In 4 days, a river that had flowed for millennia disappeared

Posted by Jeff on Apr 27, 2017 @ 7:01 am in Conservation | 0 comments | Last modified: April 26, 2017

The latest consequence of climate change is rivers “pirating” each other’s water.

Nearly a year ago, scientists noticed that the water level of the Slims River in British Columbia was extremely low. So they hopped into a helicopter and flew upstream to investigate. What they found startled them: A second, more powerful river, the Kaskawulsh, had stolen the Slims River’s water for itself. Three days later, the Slims was gone entirely.

For centuries, meltwater from the Kaskawulsh Glacier had fed both the Slims and Kaskawulsh rivers. But in the past 100 years, the glacier has retreated as a result of climate change. And in early 2016, the glacier receded so much that the Kaskawulsh River, with a gradient nearly five times steeper than the Slims, was perfectly poised to catch and divert the Slims.

In a recent paper, scientists say this was most aggressive instance of “river piracy” — one river capturing and diverting the flow of another — on record. It’s also a troubling example of how swiftly climate change is affecting rivers and other bodies of water.

“Most people think of climate change as gradual and its consequences as gradual, but one of the things we were able to show here is you can produce some rather dramatic changes, suddenly,” said John Clague at Simon Fraser University in British Columbia, one of the authors of the paper. “And these unforeseen, sudden changes are much harder to deal with than ones that play out slowly.” In particular, researchers like Clague are worried about sudden changes to the chemistry and nutrient supply of a lake once fed by the Slims.

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