WASHINGTON (AP) — Scientists have witnessed the first modern case of what they call "river piracy" and they blame global warming.

Most of the water gushing from a glacier in northwest Canada last year suddenly switched from one river to another.

That changed the Slims River from a deep, raging river to something so shallow that it barely was above a scientist's high top sneakers at midstream. It also means the water from the glacier ends up in the Pacific Ocean instead of the Arctic's Bering Sea.

Study chief author Dan Shugar of the University of Washington Tacoma said it seemed to happen in about one day last May. A canyon formed at the end of the glacier, rerouting the water to another river.

The study is published in Monday's journal Nature Geoscience.