It’s hard to believe that an entire river can disappear in the space of days. The rare phenomenon is known as river piracy. Scientists observed the strange phenomenon for the first time in modern history. River piracy is a concept where one river’s flow is captured by another. The historical evidence available shows that the process takes thousands of years for it to occur. However, that was not the case with the Slims River which is fed by Canada’s Kaskawulsh Glacier which was co-opted in four days.
The timeframe was described by researchers as geologically instantaneous and it's likely to be permanent. Geoscientist Dan Shugar from the University of Washington Tacoma said that geologists have seen river piracy, but nobody to our knowledge has documented it happening in our lifetimes, adding that people had looked at the geological record thousands or millions of years ago not the 21st century.
David Shugar and fellow researchers made their way to the Slims River on a fieldwork expedition in the Yukon last August. On arrival, they found that Slims, which had a flow averaging about 480 meters wide previously had disappeared.David Shugar revealed that there was barely any flow whatsoever. It was essentially a long, skinny lake.
The researchers observed the water levels dropping day by day. The river gauges indicated that water levels had dropped sharply between 26 and 29 May 2016. In a bid to examine where all the water had gone, the team surveyed the area using drones and a helicopter, and the culprit in this case of river piracy became apparent.
In the last 300–350 years, Slims River was fed by north-running meltwaters from one of Canada's largest glaciers, Kaskawulsh Glacier. As the glacier retreated in recent years due to Earth's warming climate, a period of intense melting saw the flow of meltwater punch a new channel in the ice, rerouting the flow southwards via the Kaskawulsh River.
This implies that instead of ending up in the Bering Sea by way of Kluane Lake, the meltwater now runs in a southeast direction and eventually reaches the Pacific Ocean. The turnaround was massive and not only because it's the first time that river piracy has happened so quickly, but because it's the first case where scientists think the phenomenon happened due to human-caused climate change.
John Clague from Canada's Simon Fraser University revealed that the event was a bit distinctive given the peculiar geographic situation in which it happened, adding that in a broader sense it highlights the huge changes that glaciers are undergoing around the world due to climate change.