The effects of climate warming on streamflow are not known with certainty. Precipitation is expected to increase and this could lead to an increase in streamflow. This however may be balanced by an increase in evaporation. Spring melt will occur earlier and last longer, causing changes in the timing and amount of spring runoff. As permafrost thaws, sub-surface water storage capacity may increase and surface runoff will decrease. The frequency of flooding may also increase. Glaciers at lower elevations may begin to retreat and this may temporarily increase flow in streams. This source of water however will gradually decrease over time.

(Source: Government of Yukon)

In the Old Crow Flats region of the Yukon, the local population suspects that water levels in thaw lakes are dropping. They fear that a trend towards warmer temperatures and earlier springs will ultimately dry up the wetlands and threaten fishing, hunting and trapping. The lake shown in black on the 1990 satellite image is drying up and contained almost no water in 1994 (shown by decrease in black area on image).

(Source: C. Duguay, Université Laval)

Water temperatures will increase as climate warms. Some freshwater fish species may increase due to greater productivity in warmer waters. However, cold water species, such as Arctic Char, may not be able to adapt. These species would face greater competition for food as southern species move northward.

In winter, northern communities rely on ice roads which cross lakes and rivers for transportation. As climate warms, the period of time over which these roads will be in operation will decrease. The Mackenzie River barge season could increase by as much as 40% in response to warmer temperatures. Lower water levels however, would make navigation more difficult.

Credits

Brooks, G.R., 2000. Streamflow in the Mackenzie valley; in The physical environment of the Mackenzie Valley, Northwest Territories: a baseline for the assessment of environmental change, L.D. Dyke and G.R. Brooks (ed.);Geological Survey of Canada, Bulletin 547, 212 p.

Brugman, M.M., Raistrick, P. and Pietroniro, A. 1997. Glacier related impacts of doubling atmospheric carbon dioxide concentrations on British Columbia and Yukon; Chapter 6 in Responding to global climate change in British Columbia and Yukon, Volume I of the Canada Country Study: Climate Impacts and Adaptation, E. Taylor and B. Taylor (ed.); Environment Canada and BC Ministry of Environment Lands and Parks, 350 p.

Duguay, C., Université Laval, pers. comm. Maxwell, B., 1997. Responding to global climate change in Canada's Arctic; Volume II of the Canada Country Study: Climate Impacts and Adaptation, Environmental Adaptation Research Group, Atmospheric Environment Service, Environment Canada, 82 p.