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It's not clear exactly how Bridge Glacier's retreat will impact the amount of electricity that can be generated downstream. But according to some scientists, it's becoming more apparent that we should start planning for less.
Time release mechanisms
Why are glaciers important to stream flow, and hydro, in the first place? Matthew Beedle, a PhD candidate at the University of Northern B.C. studying glaciers in relation to climate variability, describes glaciers as "nature's beautiful time-release mechanisms."
During the long hot days of late summer and early fall — just when precipitation drops off and after all the snow is already gone — is when glaciers start to melt. The gush of icy water replenishes the glacial watershed.
"This is a critical time for salmon coming upstream, and it can also be a critical time for power demand," says Beedle. "And glaciers are there to contribute to streamflow."
In a stable climate, glaciers "recharge" each winter when they accumulate more snow and ice. "But unfortunately, in a warming climate, you don't get that recharge," says Beedle. "So we're just drawing from that reservoir."
Beedle, who is also a Pacific Institute for Climate fellow, created the website GlacierChange.org to try and make the issue of melting glaciers, and the implications thereof, accessible to a more mainstream audience.
There are about 15,000 glaciers in British Columbia. In 1985, they covered 28,800 square kilometres. By 2005, they covered 25,000, a loss of 3,000 square kilometres, or about 11 per cent.
It stands to reason that a more rapidly melting glacier would mean more water — more streamflow — coming down the mountains. For a while, that was the case.
In 2006, Moore and a colleague looked at the August stream flow from 236 hydrometric stations in B.C. that captured water from a range of glacialized regions, including the Coast-Bridge system where the Bridge Glacier is located. They were surprising to find that August stream flow was lower than in previous decades — even though the glaciers were still losing mass.
Beedle explains that, as glaciers melt, they also lose surface area that is exposed to the sun. The melting slows, and at a certain point, the initial surge of water slows down. Moore's study is part of a body of research that all suggest the same thing, says Beedle: most watersheds in B.C. are already past this point. Though they continue to melt, the resulting runoff is less of a "surge" and more like a slow trickle.