Major rivers that are vital to prairie farms and communities have their source in Rocky Mountain alpine glaciers that are receding, but the effect on river flows is unclear.
Masaki Hayashi of the University of Calgary’s department of geology and geophysics said melt water from glaciers takes a complicated, circuitous path from the Rockies to the Bow and Saskatchewan River systems.
It often soaks into the rocks and goes underground before surfacing hundreds of years later in streams, making it difficult to estimate its contribution to rivers and watersheds.
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“There is a time lag between what happens on the glacier and what happens in the stream,” he said.
Hayashi is conducting research at Lake O’Hara in British Columbia’s Yoho National Park to study the effect that shrinking glaciers will have on flows in streams.
He will explore the pathways and storage processes from glacier to mountain stream before building models to predict the impact of climate change on the amount of water in streams.
Many scientists agree that the majority of glaciers, including those in the Rockies, are melting and retreating. Few can agree on the effects of this recession, with some believing it could result in flooding or decreased water resources.
Hayashi said further scientific study is needed before jumping to conclusions about the negative effects.
That’s a view shared by John Pomeroy, director of the Centre for Hydrology and Canada research chair in water resources and climate change at the University of Saskatchewan in Saskatoon.
Canadian studies show that the impact of glacier recession on the total amount of water in rivers is relatively minor.
“It’s certainly nothing like a panic situation,” he said.
Pomeroy said glacier recession is unlikely to have a large impact on prairie irrigation. At most, glaciers contribute 0.1 percent annually to Alberta’s Bow River flow, based on his graduate student’s recent studies with Environment Canada. Glacier melt water shows up in late summer and early fall when it is least needed for irrigating crops.
Pomeroy noted that many confuse glaciers’ contribution to river flows with that from melting mountain snow pack.
Snow melt occurs on glaciers and on non-glaciated mountain terrain through much of the summer. Rain from May to July in the Rockies and snow melt supply one-half to two-thirds of the flows.
“Glaciers are like a high mountain ground water supply,” Pomeroy said. They’re more like a reserve for dry years.”
The World Meteorological Organization and the United Nations Environment Program established the Intergovernmental Panel on Climate Change in 1988. The panel reported in 2002 that global warming could cause snow melt-dominated watersheds in western North America to experience earlier spring peak flows, reductions in summer flows and reduced lake levels and outflows for the Great Lakes-St. Lawrence River system.
