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Slims River: Climate change causes "river piracy" in Canada's Yukon

19 April 2017

It seemed to all happen in about one day past year - May 26, based on river gauge data, said Dan Shugar, a University of Washington Tacoma professor who studies how land changes.

Scientists have identified two main reasons why the glacier has retreated several kilometers from where it was in the last century.

For hundreds of years, the Slims River carried meltwater northward from the Kaskawulsh Glacier into the Kluane river and into the Yukon river toward the Bering Sea. Shugar said the unbelievable part is how quick the river piracy occurred.

"We went to the area intending to continue our measurements in the Slims river, but found the riverbed more or less dry", said James Best, a geologist at the University of IL.

Willis helped his colleagues by mapping, in precise detail (to 2-m resolution), the elevation of the landscapes through which the Slims flowed and now flows. A process that would normally take thousands of years or more happened nearly overnight in May 2016, according to the study by the University of Washington Tacoma. The river it used to fuel, the Slims River, had a floodplain a mile wide and a flow that ranged from.32 to.64 kilometres in width. "Our study shows there may be other underappreciated, unanticipated effects of glacial retreat". That's robbed the now largely parched Slims River and could decrease fish populations and the availability of nutrients downstream, the researchers predict.

Previous cases of river piracy may have taken place thousands of years ago or more, said Shugar in an interview with CBC News.

While people may inherently think of climate change as a gradual process, its effects need not be, he said, adding, "I think that has important implications for society". It's yet another example of climate change affecting our planet in unexpected ways.

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A vast glacier-fed river which flowed from Canada's Yukon province across Alaska to drain into the Bering Sea has disappeared in just four days in what scientists believe is the first observed case of "river piracy". When the team arrived to do observations they found a shallow lake where the river had once flowed, Popular Science reports. "A 30-meter (100-foot) canyon had been carved through the terminus [the outer edge] of the glacier".

The new outflow of the Kaskawulsh Glacier. Measurements indicate that the glacier has melt noticeably since 1899, as now it is at least 1.2 miles smaller than what it used to be. Now, the Kluane Lake level is dropping rapidly, which will put stress on the environment around the lake and could completely alter the geology of the area.

"We had a walk across the now exposed delta ... and sometimes you couldn't see further than five or 10 metres in front of you and the dust was getting caught in your throat".

Given the particular location of Kaskawulsh Glacier, the team suggests that other melting glaciers wouldn't necessarily produce similar instances of river stealing as they melt - but it could happen.

Rivers changing direction is relatively common, according to the scientists, but is usually caused by tectonic forces, landslides or erosion.

These events have occurred in a relatively sparsely populated wilderness area, and so will not have ramifications for large human populations - but they give a sense of just how dramatic and sudden climate-linked changes can be.

Slims River: Climate change causes