According to the 2018 State of the Climate Report, the Australian fire season has grown in length and intensity. The number of days in the most extreme 10 percent of fire weather has increased in recent decades, particularly in southern and eastern Australia.
Increasing numbers and intensity of bushfires are accompanied with trends of drier conditions and less rainfall in southwestern and southeastern Australia.
The report explicitly notes the contribution of climate change to these changes.
How does climate change contribute?
The most conducive fire weather is hot, dry and windy.
2018 was Australia’s driest year on record since 1965. According to Joelle Gergis, a fellow at the Australian Research Council Centre of Excellence for Climate Extremes at the University of Melbourne, the nature of Australian droughts are changing. As the planet continues to heat up, droughts are getting much hotter. This not only exacerbates the dryness, but sets the perfect conditions for extreme bushfires. Director of Environmental Sciences at Clark University in Massachusetts, Christopher Williams states that, "Besides bringing more dry and hot air, climate change - by elevating evaporation rates and drought prevalence - also creates more flammable ecosystems."
Dry weather means more dead trees, shrubs and grass – hence more food for the fire. As the conditions change, plants that have generally relied on humidity to survive have started to disappear and are replaced with more flammable plants that can withstand dry conditions.
Additionally, warmer weather means more lightning, which is the cause of many fires.
All of these factors contribute to more prolonged and intense bushfire seasons.