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Glaciers in North Cascades National Park, Washington, have retreated rapidly for most of the past 150 years, with a 44% reduction in ice cover. However, steady retreat has slowed periodically because of 5- to 10-year-long cold and wet periods, including 1997 to the present. More than 300 glaciers in North Cascades National Park and its contiguous units, Lake Chelan National Recreation Area and Ross Lake National Recreation Area, are vital components of Pacific Northwest aquatic and terrestrial ecosystems and hydrologic systems. These glaciers influence stream flows, flooding, soil development, vegetation distribution, water quality, and water delivery to hydroelectric projects, and are important indicators of climate change.
The National Park Service has monitored mass balance on three glaciers in North Cascades National Park since 1993 (four since 1995), tracking total winter snow accumulation and summer melt. In 2002, above-average winter snowfall led to minor growth of three of the four glaciers. Glaciers provided up to 40% total summer stream runoff and meltwater during extremely dry conditions in late summer and throughout the fall, helping maintain flows for threatened salmon species. Annual variations in balance match other glacier studies and climate records in the Pacific Northwest and are correlated to climate indexes such as El Niño, or Southern Oscillation, and the Pacific Decadal Oscillation.
Partners providing data, funding, and volunteers include the Earthwatch Institute, Seattle City Light, the USDA Natural Resource Conservation Service, and the U.S. Geological Survey. Natural Resource Challenge funding is integral to the stability of this program. In 2002 the Challenge also funded initiation of a glacier monitoring program at Mount Rainier National Park, with another to begin in one to two years at Olympic National Park.
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