Mountain Communities Dependent on Glaciers

While glacier melt in the Karakoram mountain range is threatening communities in Pakistan , the shrinking of glaciers of is having an impact on tourism, travel, and farming in North America. From national park tourists to ski town workers to communities downstream, glacier melt is beginning to affect how we work and play, and the changes observed in recent years could become even more dramatic.

The western United States is home to 8,303 glaciers, more than half of which are in Washington and California. Many of these glaciers have gotten considerably smaller during the past century because of climate change and a warming trend. For example, the glaciers of the Sierra Nevada in California are 60 percent smaller than they were in 1900, while the Cascade glaciers in Washington and Oregon shrank by 30 percent. Glacier National Park in Montana might need a name change before long as the glaciers of the Lewis Range have decreased in size by a whopping 66 percent.

Warmer temperatures can prompt annual glaciers melt to begin earlier in the spring, greatly increasing river flow and the likelihood of dramatic events known as glacial lake outburst floods that overwhelm roads, rivers, and communities. Glacial lakes formed by receding glaciers will eventually burst under pressure from melt and rainwater, sending a torrent of water and debris down the hillside.

In early November, 2006, a week of torrential rains destabilized a glacial lake that had formed below the melting glaciers of Oregon's Mt. Hood. A cascade of tons of water, rock and tree debris blasted through the forest and blocked a 10 mile stretch of Oregon Highway 35, the main artery to ski resort Mt. Hood Meadows. The ski resort, which had just opened days before, lost much of its business for one month as crews repaired the highway.

The glaciers of the Pacific Northwest are prone to lake and debris outbursts because many of them are located on dormant volcanoes, according to PSU Professor of Geography and Geology Andrew Fountain. Volcano mantle (the exposed crust) is composed of layers of gravel that is structurally weak, so as glaciers move down, they dig a trough through the gravel and dirt. When the glaciers recede, these basins can falter under the pressure of driving rains or melt water, letting loose the mixture of debris and water similar to what happened below Mt. Hood, Fountain says.

The ice-covered areas of the seven glaciers found on Mt. Hood have decreased in area by 34 percent during the last century, according to research by Keith Jackson, a graduate student in Geography at Portland State University. Mount Hood's glaciers are also a popular attraction for tourists, climbers and hikers, but Jackson says the views from the climbing trails are changing quickly, with the white of snow and ice being replaced by barren ground, rocks and assorted debris.

The opportunities for climbers who enjoy ascending glaciers with ice axe in handle will be reduced. "If there's no ice or snow, then there's no climbing," says PSU's Fountain, adding that Mt. Hood's glaciers provide water to apple and pear orchards in the Hood River Valley.

The Seattle area gets much of its drinking water from glacier melt, while streams in Montana's Wind River area also rely on summer snow melt, according to Fountain. These glaciers release snow and ice in August and September "just when the water is needed most," Fountain says, so further glacier melt could threaten the availability of summer river water for irrigation.

Glacier melt could also reduce tourism in national parks as views in some of the country's most scenic areas will no longer be as captivating. Reduction on travel could trickle down to affect the earnings of summer workers and nearby tourist towns.

The warmer temperatures of the past two decades threaten the ski and travel industries surrounding the American West's many glaciers. According to the University of Washington's Climate Impacts Group (CIG), the peak river runoff period from glacier melt is now as much as 20 days earlier in the spring in the western United States. Glaciers located at an altitude of around 3000 feet or less are more susceptible to increased melt due to warmer temperatures, while glaciers that are well above the melt line may receive even more snow in the winter, according to Fountain.

Climate change and shrinking glaciers will prompt rivers to flow more strongly in the winter and taper off during the summer months. The warmer weather (temperatures are expected to rise half of one degree Fahrenheit per decade) will shorten the ski season and increase the likelihood of rain during the winter months, according to the CIG. For example, at the Snoqualmie Pass ski area in Washington, the likelihood of opening the mountains for skiing by December 1 could decline by 50 percent by 2025, and the average ski season could be shortened by up to 28 percent.