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Climate Change and Water Supply

Climate change is not just a theory. Over the past century, average temperatures in the Prairie Region increased by approximately 1°C, but temperature rise in some areas is greater. Changes in temperature affect precipitation, wind patterns and humidity, all of which impact surface water supplies.

The warming climate is shrinking the glaciers in the Rocky Mountains that feed the sources of the Saskatchewan River system, the most important water source in Saskatchewan. Research shows the reliability of water flowing from its glaciated headwaters has been declining since the mid-20th century. The Athabasca Glacier, for example, is currently losing 16 million cubic metres of water per year more than it regains from snowfall.

Research indicates river flows in some parts of the prairies have declined by 40 percent over the past 75 years. River flow in the late summer and fall is largely dependent on glacial melt. Much of the spring and early summer flow results from runoff from winter snows in the mountains and precipitation throughout the river basin. Evidence is that snowfall, both in the mountains and elsewhere in the basin, has decreased in the last 100 years. Summer precipitation is up slightly in the Prairies, but rates of evaporation due to higher temperatures tend to neutralize that increase.

Climate change predictions show an average temperature increase of 3°-5°C in the southern Prairies by mid-century. Research indicates that an increase of just 1°C in mean annual temperatures can reduce stream flows by as much as 15 percent.