoscientist, in a press release. He's also the lead author of an article on the phenomenon recently published in Nature Geoscience.

River piracy usually takes place over extremely long periods of thousands of years or even more. But the water rerouting caused by Kaskawulsh Glacier's retreat occurred in just a four-day period, following an unusually warm spring that caused melting waters to cut a channel through the ice, allowing the water to flow southward.

This type of river piracy isn't likely to happen elsewhere. But another of the study's co-authors, John Clague, of Canada's Simon Fraser University, said in the press release that the phenomenon "highlights the huge changes that glaciers are undergoing around the world due to climate change."

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A close-up view of the ice-walled canyon at the terminus of the Kaskawulsh Glacier, with recently collapsed ice blocks. This canyon now carries almost all meltwater from the toe of the glacier down the Kaskawulsh Valley and toward the Gulf of Alaska.
Jim Best/University of Illinois