More than 250,000 lakes (including the Great Lakes) encompass 181,153 km2 or about 17% of the province. These lakes are critical to the long-term health of Ontario’s ecosystems and to the people who depend on them. The Great Lakes provide water for over 40 million people in Canada and the United States, support a significant shipping industry and a vital commercial and sport fishing industry.
Only about 1% of the lakes are renewed each year by snowmelt and rain. Managing the lakes sustainably in a rapidly changing climate will be very important and challenging. Climate change could affect both the quantity and the quality of water in Ontario.
Impacts of Climate Change on Lakes and Rivers
Global warming is causing climate change which is characterized by:
- higher water temperatures
- changes in rain and snowfall patterns
- a significant reduction in glacial ice and snow cover
- changes to atmosphere and ocean circulation patterns and
- higher air temperatures
Climate change is impacting the Earth’s water balance and could affect the availability of water for human use. Climate change could also mean the potential for more extreme weather events and water-related hazards, such as flooding, drought and poorer water quality.
For Ontarians, lower water levels could mean:
- less available water supplies for domestic, agricultural, commercial and industrial uses
- increased demand for diversions and bulk water transfers (internationally, nationally and
provincially) - increased conflict between water users
- less capacity to generate hydroelectric power at peak use times
- decreased access to waterways, altering shipping operations and navigational routes
- altered flow rates at water control structures (dams etc.) and
- decreases in water quality (more micro-organisms)
Higher water levels as a result of climate change could mean:
- increased risk of flooding (more public safety hazards)
- increased erosion and shoreline damages
- increased infrastructure failures (roads, bridges, etc.) and
- decreased water quality (due to increased runoff and debris)
Impacts of Climate Change on Fish and Aquatic Life
Ontario’s rivers and lakes support many economically, recreationally, and socially important kinds of fish and other aquatic life. Changes in water quality and quantity due to climate change could have major impacts on these fish and the aquatic communities in which they live.
In most aquatic organisms, growth and reproduction are strongly influenced by water temperatures. Fish, for example, can be separated into those that do best in cold, cool, and warm waters.
Typical members of these groups include:
- Cold water fish: lake trout, Chinook salmon, whitefish, sturgeon
- Cool water fish: walleye, yellow perch, muskellunge
- Warm water fish: largemouth bass, carp, bluegill
Climate change-driven increases in water temperatures could make some rivers and lakes unsuitable for the fish that now live there. For instance, higher lake temperatures could result in shifts from cold water species such as lake trout, to cool and warm water species like yellow perch and largemouth bass. As a result, the distributions and population sizes of some fish species may undergo dramatic changes as they are replaced by more temperature tolerant species. In some cases, already threatened or endangered species such as sturgeon may disappear completely.
The impacts of climate change would be felt throughout the food web. For example, expected changes in the composition and availability of phytoplankton and zooplankton – the primary foods at the bottom of the food web – may favour some species over others. The end result could be a reshuffling of the organisms making up aquatic communities in many of Ontario’s rivers and streams. These types of changes may, in turn, make conditions more favourable for invading species like zebra mussels and the round goby and for fish diseases such as Viral Hemorrhagic Septicemia (VHS).
Ontario’s Lifeblood
Water is the ‘lifeblood’ of Ontario’s ecosystems, and managing its variability in both quantity and quality is critical to ensuring the continued growth and success of Ontario’s society and economy. A shortening of the snow and ice season would also affect social, economic and tourism aspects of the province, such as the winter recreational activities of skiing, snowmobiling and ice fishing.
Water managers within the Ministry are working to maintain sustainable water supplies and manage natural hazards, while safe-guarding provincial interests in boundary waters areas, in the face of the impacts of climate change.
The following reports and publications provide more detailed information about climate change and lakes and rivers. Contact Applied Research and Development Branch for information on how to obtain these reports:
- Croley, II T.E. 1992. CCC GCM 2xCO2 Hydrological impacts on the Great lakes. In Climate, Climate Change, Water level forecasting and frequency analysis. Supporting Documents Vol. 1 water supply scenarios. Task Group 2, Working Committee 3, IJC. Levels Reference Study, Phase II. Environment Canada. 2004. Threats to Water Availability in Canada. National Water Research Institute, Burlington, ON. NWRI Scientific Assessment Report Series N0. 3 and ACSD Science Assessment Series
No. 1.
- Environment Canada. 2004. Threats to Water Availability in Canada. National Water Research Institute, Burlington, ON. NWRI Scientific Assessment Report Series N0. 3 and ACSD Science Assessment Series
No. 1.
- Hengeveld, H., Whitewood, B., and Fergusson, A. (Environment Canada). 2005. An Introduction to Climate Change: A Canadian Perspective. Government of Public Works and Government Services. IPCC. 2001a. Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, U.K.IPCC. 2007. Climate Change 2007: The Physical Science Basis: Summary for Policymakers. A Contribution of Working Group I to the Fourth Assessment Report of the IPCC, Intergovernmental Panel on Climate Change, Geneva, Switzerland. 21 p.
- IPCC. 2001a. Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, U.K.
- IPCC. 2007. Climate Change 2007: The Physical Science Basis: Summary for Policymakers. A Contribution of Working Group I to the Fourth Assessment Report of the IPCC, Intergovernmental Panel on Climate Change, Geneva, Switzerland. 21 p.
- Kling, G. W., Hayhoe, K., Johnson, L.B., Magnuson, J.J, Polasky, S., Robinson, S.K., Shuter, B.J., Wander, M.M., Wuebbles, D. J., Zak, D.R., Lindroth, R.L., Moser, S.C. and Wilson, M.L. 2003. Confronting Climate Change in the Great Lakes Region: Impacts on Communities and Ecosystems. Union of Concerned Scientists: Cambridge, Massachusetts, and the Ecological Society of Americas, Washington, D.C. USA.
- Lofgren, B. M., Quinn, F.H., Clites, A.H., Assel, R.A., Eberhardt, A.J., and Luukkonen, C.L. 2002. Evaluation of potential impacts on Great Lakes water resources based on climate scenarios of two GCMs. Journal of Great Lakes Research 28: 537-554.
- LOSLR, International Lake Ontario-St. Lawrence River Study Board. 2006. Options for managing Lake Ontario and St. Lawrence River water levels and flows. Final Report for the International Joint Commission.
- Mortsch, L., Alden, M., and Scheraga, J. 2003. Climate change and water quality in the Great Lakes region-risks, opportunities and responses. In: Climate Change and Water Quality in the Great Lakes Basin, Michigan - Great Lakes Quality Board, International Joint Commission.
- Mortsch, L., Alden, M. and Klaassen, J. 2005. Development of climate change Scenarios for Impact and Adaptation Studies in the Great Lakes-St. Lawrence Basin. Report prepared for the International Joint Commission, International Lake Ontario- St. Lawrence River Study board. Hydrologic and Hydraulic Modeling Technical Working Group, 21pp., Downsview ON.
- Schindler, D. W. 2001. The cumulative effects of climatic warming and other human stresses on Canadian freshwaters in the new millennium. Canadian Journal of Fisheries and Aquatic Science 58: 18-29.
- Schindler, D.W., Bayley, S.E., Parker, B.R., Beaty, K.G., Cruikshank, D.R., Fee, E.J., Schindler, E.U.,and Stainton, M.P. 1996a. The effects of climate warming on the properties of boreal lakes and streams at the Experimental Lakes Area, northwestern Ontario. Limnology and Oceanography 41: 1004-1017.
Photo Credit: Agawa Canyon - Scott Finucan
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