Australian Bushfire Losses: Is the risk increasing? Professor John McAneney

Size: px

Start display at page:

Download "Australian Bushfire Losses: Is the risk increasing? Professor John McAneney"

John Cummings
5 years ago
Views:

1 Australian Bushfire Losses: Is the risk increasing? Professor John McAneney

2 Building Damage 20 th Century (Source: PerilAUS, Risk Frontiers)

3 Insured Losses since 1967 indexed for changes in inflation, population, wealth and building codes 17 bushfire events in ICA List

4 Annual Losses (Source: PerilAUS Risk Frontiers)

5 Summary Statistics Proportion of years with some loss ~ 60% Average number of homes destroyed per year given a loss ~ 170 Average number of homes destroyed per year (taken over all years) ~ 83

6 Time Series Analysis til 2003 The seven day period is introduced here just to define major events The seven day period is introduced here just to identify major fires

7 Population growth (Source: Australian Bureau of Statistics)

8 Why are these statistics so stable? System is climate-driven Most losses occur in mega-events When fires get out of control, not a lot can be done other than get out of the way until they run out of fuel or the weather changes Losses then dependent upon whether firefront intersects populated areas, disposition of houses along bushland edge and human response Big concern for insurers is that such an event were to impinge upon the suburbs of a major city

9 Canberra 18 January 2003 ~ 506 homes destroyed

10 Duffy - Before and After Pre-fire: 25/06/2002 QuickBird Image: 0.6m (PAN), 2.4m (multispectral) Post-fire: 29/01/2003

11 Locations of pre- and post-fire destroyed homes in Duffy Bushland Distance ranges (interval = 100m) superimposed on all pre-fire houses (left) and destroyed houses (right, n=206).

12 Statistics - Percentage of homes destroyed at different distance ranges Distance from adjacent bushland (m) For Ash Wednesday fires, we used data from four affected areas: Fairhaven (71%, n=127); Aireys Inlet (61%, n=98); Macedon (57%, n=97); Mt. Macedon (62%, n=122)

13 Statistics Statistics - Cumulative distribution of destroyed homes in relation to distance from nearby bushland 10 3 Distance (m) o Percentile Otway ranges curve (from Ash Wednesday fires, n=648) and Hobart curve (n=370) reported by Ahern and Chladil (1999).

14 The Urban-Bush Interface

15 Bushfire prone properties how many are there? All major capital cities (N = 8,161,680) 79.7% 6.0% 3.2% 5.0% 6.1% m m m m >700 m

16 Is bushfire a significant risk? Roughly 500,000 homes most at risk: either immediately adjacent to bushland or in the next 100 m At an average loss of 83 homes per year, would take some 7,000 years to destroy this many homes. Annual probability of loss on bushland boundary ~ 1 in 7000 Annual probability of house fire ignition ~ 1 in 1000 Annual probability of death in a motor vehicle accident ~ 1 in 3500

17 Australian Bushfire Potential under GCC Current 2050 Low & High Emissions 2100 Low Emissions 2100 High Emissions Forest Fire Danger Index

18 Global Climate Change Capture background changes in fire risk due to changing air temperature and humidity Fail to capture days of extreme windspeed Since 1967 all large losses have occurred during El Nino or Neutral years Need to understand the impact of GCC on El- Nino-Southern Oscillation system

19 Natural Hazards Risk Ratings Address Information Address: 60 Street: LATHER ROAD NT QLD Suburb name: BELLBOWRIE State: QLD WA SA NSW Postcode: 4070 VIC ACT Elevation: 13 m above mean sea level TAS MOGGILL RD BELLBOWRIE LATHER RD BRISBANE RIVER Brisbane kilometers

21 Conclusions Probability of building losses has remained remarkably stable over last century This is true despite large changes in population, improvements in fire fighting technology and logistics Most losses occur in mega-events Expect this to remain true in future Large event losses will happen again

22 Conclusions Annual probability of destruction of random home on bushland-urban boundary is low on average Little incentive to further reduce individual fire risk on average unless compelled to Attitude that it can t happen to me will often turn out to be true However likelihood of repeat of multi-billion dollar losses is a real possibility that insurers, regulators and government need to take seriously

23 Conclusions 40-50% chance of home survival on the WUI even if undefended this is consistent with the go early or stay policy Risk Frontiers has now categorised every address in Australia by its distance from large areas of bushland and aspect Insurers are beginning to rate homeowners policies on basis of distance from bushland This might encourage better compliance with safety preparations and enforcement of more rational building practices Compliance might also result in reductions in premiums.

An Approach to Pricing Natural Perils

17th An Approach to Pricing Natural Perils Tim Andrews David McNab Ada Lui Finity Consulting Pty Ltd 2010 Why is everyone talking about the weather? The Melbourne and Perth storms were further evidence