Australia鈥檚 recent wildfires burned an area of forest unprecedented anywhere in the world, according to the most authoritative analysis yet of the devastation. The blazes were also found to be so extreme that climate change models were unable to replicate the events.
By early January, the bush fires had burned around 5.8 million hectares of forest in the states of New South Wales and Victoria. Australia recorded its biggest ever forest fire, a blaze that burned more than half a million hectares near Sydney from October until mid-January.
Matthias Boer at Western Sydney University and an international team found that the extreme fires burned around 21 per cent of the forest biome in eastern Australia between September 2019 and 13 January 2020.
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Over the past two decades, losses to fire in this region usually amounted to less than 2 per cent each year, says Boer. The losses also eclipsed the proportion burned in听any other continental forest biome in the world over the same period, most of which were well below 5 per cent annually.
鈥淭his percentage of burning in forests is unprecedented nationally and globally,鈥� says Boer. 鈥�There has been a lot of talk in social media about the unprecedentedness of the fires, but this was not substantiated in the peer-reviewed literature by anyone before.鈥� His team analysed of seven forest biomes across the world and computed the percentage burned in the continental sections of those forests.
A fifth of east Australia鈥檚 forest being burned is likely to be an underestimate, as the analysis doesn鈥檛 cover the entire fire season or include Tasmania, which was hit by blazes after the analysis鈥檚 cut-off date.
Even though most of these forests are dominated by eucalyptus trees, which are excellent at surviving fire, the burning of such a large proportion of the forest isn鈥檛 sustainable, says Boer. Animals also face 鈥渟ignificant consequences鈥�, he adds, because the huge areas burned may increase the distance to food sources.
A separate study also demonstrated how extraordinary the fires have been. Researchers found that climate change models were unable to replicate the intensity of the New South Wales blazes now or even in a much warmer future.
The result isn鈥檛 a sign the models are bad, but that modelling fires is complex, says Benjamin Sanderson at the European Center in Research and Advanced Training on Scientific Computing in France. So many factors interact with one another, from climate and weather to soil and hydrogeology, as well as how people manage forests. As such, he says it will be hard to quantify the role human-caused climate change played in the bush fires, as .
鈥淭he fact that we aren鈥檛 seeing events like this in the projections is an indication that we are not completely exploring the space of possible future [climate change] impacts,鈥� he says.
A third study, led by Andrew King at the University of Melbourne, found the extreme drought that created the conditions for the mega fires was largely a result of two climate phenomena, La Ni帽a and the Indian Ocean Dipole. The two led to exceptionally low rainfall in Australia.
Australia is still in fire season, but authorities , and firefighters in Victoria they had largely extinguished a fire that had raged for three months.
Journal references: Nature, DOIs: , and
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