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Climate Change Impacts:
Agriculture
Southern Ontario's relatively mild climate supports a productive agricultural sector generating more than $7 billion annually from soybeans, corn, and wheat, as well as fruit and livestock. There are likely to be some positive impacts for agriculture resulting from a warmer climate, although current evidence suggests that the negative consequences could outweigh the positive. In general, however, regional development, technological advances, and market fluctuations have as much influence on farmers as the climate.

Changes in temperature, precipitation cycles and severe weather will have many effects upon farming. Among the potential impacts of climate change with implications for agriculture in Ontario are:

• A Shift in Optimal Weather Conditions
  Overall, optimal weather conditions are expected to shift northward and eastward in the Great Lakes region. Ontario may benefit from warmer temperatures and a longer growning season, but may be constrained by thin and acidic soils.
  
  
• Changes in Crop Yield
  Increased atmospheric carbon dioxide and nitrogen, as well as a longer growing season, could boost yields of some crops—such as soybeans and corn. However, higher ozone concentrations can damage soybeans and horticultural crops, countering positive impacts of a warmer climate. In addition, severe storms and floods during the planting and harvest seasons could decrease crop productivity. Hotter and drier summers and potentially more droughts would hurt crops and may require irrigation of previously rain-fed crops, increasing the costs for farmers as well as increasing pressures on water resources.
  
  
• More Favorable Conditions for Some Pests
  Warmer winters with longer freeze-free periods, shifts in rainfall, and extended growing seasons may create more favorable conditions for pests. More southerly pests, such as corn earworms, may expand northward. Such a shift already appears to be happening with bean leaf beetles, which feed on soybeans and serve as vectors for a virus that causes disease in soybeans. Warming will increase the rate of insect development and the number of generations that can be completed each year, contributing to a build-up of pest populations. Increased pests may drive farmers to use more pesticides or related chemicals, placing an additional burden on water quality.
  
  
• An Increase in Risk for Perennial Crops
  Further climate variability is particularly problematic for perennial crops, such as fruit trees, because adjustments cannot be made as flexibly and long-term investments in the crops and specialized equipment are at risk.
  
  
• A Decrease in Livestock Productivity
  High temperatures suppress appetite and decrease weight gain in livestock, while warmer winters and less snow cover are projected to reduce the quantity and quality of spring forage, overall decreasing milk quality. In addition, any extreme weather events, such as heat waves, droughts, and blizzards, have severe effects on livestock health, although intensively managed livestock operations are better able to buffer the effects of extreme events.