Tuesday, April 18, 2017

New Climate Change Term: "River Piracy" As Retreating Glacier Steals River

Here's a term I've never heard before in weather or climate circles but now suddenly it's a thing.

It's called "river piracy."  
Geoscientists stands in what used to be the Slims River in the
Yukon, which disappeared within four days last year
when a glacier melted back, diverting the water elsewhere.
Photo by Jim West/University of Illiinois via CBC

A waterway called the Slims River used to flow out of the Kaskawulsh Glacier in the Yukon.

The water in the Slims would flow north and eventually empty out into the Bering Sea, says the Canadian Broadcasting Corp or CBC. 

But the glacier has retreated so much that the water has found a newer, easier way to escape the melting glacier. It now flows south toward the Kaskawuish River and into the Gulf of Alaska, part of the Pacific Ocean.

The Slims River had flowed like it had for hundreds of years. It disappeared within four days last year - a millisecond in geological time.

This all was discovered last summer, when scientists headed north to study the glacier and the Slims River, only to discover there was no longer a Slims River.  In its place was just fine, sendiment, blowing around in the wind and causing a local dust storm.

Water always finds the easiest path to flow, so as the glacier retreated, it was able to find a steeper slope that took it out of the glacier and pushed it south into the Kaskawuish River.

The CBC said the scientists had never observed something like this before, at least in a way caused by a rapidly melting glacier. It can happen if, for instance, a large earthquake makes an area of land rise or fall abruptly, reversing the course of rivers in the earthquake zone.

This sort of thing might have happened the last time the world warmed up many thousands of years ago. But this time, climate change is believed to be a major factor in the disappearance of the Slims River.

For us down where lots of people live, the death of the Slims River in and of itself is not a big deal. However, glaciers are rapidly melting worldwide, and that causes sea level rises, which obviously affects shorelines all over the globe.

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