Climate change is increasing the frequency of mega-fires in Australia and endangering entire ecosystems, new research from CSIRO has found.
- The frequency of mega-fires, in which over 1 million hectares of forests were burned, increased suddenly after 2000
- The worst fire seasons typically follow a La Niña weather phenomenon that Australia is currently experiencing
- The amount of prescribed incineration has not changed over the last three decades
Over the past three decades, Australian forests have undergone an 800 per cent increase in the extent of the area’s burnt bush fires, with scientists warning that ecosystems are at risk because they are unable to recover between devastating infernos.
The research, published in the journal Nature Communications, is based on a first-of-its-kind study that used 32 years of satellite data and 90 years of terrestrial data sets from climate and weather observations.
The increase in burned areas has not been limited to the summer months. Since 1988, the fire season has been extended to the cooler months with a more than fivefold increase in the annual average burned area in winter and a tripling in autumn.
“All of these things have changed completely over the last 15 years, with basic fires spreading throughout 12 months,” said CSIRO’s chief researcher Dr. Pep Canadell.
Dr. Canadell said the study combined analysis of previous forest fire sites with eight causes of fire activity, including climate, fuel accumulation, ignition and prescribed burning.
“While all eight drivers of fire activity played different roles in affecting forest fires, the climate was the overwhelming factor driving fire activity,” he said.
Risk reduction is not a factor
Since the Black Summer bush fires, there has been fierce debate about the role of risk-reducing burns in the severity of the fires, but Dr. Canadell says the prescribed burning has not actually changed.
“Overall, the prescribed burning has really not changed at all, and perhaps most importantly, just to realize that we burn one percent a year of the forests, which is a really small amount,” he said.
CSIRO scientist Mick Meyer agreed, saying the prescribed burning was mostly done to protect assets.
“If you tried to burn the whole country off, you would change the ecosystems in reality,” he said.
Do not be fooled by La Niña
Dr. Canadell also warns that despite an exposure to wet conditions this year due to a La Niña, the year after such a weather phenomenon typically brings a bad fire season.
“The highest area of combustion actually comes right after a La Niña year, because the wetness across the continent really brings up the fuel loads,” he said.