Major Canadian river vanishes in four days, in startling display of global warming’s impact

A major river that flowed from one of Canada’s largest glaciers vanished over the course of four days last year, scientists have reported, in an unsettling illustration of how global warming dramatically changes the world’s geography.

The abrupt and alarming disappearance of the Slims River , which spanned up to 150 metres at its widest points, is the first observed case of “river piracy”, in which the flow of one river is suddenly diverted into another.

For hundreds of years, the Slims carried meltwater northwards from the vast Kaskawulsh glacier in Canada’s Yukon territory into the Kluane river, then into the Yukon river towards the Bering Sea. But in spring 2016, a period of intense melting of the glacier meant the drainage gradient was tipped in favour of a second river, redirecting the meltwater to the Gulf of Alaska, thousands of kilometres from its original destination.

The continental-scale rearrangement was documented by a team of scientists who had been monitoring the incremental retreat of the glacier for years. But on a 2016 fieldwork expedition they were confronted with a landscape that had been radically transformed.

“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 Illinois. “The delta top that we’d been sailing over in a small boat was now a dust storm. In terms of landscape change it was incredibly dramatic.”