1. December 2002 Section 6b Canadian Impacts of Climate Change (2)

2. CGCM1 results suggest very hot days across Canada will become much hotter…

3. …extreme cold days will become much less cold

4. Change in Cooling Degree Days (2090) …and space cooling demands will rise dramatically

5. Number of hot days above 30  C Heat waves in Canadian cities are expected become more frequent

6. By 2080, Toronto could experience more than 30 “Hot Days” in excess of 32  C each year Toronto

7. Increased heat stress and related degradation in air quality will have major health effects Air quality

8. There are also risks of the spread of diseases West Nile Virus Lyme Disease

9. Normally defined on basis of statistical frequency –e.g. 2 SD, 3 SD, upper/lower decile or percentile, return period –Can apply to intensity, duration, areal extent and/or frequency –can also often be considered as weather that is out-of-place By definition, these events rarely occur –Infrequency makes probabilities hard to estimate An extreme becomes a disaster when it causes large ecological or socio-economic damages –Human factors are important –Greatest disasters often linked to 2 or more unusual weather features occurring at same place/time Defining extreme events and related disasters

10. In some ways, the risks of extreme events are like the odds in games of chance Game of Chance AnalogyProbability 1 in 6 1 in 36 1 in 216 1 in 1296

11. Extreme events can cause many types of disasters Lightning damage Flood losses Ecological disaster Structural damage Wind damage Loss of life

12. Factors involved in two recent Canadian disasters The 1997 Red River Flood wet fall in 1996 unusually high snow accumulation in headwaters during winter major April snow storm in Manitoba moderate rate of melt large, moderately populated area The 1998 Ice Storm Warm, moist air mass related to El Nino event unusual atmospheric blocking/duration of event related to NAO cold air in valley followed by cold weather large, heavily populated area

13. Climate change and natural variations in climate can change the risks of extreme events 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 Climate change may change the behaviour of NAO and ENSO Climate change can also directly cause large changes in weather behaviour and hence in probability of extremes –Much like playing with loaded dice

14. More frequent intense rainfalls increases the risks of local floods

15. Total expenditures for 1982-99 Federal: $8.3 billion Other: $20 billion Weather related disasters alone cost Canadians more than an average $1 billion per year

16. Analyses suggest increases have occurred in some types of weather extremes in some, but not all areas Individual extreme events occur rarely and hence are difficult to link directly to specific “causes” However, many of the events are broadly consistent with climate change projections Hence these events are good examples of what may happen more often in the future Are recent weather extremes due to natural variability or to climate change?

17. Climate change will also increase the risks of forest fires across much of Canada Canadian Forest Service

18. …and extend the duration of the annual fire season

19. Canada’s coastal fisheries will be affected by changes in species distribution

20. Ecological preserves within the national parks may be at risk