Climate Change and Bushfire Risk in Australia: What’s Changing?

What the evidence shows

CSIRO and the Bureau of Meteorology’s latest published State of the Climate report shows that Australia’s climate is continuing to warm. Australia’s land has warmed by about 1.51°C since 1910.

For bushfire risk, one of the most important findings is that extreme fire weather has increased and fire seasons have lengthened across large parts of Australia since the 1950s. The change is particularly important across much of southern and eastern Australia.

The Bureau of Meteorology also reports that dangerous fire-weather conditions are occurring earlier in spring in parts of southern and eastern Australia. Future fire weather is projected to become more severe in many regions as temperatures continue to rise.

Does climate change mean more bushfires?

This question needs a careful answer. Climate change is increasing the conditions that make dangerous fires more likely, but the number of fires that actually start is controlled by more than climate.

The national trend is therefore better described as more dangerous fire weather and longer fire seasons, rather than simply “more fires everywhere”. CSIRO and the Bureau report that this has contributed to larger and more frequent forest fires, particularly in southern Australia, while the pattern differs between regions.

Why a warmer climate changes fire weather

Fire weather becomes dangerous when hot, dry and windy conditions combine with dry fuel. Climate change affects several parts of that equation.

• Higher temperatures: hotter conditions increase evaporation and can dry vegetation and soil more quickly.
• More extreme heat: heatwaves increase stress on vegetation, people and emergency crews.
• Changing rainfall: cool-season rainfall has declined in parts of southern Australia, while northern Australia has become wetter on average in recent decades.
• Lower fuel moisture: dry fuels ignite more readily and can support faster-moving fire.
• Longer dangerous periods: earlier spring fire weather and longer seasons reduce the traditional window between seasons in some regions.

Australia does not have one fire climate

Australia’s size matters. The drivers of bushfire risk in the forests of Victoria or Tasmania are not identical to those across northern savannas or inland grasslands.

In much of southern and eastern Australia, dangerous forest-fire weather is strongly influenced by hot, dry and windy conditions and dry fuels. In northern and central Australia, wet seasons can produce very large grass growth. When that grass later cures and dries, it can support extensive grassfires.

This is one reason national statements need regional context. A wetter year does not automatically mean lower fire risk later. It may reduce immediate forest-fire danger while also growing more fuel in grassland regions.

Climate change and natural climate variability

Climate change is a long-term trend. El Niño, La Niña, the Indian Ocean Dipole and other climate drivers operate over shorter periods and can make individual seasons much wetter, drier, hotter or cooler than the long-term trend alone would suggest.

For example, wetter La Niña periods can temporarily reduce dangerous forest-fire weather in parts of south-eastern Australia. The same rainfall can increase vegetation growth, which may become fuel once it dries.

This is why one mild fire season does not disprove the long-term trend, and one severe season does not by itself prove it. Long-term observations across many decades provide the stronger evidence.

Dry lightning and fire-generated thunderstorms

Lightning without significant rainfall is an important natural ignition source. The Bureau notes that how climate change may alter dry-lightning risk is still an active area of research, so it should not be treated as a settled national trend.

There is, however, evidence of increasing conditions favourable to fire-generated thunderstorms in parts of south-eastern Australia. These pyrocumulonimbus events can produce severe winds, rapidly changing fire behaviour and new lightning ignitions around or beyond the fireground.

Use the current Fire Danger Rating — not old terminology

Australia’s current public Fire Danger Rating System has four action levels: Moderate, High, Extreme and Catastrophic. On minimal-risk days, a No Rating may be issued.

Older terms such as Code Red, Severe and Very High are not current public Fire Danger Rating levels.

A declared Fire Danger Period or Bush Fire Danger Period is separate from the daily rating. Outside a declared period, No Rating is commonly seen when daily risk is minimal, but fires can still occur and local restrictions still need to be checked.

What this means for households and communities

A changing climate makes annual preparation more important, not more complicated. The basics remain effective.

• Know whether you live, work or travel through a bushfire-risk area.
• Check the Fire Danger Rating and official warnings regularly during dangerous weather.
• Review your bushfire survival plan each season and after major changes to your household or property.
• Prepare the property by reducing combustible material and maintaining buildings and access.
• Plan for power, mobile-phone and internet outages.
• Include children, older people, people with disability, pets and livestock in the plan.
• Leave early when your plan or official advice tells you to go.

Climate change does not remove the value of property preparation. It does mean preparation should be reviewed against today’s risk rather than assumptions based on what fire seasons were like decades ago.

What this means for firefighters and emergency managers

Longer periods of dangerous fire weather can affect more than suppression. They can increase the time agencies remain at elevated readiness, reduce opportunities for rest and training, place additional pressure on volunteers and create competition for aircraft, incident-management teams and interstate resources.

For crews, hotter conditions increase the importance of hydration, work-rest management, heat illness controls and monitoring fatigue. Extended campaigns can also create cumulative psychological and physical pressure well after the first fire front has passed.

More overlap between fire seasons can make national resource sharing harder. A crew or aircraft available to assist another jurisdiction in one year may be committed at home during another.

Frequently asked questions

The key message