Australian Bushfire Losses: Past, Present and Future

This study reviews and extends previous analyses of the bushfire risk to the built environment in Australia. The most salient result is that the annual probability of building destruction has remained almost constant over the last century despite obvious demographic and social changes as well as improvements in fire fighting technique and resources. Most historical losses have taken place in extreme fires with an average return period of a decade or two and which when repeated are likely to overwhelm even the most professional of fire services. Because of these observations and despite predictions of an increasing likelihood of conditions favouring bushfires under global climate change, we suspect that building losses are unlikely to alter dramatically in the near future. By evenly spreading the risk over the entire bushland-urban interface, we calculate the annual chance of a random home being threatened by a bushfire to be of the order of 1 in 3000, a factor of three lower than the ignition probability of a structual house fire. The probability of destruction is lower still at around 1 in 5000. Thus the incentive for individuals to mitigate and reduce the bushfire danger even further is low. In particular, without strong political leadership and regulatory pressure preventing development adjacent to bushland, the prospects for further significant loss events, such as the Ash Wednesday fires, in which 2300 homes were destroyed and 75 people lost their lives, will remain unchanged