The glaciers of western Canada could soon follow their counterparts further south, with many disappearing before the end of the century, according to a study published in Nature Geoscience.
Contrary to climate change deniers' favorite meme du jour, glaciers around the world are retreating and many have disappeared entirely. For every glacier expanding as a result of increased snowfall, more than seven are in retreat from rising temperatures, sometimes combined with reduced precipitation.
Canada's north, with 105,000 km2 of glaciated territory, has the second largest area under permanent ice in the world, after Antarctica. This study, however, examined the future of the rivers of ice in British Columbia and Alberta. While much smaller, and therefore of less global significance than the ice sheets further north, the southwestern glaciers are important to the water supplies and electricity generation of these more densely populated regions.
“Most of our ice holdouts at the end of the century will be in the northwest corner of the province," said professor emeritus Garry Clarke of the University of British Columbia. "Soon our mountains could look like those in Colorado or California and you don't see much ice in those landscapes."
To predict the future of the region's glaciers, Clarke and his colleagues used the various greenhouse gas emission scenarios adopted by the Intergovernmental Panel on Climate Change (IPCC). They fed these into climate models for both temperature and precipitation.
Credit: University of British Columbia. The future of the Columbia Icefield under a high-emissions scenario.
The devastating changes that have happened to the mountain ranges of the western United States are easily visible from space. On the other hand, a cursory look at Canada's mountains show no signs of a similar decline. However, Clarke says this is an illusion. “Most glaciers are only 100 to 200 metres thick. They're losing volume but this loss we're seeing right now is a bit hidden.”
The observed loss of ice was compared with what Clarke's models predicted, showing a strong match that increased confidence in the ice melt projections—which suggest a drastic decline, with a loss of 70 ± 10% by 2100 relative to 2005.
Credit: Clarke et al. Modeled ice area by elevation for ten Canadian areas in 2005 fit well with observations.
B.C. and Alberta have 17,000 glaciers between them. They are a huge boon to the local economy because glaciers release water slowly through the warmer months, rather than in a rapid burst in spring.
The arrival of too much water in a rapid burst, with little to follow, will represent a major challenge to the hydroelectric dams from which the provinces draw most of their electric power.
There will also be ecological consequences. "These glaciers act as a thermostat for freshwater ecosystems," said Clarke. "Once the glaciers are gone, the streams will be a lot warmer and this will hugely change fresh water habitat. We could see some unpleasant surprises in terms of salmon productivity."
