“We’re past the tipping point for the glaciers in the Canadian Rockies,” says John Pomeroy, professor and Canada Research Chair in water resources and climate change at the University of Saskatchewan.
Pomeroy says over the last few decades, almost all the world’s glaciers have shrunk and the rate of decline is accelerating.
“Even if somehow, magically, we’re able to stop global warming tomorrow and return the atmosphere to more normal CO2 concentrations, we would lose most of the Rockies’ glaciers.”
Hot weather like we experienced last summer doesn’t have an immediate impact on glaciers but will be seen in melt rates of the future.
Pomeroy believes the massive Columbia Icefield, located between Banff and Jasper, will survive past the end of the century.
He sees a less promising future for the Peyto Glacier, about 45 kilometres north of Lake Louise, which could all but disappear by 2030.
“The glaciers, as you can see from the highways, are probably finished. By mid-century, the Icefields Parkway, people may begin to wonder why it’s named that.”
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High rate of melting
Warmer winters aren’t the only factor driving glacier melt.
A deep purple algae, likely linked to forest fires, has been collecting on Canadian glaciers over the last few decades. The algae looks like dark dust and causes the glacier to absorb solar energy, causing even more rapid melting.
“I went through my photographs in the 1970s and ‘80s just to make sure I wasn’t dreaming,” says Pomeroy.
“Glaciers were very, very white back then. And they’re not like that now.”
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Pomeroy says the algae problem is still not fully understood but there is a connection between ice and fire.
After the severe fire season in 2018, glaciers remained dark well into 2020, he adds.
“The algae has colonized the glaciers because of the forest fires, soot, the organic matter, the carbon,” he says.
“Perhaps it occurred with the soot, perhaps they were always there, but they didn’t bloom as much because they didn’t have the food source before. But they certainly are now.”
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What does all this mean for our water supply?
Kavanaugh says glaciers keep our rivers flowing when other water sources dry up, like late summer when the snowmelt is gone and rainfall is at its weakest.
“They carry us through the hottest months into the winter.”
During particularly hot and dry years — like last summer, for example — glacier-fed rivers can actually see higher-than-normal flow.
“Though the streams that relied on the snowpack and groundwater dropped to very, very low levels, the streams that were fed by glaciers — like the Athabasca River or the North Saskatchewan — had very high flows,” Pomeroy says
The next few decades could be marked by high flows in our glacial rivers, which will continue as long as the glaciers are voluminous enough to contribute a lot of water, Kavanaugh says.
“We might have a 20-year window of this much water and then it will start to fall off a cliff,” he says. “How much water is flowing through the river as a function of that time of year is going to start changing remarkably.”
As we see a change in precipitation from snow to rainfall, snowpacks will melt earlier, meaning streamflow will shift earlier.
“We can look a little bit south and see what happens in Montana and Idaho already as they’ve essentially lost their glaciers,” says Pomeroy.
“Things get very, very dry when they get into a drought period.”
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lot more on:
https://www.cbc.ca/newsinteractives/features/glacier-melt-is-past-the-tipping-point-in-the-canadian-rockies-and-thats-a-big-problem
