NAME: Dr. Mauri Pelto
BIO: Dr. Mauri Pelto is a glaciologist who has worked in the field each year since 1981. He is also the Director of North Cascade Glacier Climate Project from 1984-present; author of the American Geophysical Union (AGU) Blogosphere, “From a Glaciers Perspective;” a professor in environmental science; and now Dean of Academic Affairs at Nichols College, Dudley, Massachusetts, United States.
PROJECT NAME: Observing the Disappearance of Glaciers in the North Cascades of Washington
DURATION: This is an ongoing project that began in 1984 with the expectation that it would last for 50 years.
What’s the purpose of your project?
Monitoring glaciers and alpine lakes and rivers to determine the impact of glacier loss on a watershed.
How are you setting up and testing your project?
We measure the mass balance and extent of 9 glaciers in the North Cascades annually. We measure the melt on each glacier and runoff from several of the glaciers. In addition, there is stream temperature data from other organizations in one watershed.
Any results yet?
We have observed over the last 33 years the loss of 25-30% of the total volume of the glaciers we monitor, and two have disappeared. We have identified the extent to which glaciers buffer summer low flow and high temperature conditions. Measurement of ablation and discharge immediately below Sholes Glacier quantifies the volume of glacier runoff to the North Fork Nooksack River, which provided more than 35% of total river runoff on 26 days in July-September, 2014, 37 days in 2015, and 19 days in 2016 (as of September 15, 2016). The ameliorating role of glacier runoff on discharge and water temperature is observed during 12 late summer warm weather events from 2009-2013 in the Nooksack Basin. The primary response to these events is increased discharge in the heavily glaciated North Fork and increased stream temperature in the unglaciated South Fork. During the 12 warm weather events, a +15% increase in discharge was observed during 11 events in the North Fork, and 0 events in the South Fork. For water temperature, all 12 events caused a 2°C rise in water temperature in the South Fork, but just 2 events caused this rise in the North Fork.
In the Skykomish River Basin, we measure the mass balance of three glaciers. There has been a 45% reduction in glacier area that has led to a 35-38% reduction in glacier runoff. The 38% reduction in glacier runoff did not lead to a significant decline in the percentage summer runoff contributed by glaciers under average conditions: the contribution has remained in the range of 1-3% from July-September. The glacier runoff decline impacted river discharge significantly only during low flow periods in August and September. The minimum mean monthly August discharge from 1928-2015 occurred in 2015, 2003 and 2005, when streamflow was 11.8 m³/s, 15.1 m³/s and 15.2 m³/s, respectively. From 1929-1985, streamflow was less than 14 m³/s during the glacier melt season on a single day in 1951. From 1986-2015, there were 264 days with discharge below 14 m³/s with 11 periods lasting for 10 consecutive days. In August 2003 and 2005, glacier ablation contributed 1.5-1.6 m³/s¹ to total discharge, or 10-11% of August discharge.
What has been the most interesting/challenging?
The substantial increase in algae development in streams and lakes near the glaciers has been surprising. Glacier retreat and intense melting has also made access to the glaciers more difficult. This is due to more exposed crevasses, more unstable, newly deglaciated sediments and steeper slopes on glacier margins that use to have thicker ice.
How will this project help society?
To rationally manage water resources, we have to understand how they are changing and to forecast how they will change. The glaciers are crucial to regional water resources for irrigation, hydropower, municipal supply and aquatic life, most notably salmon. The glaciers are small and occupy a temperate maritime climate setting, making them particularly sensitive to climate.
For further information regarding Dr. Mauri Pelto, please see his contribution to the “A Day in the GeoLife” series at Rock-Head Sciences: http://rockheadsciences.com/pelto-glaciology/.