Bushfires are a major economic, social and environmental hazard in Australia. Climatic and weather conditions have a significant impact on the incidence of bushfire. Dry grass, parched shrubs, dead leaves and twigs are the basic fuel of bushfires. Drought, high temperatures and low humidity dry out timber and grass making it more flammable. High winds supply more oxygen to flames and increase their intensity. Wind also carries burning embers which start new fires. Fire ignition by lightning is also important, and regrettably, the activity of arsonists is increasing.
Of most concern to fire fighters are days classified as having “very high” or “extreme” fire dangers. On very high fire danger days fires start and spread quickly and are very intense.
The extreme fire danger rating indicates that fires become uncontrollable very quickly and are all but impossible to put out until weather conditions change. Fire danger will be exacerbated by climate change as the climatic conditions conducive to fire are expected to increase over much of Australia. For example, more frequent and intense droughts and heat waves are projected.
Projections also indicate an increase in the intensity and frequency of bushfires. The 2010-11 WA bushfire season was one of the most devastating and destructive in the state’s history. The bushfires in the Perth Hills in February 2011 destroyed 71 homes with a further 39 homes and other structures being damaged. Then the two-day blaze that occurred in November that same year near Margaret River, tore through about 4500 hectares of bushland, including the coastal community at Prevelly beach.
Header image by Wendy Slee.