Bushfires & Climate Change: The Science

Due to climate change, deadly wildfires have become more common across the world.

Through 2019 and 2020 Australia suffred through unprecedented fires which burned over 24 million hectares, destroyed over 3000 homes and claimed the lives of 33 people. The smoke coverage that spread across the country's major cities has been linked to many more deaths.

According to the 2020 State of the Climate Report, the Australian fire season is expected to grow 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.

The increasing number and intensity of bushfires has been 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.

2019 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.

The Royal Commission into the 2019/2020 fires warned that the length of the fire season has increased in recent decades. The fire weather season now arrives more than three months earlier than in the mid-twentieth century in some parts of Australia. This has reduced the window in which forest management, like perscribed burnings, can be safely completed.

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.