Thursday, 20 January 2011 10:01
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| A pair of southeast-looking photographs, both taken from the same location 85 years apart near the retreating unnamed valley glacier that forms the East Fork of the Teklanika River, in Denali National Park and Preserve. Photo: Ronald Karpilo |
But Alaska's portion of the projected meltdown raises questions about the future of regional hydroelectric projects like the proposed multi-billion-dollar Susitna Dam, as well as Anchorage's drinking water source in Eklutna Lake and any other Alaska stream that relies on glacial melt for its summer flow.
If Alaska's climate continues to warm over the next 89 years as projected, summer runoff in glacier-fed basins like Susitna and Eklutna could initially soar by as much as 60 percent above the present during periods when the melt accelerates, said Regina Hock, a University of Alaska Fairbanks geophysicist who produced the study with lead author Valentina Radić, now a post-doctoral fellow at the University of British Columbia.
But after 2100, look out. As the source glaciers and ice fields recede, this annual summer surge could fall away. And eventually, perhaps, stop.
Alaskans hoping to build dams, secure drinking water or ensure future stream-flow for salmon and navigation should be asking: What then?
"Concerning both the Susitna dam and Eklutna Lake or any other hydropower scheme, it is essential to know how much total annual runoff will change," Hock said in an e-mail to Alaska Dispatch. "However, it seems that this has not really 'trickled in' yet in Alaska."
The research triggered similar concerns elsewhere in North America, according to a story posted last week by the Vancouver Sun.
"In Western Canada and the United States, 50 percent of glacier ice could disappear by 2100, which could have substantial impacts on regional power dams and water supplies," the Sun reported. "'For the long term, it's not good for the economy because there will be a drop in river run-off and less water in reservoirs,'" Radic told the Sun.
The state has endorsed the concept of building a 700-foot-tall dam and hydropower plant on the Susitna River as a major step toward generating half of the state's electric power with renewable sources by 2025. The project, under discussion for many decades, would cost an estimated $4.5 billion in 2008 dollars and create a 39-mile-long reservoir. Extensive studies still need to be done, with a round of public workshops expected in February.
Closer to Anchorage is Eklutna Glacier in Chugach State Park. Its summertime melt fills the stunning Eklutna Lake to the brim with pristine, azure water to sate the thirst of Alaska's largest city and power a historic hydro plant on the Knik River.
Most Anchorage residents take Eklutna Lake for granted. But will the time come when Chugach glaciers won't fill Anchorage's mountain lake for drinking and power? Will snowmelt alone cover local water needs?
Stay tuned, Hock said.
"This is actually the Ph.D. thesis topic of one of my graduate students, but no results yet. He will do exactly these calculations."
Alaskan glaciers to feed the sea big time
The research - conducted largely by Radić as part of her doctoral studies under Hock, first in Sweden and later at Fairbanks - examined the fate of 2,638 ice caps and 120,229 mountain glaciers under 10 different "state-of-the-art climate models" and then applied the results to 19 different regions around the globe.
It found that half of the world's smallest glaciers - 1,200 acres or less - will melt away entirely over the next nine decades. How much overall volume might be lost varied from region to region as well as from climate model to model, Hock explained.