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Despite the widely held belief that the arrival of aboriginal people in Australia caused an increase in fire activity, a comprehensive study of 223 sites by an international team of scientists suggests that they did not have a significant impact on the fire regimes.
According to Dr Scott Mooney from the University of New South Wales, who led the team, the colonisation of Australia 50,000 years ago does not correlate with any changes in fire activity, despite the statements of prior studies. “One of the problems with previous studies is that they have used supposedly ‘iconic’ sites, like Lynch’s Crater, and these have been interpreted as showing an increase in fire activity after Aboriginal settlement.”
Instead, the scientists believe that the fire records (suggest that fire activity in Australia reflects changes in climate, such as glacial and interglacial periods. The records show higher fire activity between 70,000 to about 28,000 years ago, followed by a decrease during the glacial period (until 18,000 years ago), then increasing as the climate warmed.
This pattern is consistent with fire activity and climate trends worldwide. Dr Mooney says “There are lots of linkages between climate and fire, for example via ignition (lightning) and indirectly through vegetation- fuel loads, flammability, etc. The study found that there is greater fire activity during warmer climates and less fire activity when climate is colder.”
According to the records, the arrival of Europeans on the Australian continent in 1788 seems to have caused a substantial increase in fire activity. Dr Mooney says “the increase of the last few hundred years is thus a little hard to attribute solely to European settlers and might be (due to) increased CO2 or global warming signal?”
“Nonetheless, when I look at all the sites I have studied the European period always has more charcoal in it than preceding periods.”
