SCIENCE

Drought + Spark = Australia Burning

February 10, 2009

I’ve been paying grim attention to the bushfires now ravaging the country outside Melbourne, in the Australian state of Victoria, in part because I have a friend who volunteers with the rural fire service near Sydney. When I visited last year, he played guide during a hike in Ku-ring-gai Chase National Park, where he pointed out fire damage still visible more than a year after the event. (Fire is a natural part of the landscape in many places, including Australia and the western United States. In Australia, for example, many types of Banksia plants rely on bushfire to release seeds from their cones.)

But the current Australian bushfires are especially dangerous. (No one knows how they started, but arson is suspected to be the cause of some.) More than 170 people have died, and more deaths are expected in the coming days. My friend, though, had some insight into what makes these fires so deadly:

Victoria has had a really bad drought for the past couple of years, and temps have been over 40 degrees Celsius (105 degrees Fahrenheit) for almost a week. This makes the trees (gumwoods) nearly explosive, as it dries them to kindling, and evaporates the volatile oils in their leaves. Add to that the strong winds, which are causing spot fires to ignite kilometers ahead of the main fire front. This means that there is almost nothing that can be done to stop an oncoming fire front. The classic approach (backburning) also becomes very dangerous, as you need to burn into the wind, and there is a very good chance of your backburn jumping the break you've created and starting a spot fire behind you. What all of this means is if a fire is headed your way, there's very little you can do to stop it.

If people try to stay in their homes or leave too late, they aren’t able to escape the smoke and flames. “Bad scene all around,” my friend says.

Could climate change be involved? It’s impossible to link a single event to global warming, but the Victoria drought, which began in 1997, apparently fits in with current climate change models, the Guardian reports:

Professor Mark Adams, from the Bushfire Cooperative Research Centre, said the extreme weather conditions that led to the bushfires are likely to occur more often.

"The weather and climatic conditions recently don't augur well for the future. Bushfires are an important and going to be ever-present part of the landscape," he said.