Glaciers and Climate Change

The Rocky Mountains attract hundreds of thousands of visitors each year. Most are tourists, drawn by the spectacular beauty of alpine glaciers and icefields, but others are federal government scientists who have come to investigate the links between glaciers, climate and Canada's water resources.

Glaciers are an important part of the Canadian landscape. Canada's surface terrain has been defined by a million years of glacier and ice-sheet fluctuations, and today only Antarctica and Greenland have more glacier ice. Glaciers have much to tell us about past and present environmental conditions. Analysis of ice cores taken from glaciers reveals a layer-by-layer record of past temperatures, pollution levels, and atmospheric conditions. This information about past climates helps researchers understand variations in today's climate, and predict the effects of changes in the future.

In certain parts of the country, glaciers play a key role in supplying communities with water for irrigation, drinking, and hydro-electric power. The runoff they provide is essential also for maintaining river and riparian habitat. Concern is growing about the impact that changes in glaciers may have on water resources in western Canada. To learn more about what those impacts might be, scientists at Environment Canada's National Water Research Institute (NWRI) in Saskatoon have been working with glaciologists from the Geological Survey of Canada at Natural Resources Canada to study the Saskatchewan-Nelson River Basin in the Canadian Rockies.

The eastern slopes of the Rocky Mountains have approximately 1 300 glaciers, which, by many estimates, have lost 25-75 per cent of their mass since the peak of the Little Ice Age, around 1850. Researchers compared fluctuations in glacier mass in the last century with modern fluctuations to determine if there is a recognizable pattern or trend in the volume of water released by glaciers over this period. Past fluctuations were reconstructed from old maps, photographs, analysis of direct measurements, and data on glacier form and composition. Modern fluctuations were determined using remote-sensing data, measurements of mass balance, and data from the Canadian Glacier Inventory at the NWRI.

It had been thought that climate warming would cause an increase in melt-water from glaciers in the short to medium term. Instead, scientists found that a pronounced reduction in the area of glacier-cover over the last 50 years has already led to reduced yields of water during critical periods in the highly glacierized sub-basins of the Saskatchewan-Nelson River Basin. One critical period is from August to December each year, when a diminished water supply would not only hamper hydro-power operations, but would also affect the spawning of several species of fish, including the endangered Bull Trout. To build on these results, the researchers are now planning a more extensive study of all the major contributing basins of the Rocky Mountain eastern slopes.

NWRI scientists are also part of a research team investigating the impacts of climate change on the glacier reserves feeding the Columbia River, a system that runs through British Columbia, Washington and Oregon, and supports an extensive complex of hydro-electric developments. Their first step is to determine changes in glacier resources since 1850 and compare these with historical changes in climate. Using an atmospheric-hydrologic model, researchers will then try to predict how these reserves will respond to climatic variations in the future--information that will assist resource managers in maximizing power production and minimizing downstream hydrologic and ecological impacts.

Environment Canada and Natural Resources Canada have recently amalgamated their glacier science expertise in a National Glaciology Program. The new program will improve our understanding of how Canada's water resources are responding to climate change, enable us to develop adaptive strategies for managing these resources, and provide better information on the movement, deposition and volume of pollution in our environment.

The eastern-flowing rivers of the North Saskatchewan Basin, showing glacier coverage.

From space, the bright white patches of snow and ice in the earth's polar regions and mountain chains shine like beacons in the darkness, their brilliant surfaces reflecting the sun's energy. This process acts as a global air conditioner, keeping the surface temperature of the planet in balance.

According to recent studies by Environment Canada scientists, warming trends caused by climate change could have a dramatic effect on these regions. If atmospheric levels of greenhouse gases continue to rise, experts say global average temperatures may increase 3-5 degrees Celsius. In snow-covered mountainous regions, warmer temperatures may melt snow, reduce the reflective snow cover, and allow more solar energy to be absorbed by the earth's surface. As surface temperatures heat up, they will cause even more melting and, consequently, even warmer surface temperatures--a circular chain of events known as "positive feedback."

This cycle could have a dramatic effect in mountainous regions of British Columbia. Higher temperatures and less snow could upset sensitive ecosystems, allowing trees and other vegetation to invade open areas that are essential habitat for certain species of wildlife, and could leave some ski areas in the Rockies and Southern B. C. without enough snow to operate. They could also have a significant negative impact on water resources, which rely heavily on snow melt, particularly in the mid to late summer. Domestic water supplies could be hit hard, as could migrating salmon if water temperatures become too warm.

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