The Slims River in northern Canada has dried up in just four days, according to a scientific study published Monday.
River piracy is when the water from one river is "stolen" by another.
Scientists have witnessed the first modern case of what they call "river piracy" and they blame global warming.
This example of river piracy is unique not only because it is occurring in modern times, but it happened as a result of the glacier's position.
The Slims River runs from the Yukon down to the Bering Sea, while the Alsek River hits continental waters in the Pacific Ocean. But in spring 2016, a period of intense melting of the glacier meant the drainage gradient was tipped in favor of a second river, redirecting the meltwater to the Gulf of Alaska, thousands of miles from its original destination.
The stream at the base of the Kaskawulsh glacier that helped behead the Sims river in Canada. "We went to the area intending to continue our measurements in the Slims river, but found the riverbed more or less dry", said University of IL geologist James Best. The delta top that we'd been sailing over in a small boat was now a dust storm.
Given that these mountainous landscapes were carved by glaciers over millennia, geologically it's considered "an absolutely instantaneous event", said Best. Satellite images also showed that the valley, where the river once flowed, has mostly been dried out and replaced by sediment. When the shift abruptly reduced water levels in Kluane Lake, the Canadian Broadcasting Corp. "What we found was the glacial lake that fed Slims River had actually changed its outlet", Shugar explained. This phenomenon is known as "river piracy".
Rivers are inconstant. They wiggle like a steady trickle flowing down a window, forming and wiping out meanders and oxbows and levees and islands.
But when scientists returned past year, the river was not only shallow, but still as a lake.
For the first time on record, climate change has completely changed the route of a river.
The unusually warm spring resulted in the meltwater cutting a canyon through the ice and diverting water into the Alsec River, which flows to the south and into the Pacific, robbing waters that were supposed to go north. Last summer, Kluane Lake dropped a full metre below its lowest ever recorded level for that time of year.
The underlying message of the new research is clear, Shugar said. The lake that it fed - Kluane Lake - is 72km long and more than 76m deep in places.
Gerard Roe, co-author of the study and a professor at the University of Washington in Seattle in the U.S. state of Washington, told AFP today that the Slims riverbed had dried up in only four days.
"Would this event have occurred without anthropogenic climate change?" With the riverbed exposed, Dall sheep are now making their way down from a national park to eat the vegetation that now grows there, wandering into territory in which they can be legally hunted.
The redistribution has already taken its toll on both regions' ecosystems, with disruptions to lake chemistry, fish populations and the behaviour of wildlife reported.
This dramatic effect of global warming was documented by team of experts who had been following the glacier and its steady retreat. What's remarkable bout this particular study is that it documents the less than anticipated effects of climate change on our environment.