Hot Summer Shrinks Cascade Glaciers
Glaciers around the world are dwindling, but those in the North Cascade Range of Washington have been relatively stable for the last decade after a century-long trend of shrinking ice mass. Data collected by Earthwatch teams working with park geologists indicate that the record drought and heat of last summer melted Cascade glaciers considerably, but within the recent range of variability.
Jon Riedel and Robert Burrows (both of U.S. National Park Service), principal investigators of Earthwatch's Glaciers of the North Cascades project, presented their glacier data at the recent annual meeting of the Geological Society of America, in Seattle, Washington. Their measurements of four glaciers in North Cascades National Park indicate variations from year to year, with a net loss for two glaciers and a net gain for the other two over the last 11 years.
"We expect a lot of variability from year to year," said Burrows. "It is normal. This year was one of the hottest and driest in the 11 years of glacier monitoring at North Cascades and possibly the highest melt we have on record, but the summer was very similar to 1998 and 1994, so it is not an anomaly."
Glaciers around the world, from the Andes to the Alps, have receded in recent decades. A WWF report to the United Nation Framework Convention for Climate Change, meeting in Milan in December, states that an overall temperature rise of 4 degrees Celsius before the end of the century would eliminate all of them. Glaciers contain 70 percent of the world's freshwater reserves, and their loss would lead to water shortages for billions of people and sea level rises threatening coastal communities and habitats.
Like many other glaciers around the world, North Cascade glaciers have been retreating rapidly for more than a century. Riedel and Burrows estimate that glacier area in the North Cascades has decreased by nearly 45 percent in the last 150 years, with summer stream flow in one large watershed decreasing 30 percent in response.
"Despite the recent short-term trend toward stability, we expect the long-term trend of rapid glacier retreat in the North Cascades to continue into the next century," said Riedel.
Glacier mass balance in the North Cascades tend to follow a climate cycle called the Pacific Decadal Oscillation (PDO), related to and influenced by El Niño, which alternates between a warm/dry phase and a cool/wet phase. Data collected by Riedel and Burrows indicate that this year's drought may herald the beginning of a new warm/dry phase and the end of a six-year cool/wet phase.
Earthwatch teams working with Riedel, Burrows, and Jeannie Probala (also of U.S. National Park Service) were part of Earthwatch's Pacific Northwest Conservation Research Initiative (CRI). The CRI is made up of several research projects integrated to have the most impact on the conservation of natural and cultural resources in the Skagit River watershed, Washington, which is fed by Cascade glaciers.
"The glacier data tells us a lot about the changing environment," said Dr. Ralph Riley, field director of the Pacific Northwest CRI. "A large fraction of the late summer river flow in the Skagit River comes from glacier melt. If glaciers shrink further, there will be less volume of ice to supply late summer river flow. Salmon habitat will be lost, and the dams of the Skagit, which supply 30 percent of Seattle's electricity, will no longer be able to rely on late summer glacier melt."
Learn more about the Pacific Northwest Conservation Research Initiative.
Earthwatch Institute is an international nonprofit organization which supports scientific field research worldwide by offering members of the public unique opportunities to work alongside leading field scientists and researchers. The Institute's mission is to engage people worldwide in scientific field research and education to promote the understanding and action necessary for a sustainable environment.