Climate change significantly alters future wildfire mitigation opportunities in southeastern Australia.

Prescribed burning is used globally to mitigate the risks of wildfires, with severe wildfires increasing in frequency in recent decades. Despite their importance in wildfire management, the nature of future changes to prescribed burn windows under global warming remains uncertain. We use a regional climate projection ensemble to provide a robust spatiotemporal quantification of statistically significant future changes in prescribed burn windows for southeastern Australia. There are significant decreases during months presently used for prescribed burning, that is, in March to May in 2060–2079 versus 1990–2009 across several temperate regions. Conversely, burn windows show widespread significant increases in June to August, that is, months when burns have rarely occurred historically, and also in spring (September–October). Overall, projected changes in temperature and fuel moisture show the most widespread and largest decreases (or increases) in the number of days within their respective ranges suitable for conducting burns. These results support wildfire risk mitigation planning.

Figure 2. (a–l) Changes in the ensemble mean number of days within thresholds for conducting burns in 2060–2079 versus 1990–2009. (a) QLD = Queensland; NSW = New South Wales; VIC = Victoria; SA = South Australia. Significance stippling (a–l): statistically insignificant areas shown in color, (<50% of the models are significantly different from burn days during 1990–2009). In significant agreeing areas (stippled using dots), at least 50% of RCMs are significantly different to 1990–2009, and at least 75% of significant RCMs agree on the change direction. Significant disagreeing areas (at least 50% of RCMs are significantly different, and <75% significant models agree on change direction) shown in color with diagonal lines. Areas where there are no burn days in either period are masked (gray).