The river stolen by climate change

June 3, 2017

What impact could an unprecedented incident of ‘river piracy’ have on Canada’s Yukon territory?
When Jim Best and Dan Shugar visited the Slims River in Canada’s Yukon last summer, they made a discovery that caused the world to sit up and pay attention to this remote corner of North America. Instead of a flowing current, the pair found only a dry and dusty river bed. ‘The river had virtually dried up, and the lake into which the river flowed had dropped in water level,’ recalls Best, Professor of Sedimentary Geology at the University of Illinois.

They later discovered that the water had rerouted into a different river system – a phenomenon with the somewhat dramatic name of ‘river piracy’. Instead of flowing along the Slims river, through Kluane Lake, and eventually out into the Bering Sea, the water now travels primarily along the Kaskawulsh river, then south into the Alsek river, and ultimately into the Pacific Ocean.

Such a transformation has occurred numerous times throughout the planet’s geological history – often due to gradual erosion or the movement of a fault – but has never been observed to occur as suddenly, happening over just a few days in May 2016. ‘Geologists have seen [evidence of] river piracy before, but nobody to our knowledge has documented it actually happening [within] our lifetimes,’ explains Shugar, Assistant Professor of Geoscience at the University of Washington, Tacoma.