Glaciers and Icefields

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Abstract

Glaciers and icefields are huge masses of ice, formed on land by the compaction and re-crystallization of snow, that move very slowly down slopes, or move outward due to their own weight. In Canada, an estimated area of 200 000 square kilometres, or about 2% of the country’s area is covered by glaciers and icefields. A huge quantity of freshwater is frozen in the polar ice caps and in high mountain glaciers. Glaciers and icefields are found in Western Cordillera and the mountains in the eastern Arctic. At present there are no reliable figures on the total number of glaciers in Canada. Glaciers exert a direct influence on the hydrologic cycle by slowing the passage of water through the cycle. Like groundwater, glaciers are excellent natural storehouses of water.

This map shows the distribution of glaciers and icefields in Canada, and also gives the names of some of their more important individual bodies. The text below discusses the distribution of these features, and then briefly comments on their impact on the environment and on the population.

Glaciers and icefields are huge masses of ice. Generally, glaciers flow in one direction, usually down a valley, while icefields and their larger equivalents, icecaps, flow outward in many directions. Glaciers and icefields cover about 10% of the earth's land area, mainly in Antarctica and Kalaallit Nunaat (Greenland). In Canada, an estimated area of 200 000 square kilometres, or about 2% of the country's area is covered by glaciers and icefields.

A huge quantity of freshwater is frozen in polar ice caps and in high mountain glaciers. Snow that is packed down over many years at high elevations becomes glacial ice, which slowly proceeds downslope like a frozen river, under the pull of gravity, and eventually melts to become part of streamflow at lower elevations. If the rate of melting is greater than the rate of accumulation, the glacier recedes; if it is less, the glacier advances.

Distribution of Glaciers and Icefields

Although glaciers and icefields are only found in two regions of Canada - the Western Cordillera and the mountains found in the eastern Arctic - and they are very numerous and widely-distributed within these areas. All ice features are remnants of the icefields of the last ice age, which peaked about 18 000 years ago.

In western Canada, glaciers occur at much higher elevations in the Rocky Mountains than in the wetter Coast Mountains. Mountain glaciers carve out a variety of distinctive features such as bowl-shaped features called cirques on the sides of mountains. The Arctic islands contain many glaciers and also have many large icecaps. Ellesmere, Baffin, Devon and Axel Heiberg islands contain huge icecaps which range up to one kilometre thick.

Table 1 summarizes the extent of icefields and glaciers. At present there are no reliable figures on either the total number of glaciers in Canada. The National Hydrology Research Institute of Environment Canada is in the process of identifying and measuring all glaciers. Tables 1a and 1b show the best available estimates for areas by region, and the number of glaciers for those areas surveyed to date.

Table 1a. Number and Area of Glaciers in Canada

Table 1b. Mainland Part of Canada: Glacier Data by Drainage Areas

Importance of Glaciers and Icefields

Glaciers exert a direct influence on the hydrologic cycle by slowing the passage of water through the cycle. Like groundwater, glaciers are excellent natural storehouses of water. One form of release by glaciers is in sudden outburst floods called "jökullhaups". Usually, the release is more gradual with glaciers having their highest rate of melting in the summer. Glacier-fed rivers, which include many of the largest rivers in Alberta and British Columbia, reach their peak flow during hot summer weather when other sources of water in these regions may be scarce. They are, therefore, extremely important to the relatively dry Prairie region as sources of water for irrigation, electric power, and uses by communities located close to these rivers.