Australia’s bush – hot, dry and flammable

Southern Australia started 2015 hot; very hot. The maximum temperature, as officially recorded in Adelaide on January 2, was 44.1 degrees Celsius. On the same day, 40.5C was recorded at Melbourne Airport.

The summer months in Australia always bring the danger of bushfires. Often started by lightning, these fires spread rapidly in the usually tinder-dry bush; woodland or forest usually containing gum trees.

The gum tree, otherwise known as the eucalyptus, is ubiquitous in Australia and produces the antiseptic oil which, unfortunately, is explosively flammable. In fact, the tree produces compounds which are so volatile that a haze often hangs above eucalyptus forests.

The Australian Blue Mountains take their name from this haze, which sounds nice and romantic, but that same haze often carries a fire rapidly through the forest canopy.

This year’s fire season is at its peak in South Australia, as authorities warned that the state faced its worst wildfire danger since the deadly 1983 blazes. Bushfires have forced the residents of 19 Adelaide Hills towns to seek shelter. Officials said the scenic Adelaide Hills, northeast of Adelaide city, faced “an incredibly dangerous fire” which was impossible to fight head-on.

Dotted with pretty villages, the area is known for its farming produce and wineries and has a population of some 40,000. The blaze at Sampson Flat is burning freely in all directions and in an erratic manner, and now covers 4,741 hectares.

South Australia’s Country Fire Service chief Greg Nettleton said: “Right at this moment, residents in the Adelaide Hills are being confronted by a fire which hasn’t been seen in the hills since the 1983 bushfires of Ash Wednesday,”

In Victoria, one fire is still burning out of control near Maroona in the state’s west after firefighters battled more than 320 blazes overnight. In February 2009, the devastating “Black Saturday” bushfires in Victoria left 173 people dead and razed more than 2,000 homes, in the nation’s worst natural disaster of modern times.

Temperatures should drop by around 10 degrees Celsius on Sunday as a trough of showers passes over, but this alone won’t make any difference to a burning fire. What might help is any change in prevailing breeze that could turn a fire back on itself and so deprive it of fuel.