Climate change is causing bigger fires

Posted bybetterfuturePosted inIn the news, NewsTags:, , , , , ,

A major CSIRO study has found that forest fires in Australia have been getting bigger, and the main reason is human-caused climate change.

CSIRO is Australia’s premier government research agency. The paper titled “Multi-decadal increase of forest burned area in Australia is linked to climate change“ was published in the scientific journal Nature Communications. CSIRO published their own news release, and the story was widely covered in the media (eg. 1 2 3)

The team of 8 researchers used satellite and ground-based information on forest area burned, coupled with climate and weather data and simulated fuel loads, over the past 90 years. They found an overall linear increase in total area burned per annum but an exponential increase during autumn and winter.

CSIRO also found forest areas are being burned more often. Most disturbingly, the frequency of ‘megafire years’ (when more than a million hectares burnt, has “markedly increased since 2000“. Comparing 1988-2001 to 2002-2019, the area burned per year has increased by 800%.

In relation to climate change, the paper says: “Australia’s mean temperature has increased by 1.4 °C since 1910 with a rapid increase in extreme heat events, while rainfall has declined in the southern and eastern regions of the continent.” This has specific implications for bushfires:

“The increase in forest burned area is consistent with increasingly more dangerous fire weather conditions, increased risk factors associated with pyroconvection, including fire-generated thunderstorms, and increased ignitions from dry lightning, all associated to varying degrees with anthropogenic climate change.”

Interestingly, the researchers also considered the Continuous Haines index (C-Haines, a measure of atmospheric instability) to “indicate a high chance of extreme wildfires such as those with thunderstorm formation in fire plumes“. These conditions are associated with extreme and dangerous fire behaviour and occurred to an unprecedented extent in the 2019-2020 season.

The role of prescribed burning was also analysed:

“We found no changes in the mean annual area of prescribed burning over the past 32 years, although we have no information on how successful those burns were in reducing fuel loads. However, given the lack of trend and the fact that on average, only 1% of forests are subject to fuel reduction burns every year, it is very likely that fuel management had no effect on the observed multi-decadal increasing trend in the burned area of forest fires. We also note that the main objective of fuel management is to reduce fire risk and severity, which might or might not result in reduced total burned area.”

Grimly, the researchers find that the trend of bigger and more frequent forest fires is likely to get worse under future projected climate change.

IBG comment

  • This study confirms what many other researchers and experts have been saying, that fires are getting worse and will get worse still if climate change is not brought under control.
  • It also confirms that we need to adapt our fire management methods to these more challenging conditions. Adaptation to our worsening fire climate is a priority for IBG advocacy. We have argued for a suite of improvements to reduce bushfire impacts on communities, firefighters and the environment.
  • Critical measures include rapid suppression of fires, improved firefighting strategies and building more resilience into at-risk communities. More effective analysis and review of past fires is fundamental to ongoing improvement.
  • IBG analysis and suggestions are detailed in our comprehensive submission to the NSW Independent Bushfire Inquiry.

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