Climate change is lengthening fire danger seasons around the world, although the picture is not so clear for Australia, according to a new study.
On first glance the findings suggest the continent that is so famous for bushfires bucks the global trend, but the researchers warn this may not be the case.
They say the anomaly in the study’s findings is due to Australia’s highly variable climate.
“We’re not seeing [the global trend] clearly in Australia because of a statistical problem, not because it isn’t there,” says Dr David Bowman, a professor of environmental change biology at the University of Tasmania.
“The nightmare is that by the time those signals are really clear, you won’t be needing to do the statistical analysis. Everybody would have already got the message.”
Climate strongly influences the development of wildfires, says Bowman. For example, if it is dry, hot and windy, it will be easier for a fire to start than if it is wet, cool and still.
The severity of such ‘fire weather’ conditions is commonly communicated publicly via fire danger index boards — for example a total fire ban day is when fire weather conditions will encourage fires to burn out of control.
Periods in the year when the fire index is persistently high are called ‘fire weather seasons’.
In a study published today in Nature Communications, Bowman and colleagues used global data to develop a fire danger index that could be used to detect trends in fire weather seasons throughout the globe from 1979 to 2013.
“Since 1979 we see a small but significant lengthening of fire seasons,” says Bowman.
The researchers found that over 53.4 per cent of the Earth’s vegetated surface, there had been an increase in frequency of long fire weather seasons.
And they found that over 25.3 per cent of the surface, fire seasons had lengthened by 18.7 per cent.
Previous research had found that some regions of the world, such as the US, are increasing their fire weather season length, but this is the first study to show this trend applies at a global scale.
“Nobody had ever done a global analysis to find a lengthening of fire seasons affecting a very large part of the surface of the planet,” says Bowman.
Press link for more: Anna Salleh | abc.net.au