The Kaskawulsh Glacier in northern Canada has retreated about a mile up its valley over the past century.
In 2016, its retreat triggered a major geologic event: meltwater from the glacier that had previously flowed north toward the Slims River and Bering Sea, retreated so far that it changed course. Now, it flows south to the Kaskawulsh River and Gulf of Alaska.
This capture of one river’s flow by another, documented in a study led by the University of Washington Tacoma and published April 17 in Nature Geoscience, is the first known case of “river piracy” in modern times.
“Geologists have seen river piracy, but nobody to our knowledge has documented it happening in our lifetimes,” said lead author Dan Shugar, a geoscientist at the University of Washington Tacoma. “People had looked at the geological record — thousands or millions of years ago — not the 21st century, where it’s happening under our noses.”
Gerard Roe, a professor of Earth and space sciences at UW, is a the co-author. Last year, he published a technique that showing a 99.5 percent probability that this the Kaskawulsh Glacier’s retreat is showing the effects of modern climate change.