Extreme wildfires are set to surge as the number of days that foster these catastrophic events climbs from 20% to 50% in disaster-prone regions, a new study warns.
David Bowman, a fire ecologist from the University of Tasmania in Australia, and colleagues examined temperature data recorded by instruments onboard NASA’s Aqua and Terra satellites and found population distribution also affected the development of disastrous wildfires.
The work, published in Nature Ecology & Evolution, presents a “real wake-up call”, Bowman says.
“Climate change is about to smash us in the face.”
Extreme wildfires bring destruction to property, economies and, all too often, life. In investigating what influences the development of truly destructive blazes, it’s so far been impossible to tease apart factors such as a region’s natural fire ecology and the flammable legacy of poor land management decisions.
The study compiled a global database of wildfires that burned between 2002 and 2013 to provide fire ecologists and environmental managers important insights into what sets extreme fires apart.
Satellite-mounted instruments, called Moderate Resolution Imaging Spectroradiometers (MODIS), log heat spikes caused by fires and other sources across a global 10×10 kilometre lattice.
Bowman and his colleagues identified more than 23 million of these hotspots and focused on the very hottest. After excluding events such as volcanic eruptions, they were left with 478 bona fide extreme wildfires.
So, what makes a fire go rogue?
Climate and weather conditions are major contributors, Bowman says: “With the exception of tropical deforestation fires, they’re all related to anomalous weather conditions.”
These include higher than usual temperatures, winds and drought, as well as excess rainfall in usually arid regions that causes fuel build-up for the following season.
Almost a third of the studied fires – 144 – were classified as disastrous, meaning they resulted in loss of life or property, or elicited an emergency response from the government.
But unlike other extreme fire events, which occurred worldwide, disastrous events were more common in specific regions – notably south-east Australia and western US and Canada, where urban sprawl brings people close to forested areas.
Population distribution isn’t the only factor. Landscape management is also important, Bowman says. The heavily managed Mediterranean landscape, for instance, is less disaster-prone than the bushlands of Australia and the western US, which have been largely left to grow unimpeded since Indigenous burning practices stopped a century or more ago.
Climate was identified as a factor in a whopping 96% of these disastrous fires and is likely to become increasingly significant over time.
“Climate change projections suggest an increase in days conducive to extreme wildfire events by 20 to 50% in these disaster-prone landscapes, with sharper increases in the subtropical Southern Hemisphere and European Mediterranean Basin,” the report concludes.