Expect Alaska's glaciers to heat up soon
By Doug O'Harra
Alaska Dispatch
Most of the world's mountain glaciers and small ice caps will disappear or shrivel dramatically by the end of the century, with Alaska glaciers and ice fields shrinking by 25 to 60 percent over the next nine decades, according to new findings published last week in the journal Nature Geoscience. The study -- the most comprehensive ever done on the role of glacier wastage in sea level rise -- has already received extensive news coverage for its global perspective.
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?
