Fire management in a changing climate
Does climate change make bushfires worse?
The short answer is yes.
The climate (on average) is heating up and there will be an increase in hotter weather, heat waves and significant fire weather with less rain in many parts of southern Australia.
This means there is a need for all of us to improve our understanding of how the impacts of climate change will affect the risk of bushfires, and how we will manage bushfire risk, wildlife conservation and development.
While South Australia’s climate has always been highly variable, a warming trend has been observed since the 1970s. According to the latest data, average temperatures across the state have warmed almost 1.5 degrees Celsius over the past century.
A warming trend doesn’t mean there will be no cool days between the hot ones. There will be cool days along with rainy days, however there will be fewer rainy days and more days of extreme rainfall.
Although fire management aims to reduce bushfire risk, a changing climate will see an increase in days of extreme and catastrophic fire weather near towns and urban areas. This increase will lead to more days when significant bushfires can occur and increase the severity of fires in the future.
How does climate change impact bushfires?
We need to take climate change impacts into account when planning for and managing bushfire risk.
All of South Australia is projected to experience harsher fire weather. This is because projected warming and drying across the state will lead to fuels that are drier and ready-to-burn more often.
Southern South Australia
In southern South Australia, less rain and an increase in dryer, hotter days will lead to an increase in extreme and catastrophic fire weather (Total Fire Ban days).
By 2030, the number of extreme and catastrophic fire danger days is likely to increase around 10% on Eyre Peninsula, Yorke Peninsula and in the Mount Lofty Ranges (Southern and South-Western Flatlands). Increases in extreme and catastrophic fire danger of up to 30% are possible in the Murraylands, Riverland and South East of SA (Murray Basin). In the decades beyond 2030 (2050-90) larger increases are expected.
Dryer conditions over the next few decades, may also start to change bushland areas. One possibility is that many shrubby areas may begin to change to grassy woodlands as grasses are more drought tolerant than shrubs. This shift to grassy fuels means that fires are easier to put out on all but the very windy days when they will spread very fast.
Northern South Australia
In the semi-arid north of South Australia, bushfires follow very wet years when extensive grass growth occurs. In between these events, there is little fuel to burn. The projected increased dryness and less regular, but heavier rain is likely to mean less shrub and grass growth on average. However, when rainfall does occur, it is likely to encourage stronger grass growth, resulting in greater fuel loads the following year. With an increase of storms with lightning, these changes could also lead to an increase in significant bushfires in some areas. This pattern of ephemeral fuel growth followed by bushfire years will continue across the pastoral areas of SA with stronger peaks in rain events likely.
By 2030, the number of days with a extreme and catastrophic fire danger is likely to increase by at least 30% in these areas (Rangelands). The trend of increasing days of extreme and catastrophic fire danger days will continue to 2050 and beyond.
How does climate change impact prescribed burning?
This overall dryer weather is shifting the windows of ‘safe weather’ to conduct prescribed burns. The best burning conditions (i.e. the safest, while still reducing the most fuel) are moving to earlier in spring and later in autumn. This means some changes are going to be needed when firefighters conduct these important burns as they will need to be earlier in spring (late winter) and later in autumn (early winter) in many years.
Outside of prescribed burning seasons, we will continue to use other fuel reduction methods to help protect life and property from fire, and to conserve the natural and cultural heritage resources of South Australia.