In Ontario, average annual air temperature could be 3°C to 8°C higher by the latter part of the twenty-first century, leading to fewer weeks of snow, a longer growing season, less moisture in the soil, and an increase in the frequency and severity of droughts.

Global climate models suggest that over the next 50 years, southern Ontario is likely to experience more frequent, more intense, and longer heat waves. An increase in the number of hot days (higher than 35°C) could increase the risk of heat-stress-related health problems, especially in the very old, the very young, and those with chronic lung diseases such as asthma.

Warmer temperatures and earlier and longer frost-free periods (longer by as much as five weeks) will extend the grazing season and increase the potential yield of heat-loving crops, such as corn, soybeans, and tomatoes.

The level of the Great Lakes may be reduced by up to one metre from present levels by 2050. Levels this low could have negative impacts on shipping, fisheries, water quality, water intake infrastructure, and shoreline property.In Ontario, average annual air temperature could be 3°C to 8°C higher by the latter part of the twenty-first century, leading to fewer weeks of snow, a longer growing season, less moisture in the soil, and an increase in the frequency and severity of droughts.

Potential regional impacts

• There will be likely increases in the frequency and severity of forest fires.
• Water levels in the Great Lakes could decline by more than 1  m by 2050, disrupting navigation routes and reducing shipping capacity.
• A decrease in rainfall will mean that farmers would need more irrigation in southwestern Ontario, particularly in drought-prone soils and for shallow-rooted crops such as potatoes.
• Cold-water fish species, such as lake trout and lake whitefish, may disappear from southern Ontario as their habitat changes.
• The warmer weather will encourage white-tailed deer to flourish, whereas experts expect that the distribution of moose, easily stressed by heat, will shift northward.
• More frequent freezing rain events could affect energy transmission and road and airline safety.
• A warmer climate may permit the spread of new diseases from warmer climates, such as Lyme disease, malaria, and West Nile virus.

Curriculum linkages

Biology: The sustainability of ecosystems (academic)

• (Relating science to technology, society, and the environment) Assess the impact of technological change and natural change on an ecosystem.
• Identify and evaluate Canadian initiatives in protecting Canada's ecosystems.

Earth and space science: Weather dynamics (academic)

• (Relating science to technology, society, and the environment) Explain the role of weather dynamics in environmental phenomena and consider the consequences to humans of changes in weather.

Biology: Ecosystems and human activity (applied)

• (Developing skills of inquiry and communication) Select and integrate information from various sources, including electronic, print, and community resources, to answer the questions.
• Analyze the data and information gathered to clarify aspects of the concern or issue.
• Communicate the results of the investigation using a variety of oral, written, and graphic formats.
• (Relating science to technology, society, and the environment)

Earth and space science: Weather systems (applied)

(Relating science to technology, society, and the environment) Identify the impact of climate change on economic, social, and environmental conditions.