quality:correction
Glaciers and icefields

Banff National Park has numerous large glaciers and icefields, 100 of which can be observed from the Icefields Parkway. Small cirque glaciers are fairly common in the Main Ranges, in depressions on the side of many mountains. As with the majority of mountain glaciers around the world, the glaciers in Banff are retreating. While Peyto Glacier is one of the longest continuously studied glaciers in the world, with research extending back to the 1970s, most of the glaciers of the Canadian Rockies have only been scientifically evaluated since the late 1990s. Glaciologists are now researching the glaciers in the park more thoroughly, and have been analyzing the impact that reduced glacier ice may have on water supplies to streams and rivers. Estimates are that 150 glaciers disappeared in the Canadian Rockies (areas both inside and outside Banff National Park) between the years 1920 and 1985. Another 150 glaciers disappeared between 1985 and 2005, indicating that the retreat and disappearance of glaciers is accelerating. In Banff National Park alone, in 1985 there were 365 glaciers but by 2005, 29 glaciers had disappeared. The total glaciated area dropped from 625 to 500 square kilometres (241 to 193 sq mi) in that time period.

The largest glaciated areas include the Waputik and Wapta Icefields, which both lie on the Banff-Yoho National Park border. Wapta Icefield covers approximately 80 km (31 sq mi) in area. Outlets of Wapta Icefield on the Banff side of the continental divide include Peyto, Bow, and Vulture Glaciers. Bow Glacier retreated an estimated 1,100 m (3,600 ft) between the years 1850 and 1953, and since that period, there has been further retreat which has left a newly formed lake at the terminal moraine. Peyto Glacier has lost 70 percent of its volume since record keeping began and has retreated approximately 2,000 m (6,600 ft) since 1880; the glacier is at risk of disappearing entirely within the next 30 to 40 years.

The Columbia Icefield, at the northern end of Banff, straddles the Banff and Jasper National Park border and extends into British Columbia. Snow Dome, in the Columbia Icefield is a hydrological apex of North America, with water flowing via outlet glaciers to the Atlantic, Pacific and Arctic Oceans. Saskatchewan Glacier, which is approximately 13 km (8 mi) in length and 30 km (12 sq mi) in area, is the major outlet of the Columbia Icefield that flows into Banff National Park. Between the years 1893 and 1953, Saskatchewan Glacier had retreated a distance of 1,364 m (4,475 ft), with the rate of retreat between the years 1948 and 1953 averaging 55 m (180 ft) per year. Overall, the glaciers of the Canadian Rockies lost 25 percent of their mass during the 20th century.