Projections for Extreme Weather



Extreme Weather – costs, probability, from ice storms to forest fires, droughts, and floods!

See also temperatures and precipitation in Section 6.2.1b

Source: Science and Impacts of Climate Change CD -Presentation Graphics (2002) MSC Environment Canada/ ESS Natural Resources Canada, December

Weather related disasters alone cost Canadians more than an average $1 billion per year.

The extremes of weather conditions shown in the following scenarios indicate the level of vulnerability to these impacts, as they affect both the natural and built communities. The number of disasters and the damages for these disasters are discussed in Section 6.2.2.e Insurance.

These projected impacts and their consequences are good news/bad news for our communities. Shorter winters will likely mean lower maintenance and snow-removal costs, a shorter winter recreation season, and a longer summer recreation season. More frequent freezing rain events could affect power lines and road and airline safety. More frequent freeze-thaw cycles could speed up the weathering process on buildings and roadways. Ice roads, traditionally used to transport large cargoes of supplies to villages and towns in the north, will have a shorter life span.

We do know that climate change could make the first factor, an intense El Nino, occur more frequently. Climate change and natural variations in climate can change the risks of extreme events.

Source: Science and Impacts of Climate Change CD -Presentation Graphics (2002) MSC Environment Canada/ ESS Natural Resources Canada, December

Try this your self! See a math teacher!!

Changes in NAO and ENSO patterns with time can change the probability of unusual weather. The intense El Nino and unusual NAO behaviour in 1997-98 were important factor in the 1998 ice storm. NAO refers to North Atlantic Oscillation, while ENSO means El Nino-Southern Oscillation.

The factors involved in a recent Canadian disaster, the 1998 Ice Storm, were:

  • warm, moist air mass related to El Nino event
  • an unusual atmospheric blocking/duration of event related to NAO
  • cold air in valley
  • followed by cold weather in a large, heavily populated area

Knowing the conditions which caused this ice storm allow predictions or risk assessment for the return of these conditions, the occurance of the next ice storm in a study area.

See the map below of the south-central Ontario area showing the probability of the next ice storm in that region.

Source: Don MacIver, Science Assessment, Environment Canada

1. What do the green and beige areas represent? Locate Shelburne on a map showing elevation.
2. Explain what the 30 isoline means.

ACTIVITY 3 Research
What conditions would explain the heavier ice during the 1998 storm further east in Ontario?

Some records may help put this into an Ontario perspective. The costs of the past extreme weather events like the ice storm will influence the costs of insurance in these areas. See also Sections 6.2.2.d and 7.1.1e Insurance.

To put the costs of extreme weather events in a Canadian perspective, see the map below.

Source: Science and Impacts of Climate Change CD -Presentation Graphics (2002) MSC Environment Canada/ ESS Natural Resources Canada, December

1. The numbers shown on the weather map above end at 1999. What is the total in $billion for this period?
2. What sectors are represented in “others”?
3. Find the most recent data to update the cost to 2005.

ACTIVITY 5 Research
1. Find the data and plot a bar graph showing each year’s totals ($billion) from 1982 to 2004.
2. Draw a line on the bar graph in #1 to show a projection of the federal and other costs for future extreme events up to and including 2014.

ACTIVITY 6 Questions
1. List the y-axis and the range used in these graphs. Which years of data are used as benchmarks for running the projections?
2. What is the common pattern seen in most graphs? What is the major exception?
3. Describe the phenomena represented by this group of graphs.

Climate change will also increase the risks of forest fires across much of Canada.

This estimate of how forest fires in Ontario will respond to climate change by month does not take other factors of possible change into account.

The forest fire season in Ontario is expected to begin much earlier.

By May there is already significant risk of fire.

Source: Stocks, B.J.; Fosberg, M.A.; Lynham, T.J.; Mearms, L.; Wotton, B.M.; Yang, Q.; Jin, J-Z.; Lawrence, K.; Hartley, G.R.; Mason, J.A.; McKenney, D.W. 1998. “Climate change and forest fire potential in Russian and Canadian boreal forests”. Climatic Change 38:1-13.

Human health in our cities, especially those with higher heat island effect, will be at greater risk.

Source: Science and Impacts of Climate Change CD -Presentation Graphics (2002)

MSC Environment Canada/ ESS Natural Resources Canada, December


1. What color is used for the base-line data, that is the observed data?
2. Why is 30 degrees Celsius  used in this graph?
3. Plot Toronto or London on a separate bar graph. Plot time on the x axis with ay axis of temperature in oC. Put the years in order from left to right.

ACTIVITY 8 Research
Draw a curve to project the top of each line to 2100. If one generation equals 20 years, how many generations of your family are represented on this total graph?

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