Cascade volcanoes may be at greater risk for debris flows as climate warms
One of the most visible impacts of climate warming in the Pacific Northwest is the retreat of glaciers located on the flanks of volcanoes in the Cascade Range. As glaciers retreat, they expose steep, unconsolidated sediment that is prone to gullying and may fail catastrophically during intense rainstorms, resulting in debris flows. These flows can travel down slope for many miles at great speeds with enormous destructive potential. Such was the case in November 2006 when a record rainstorm initiated multiple debris flows on all major volcanoes in the northern Cascades. These flows destroyed roads and bridges and resulted in the unprecedented closure of Mount Rainier National Park for more than 6 months.
Scientists with the Pacific Northwest Research Station studied how, where, and under what circumstances such debris flows initiate. They discovered previously unreported links between receding glaciers, areas of stagnant and debris-mantled ice, and initiation zones for debris flows. These findings are helping the Forest Service and National Park Service reassess the risk to downstream infrastructure from such events and provide a potentially important example of how climate warming may be affecting mountain environments. These studies also are being coupled with downstream work by the U.S. Geological Survey to help explain changing patterns of channel aggradation and increased flooding potential for lowland areas surrounding Cascade volcanoes. The Christian Science Monitor and Los Angeles Times reported on these findings.
Forest Service Partners