Blue Legacy: The Recent History of Glaciers in the North Cascades


Time:  4pm PT  /  5pm MT  /  6pm CT  /  7pm ET
Host Organization:  
North Cascades Institute — Sedro Woolley, WA

What do you do if you are a young Midwestern college graduate holding a degree in geology and a yearning for adventure, wilderness and outdoor work in the West? “You go to where the action is,” says Jon Riedel, and for him, that meant the North Cascades. Fresh out of the University of Wisconsin at Madison, Riedel landed in the upper Skagit Valley first as a Student Conservation Association volunteer in the summer of 1980, and he returned for several summers after, studying the unusual landforms in remote Depot Creek for his masters thesis. Many years later, Riedel is a long-time geologist with the National Park Service and a leading expert on glaciers in the Pacific Northwest. Our region's glaciation history is unique, having been shaped by both local alpine glaciers that grew from mountains down to valleys as well as by continental icesheets moving in slowly from Canada to smother the range in ice more than a mile thick. One of Riedel’s most important contributions to the understanding of the North Cascades is his Glacial Monitoring Program, which he started in 1993. The study records seasonal surface accumulation of snow and the loss of snow and ice to melting—annual volume change, or mass balance—of four glaciers at different elevations with different aspects draining to different rivers. Riedel and his team visit the glaciers at least twice a year to take measurements against their melt stakes. They also survey the total area of all glaciers in the national park every 20 years. “Glaciers are dramatic indicators of climate change,” explains Riedel. “They are sensitive to temperature because that is what determines what form of precipitation falls—snow versus rain— as well as the length and magnitude of the melt season.” For example, the one degree Celsius increase in temperatures over the last century has melted half of the glacial area in the North Cascades. In this online course, Jon will walk us through the recent history of glaciers in the North Cascades, beginning with the end of the last ice age to the present rapid decline. We'll learn why glaciers are important in this region, then move on to a photographic journey of change in glacier area in the last century. Our focus will shift to the Glacier Monitoring Program that tracks seasonal changes in volume on eight glaciers in Washington's national parks. Jon will present an example of how we use the monitoring data to track changes in the glacial contribution to water resources in Skagit Valley, and conclude with a long-term perspective on glacier change from the geologic record. Learn more here.