Glacier Surveys in Olympic National Park

by Future Park Leaders of Emerging Change intern Justin Pflug, University of Washington

Hoh Glacier on Mount Olympus

The Olympic glaciers, centered in Olympic National Park of Northwest Washington, serve as vital late-summer sources of water for a number of sensitive ecosystems and species. These thin and relatively small glaciers reside in a low-latitude, low-elevation, precipitation-dominant, and temperate maritime climate. In addition, the snow cover in this region is highly sensitive as it tends to form within a few degrees of the freezing point. Slight increases in temperature can cause this precipitation to fall in the form of rain, leaving glaciers snow-free and available to melt for longer periods in the summer. The winter of 2015 was representative of Washington climate-change scenarios with a 2° C increase in temperature. This provided an ideal opportunity to analyze glacier distribution, glacier melt, and the downstream contribution from Olympic glaciers impacted by climate change.

The Olympic glaciers were outlined using airborne and satellite imagery to determine the extent of the glaciers following 2015. Digital Elevation Maps were also used to calculate the amount of water released and the change in glacial mass during the 2015 melt event. Multiple models are currently being used to quantify the daily glacier melt and downstream contribution.

Project results indicate that there was a loss in 36 glaciers and an 18% reduction in surface area from 2009 to 2015. The rate at which the glaciers are receding doubled in the 1980-2009 period and nearly quadrupled in the 2009-2015 period. Glaciers lost approximately 35 million m3 of water, or enough water to fill over 130,000 Olympic-sized swimming pools during the 2015 melt. The Olympic glaciers are highly sensitive and visitors, staff, and wildlife will see alterations in stream temperature, flows, and timing as climate change continues.

Debris-stake surveys performed in the neighboring South Cascade range. Debris was analyzed here to make debris-covered glacier surfaces more easily identifiable from airborne imagery.