Date:22 April 2017
Climate change has a sent the Kaskawulsh river in the Canadian Yukon flowing the opposite direction. The finding, from the University of Washington, shows this is one of “the less anticipated shifts”.
By David Grossman
The Kaskawulsh Glacier is located on the Canadian side of the St. Elias Mountains, which extends into America and is the highest coastal mountain range on Earth. The Glacier is large, covering around 15,000 square miles. It feeds into two rivers, the Kaskawulsh River and the Slims River, supposedly named after a horse that died there during a minor gold rush in 1903.
However, the glacier retreated last spring to such a degree that what’s normally a geologic event happened in four days. It’s called “river piracy.” The glacier retreated so far back that the lake that was feeding the Slims changed its outlet, and now solely contributes to the Kaskawulsh River.
“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.”
Shugar, as well as co-authors Jim Best at the University of Illinois and John Clague of Simon Fraser University, didn’t expect to find the Slims River gone. They had expected to study it, but when they arrived last August, it just wasn’t there. “There was barely any flow whatsoever. It was essentially a long, skinny lake,” Shugar said. “The water was somewhat treacherous to approach, because you’re walking on these old river sediments that were really goopy and would suck you in. And day by day we could see the water level dropping.”
Shugar and his colleagues decided to study this change instead, going back 300 years into the river’s history. “Meltwater,” he says, “was flowing through that canyon from one lake into another glacial lake, almost like when you see champagne poured into glasses that are stacked in a pyramid.” The second lake drains via the Kaskawulsh in a different direction than the first. The situation is exacerbated naturally by the fact that the toe of the river sits on a geologic divide.
“The event is a bit idiosyncratic, given the peculiar geographic situation in which it happened, but in a broader sense it highlights the huge changes that glaciers are undergoing around the world due to climate change,” says Clague, who also points to that “Earth’s glaciers are becoming markedly smaller, and that can only happen in a warming climate.”
Much of the attention in climate change focus on sea-levels, which is understandable given how we’ve underestimated how much they’ve risen. But glaciers are also affected, which is why NASA recently created a tool to track their melt across the world. It’s unclear if the tool will last in a new Administration focused on removing all mention of climate change from the federal government.
Source: USA Today
This article was originally written for and published by Popular Mechanics USA.