Australian Bushfires

The Black Summer: An Unprecedented Australian Bushfire Season

Fire and fire management has historically been part of the this continents fabric. Ecosystems have adapted to fire from the regeneration of Eucalpyt forests to triggers for Leptospermum seeds to germinate after a fire event. However, Australia experienced unprecedented fires during the 2019-20 bushfire season, September to March, caused by a combination of extreme heat, prolonged drought, and low humidity. Now commonly referred to as the Black Summer fires, over 18 million hectares were burnt across multiple states and territories, significantly severe in southern and eastern Australia. For weeks at a time, large areas of native forest burnt out of control as firefighters, supplies, and equipment were called in from around Australia and other countries to relieve exhausted local crews.

These extensive and long-endured fires included both Australia’s largest ever fire at Gosper’s Mountain and the largest total burnt area in a single recorded fire season. And, with economists estimating that the bushfires may cost over A$103 billion in property damage and economic losses, they also rank as Australia’s costliest ever natural disaster. This article explores the extent of the 2019-20 Australian bushfires, looking at their causes and impacts, as well as ways to prepare for future bushfire seasons.

What Caused the Bushfires in Australia of 2019-20?

The predominant cause of ignition of fires during the 2019-20 bushfire crisis was lightning strike.  Although arson was speculated to have been a major cause, in reality it had little impact, accounting for around 1% of NSW fires and 0.03% of Victorian fires by 18 January 2020.

Once ignited, though, the unprecedented intensity and rapid movement of the fires came down to two primary reasons: severe ‘fire weather’, warmer and drier than average; and low moisture in vegetation.

The severe ‘fire weather’ of 2019 – strong winds, low humidity, and high temperatures – meant that the risk of bushfires starting and spreading out of control was at its highest. High temperatures were a particular concern with Australia experiencing its hottest year on record that year averaging 1.52C above the 1961-1990 average. New South Wales, one state hit the hardest by the bushfires, broke its record by an even greater margin. There, temperatures were 1.95C above average, beating the previous record year, 2018, by 0.27C.

Australia also had its driest ever year in 2019. Based on records going back to 1900, rainfall was 40% lower than average. Many parts of southern and eastern Australia particularly had been experiencing ongoing draught for multiple years – the most severe on record for some fire affected areas.

The combination of heat and drought caused critically low moisture in vegetation, including trees, grasses, bushes, and leaves. The abundant and drier than usual vegetation then acted as fuel, intensifying the fires and the rate of their spread. Meanwhile, normally damp gullies and rainforest patches were unable to provide their usual impediment to the spread of fire across the landscape.

These conditions causing the extent and severity of the fires are likely to have been exacerbated by long-term trends of warmer and dryer weather caused by climate change.  At a very basic level, rising levels of greenhouse gases in the atmosphere change the Earth’s radiation balance, allowing less heat to escape and thus boosting the risk of hot, dry weather. The impact of climate change has led to longer, more intense fire seasons and an increase in the average number of elevated fire weather days, as measured by the Forest Fire Danger Index.

Impacts of the Bushfires

The Black Summer fires had a number of devastating impacts on the environment, human and animal life, property, and air quality. The fires burnt approximately 18.6 million hectares across Australia – an area greater than the entire surface area of South Korea, Scotland and Wales. NSW was the largest state effected with overall 5.4 million hectares burned, making up approximately 6.82 per cent of the state.   

Thirty-three deaths occurred as a result of these fires, including nine firefighting personnel. The fires also destroyed over 5,900 buildings, including 3100 homes nationwide. The majority of these losses occurred in New South Wales: 25 people died, and 2,439 homes were destroyed in the state.

The ecological effects across the country were also massive. According to a study released by scientists from several Australian universities, nearly three billion mammals, birds, reptiles and frogs combined were killed or displaced by the devastating fires. This excludes insects, the loss of which has been reported to be in the ‘hundreds of billions’. Ecologists fear that the fires have had such a significant impact on many rare or threatened animals, plants, and insects, that some of the losses are feared to be permanent.

As fires burned across the southern and eastern states, for weeks smoke blanketed many Australian cities and air quality dropped to hazardous levels far exceeding national air-quality standards. From October to December, Sydney broken into the top ten most-polluted major cities with parts of the city experiencing air quality up to 12 times the hazardous level. In January 2020, Canberra measured the worst air quality index of any major city in the world with more than 23 times the hazardous level. Melbourne and Brisbane were also heavily affected.

All up, about 11 million Australians reported some exposure to smoke caused by the bushfires. Smoke exposure and inhalation can directly threaten human health even during relatively short exposures. It’s unclear what the long-term health impacts will be, but bushfire smoke contains carcinogens such as benzene and formaldehyde as well as air pollutants such as particulate matter. This can cause issues ranging from eye and respiratory tract irritation to more serious disorders, including reduced lung function, bronchitis, exacerbated asthma, and premature death.

How Can We Prepare for Future Fires?

Nearly all fires were extinguished by the end of February 2020, with rainfall events occurring across much of southern and eastern Australia. However, climate studies have shown that conditions in Australia for extreme bushfires will only get worse as more greenhouse gases are added to the atmosphere. This raises the need to plan to better manage fire risk and the effects of climate change in the future.

Controlled burns will be an important element in managing these risks in the future. Controlled burns intentionally set in cooler conditions, usually after recent rainfall, to create slow-moving, low-severity fires in carefully selected areas. Doing so can reduce fuel build-up in the undergrowth helping to reduce the likelihood of ignition and spread of serious hotter fires.

Historically, Australia’s Indigenous population have conducted these types of burns to maintain plant and animal species that they rely on for survival. For thousands of years, nomadic Aboriginals’ burning of surface vegetation successfully constrained the scales of fires started naturally by lightning. When burning is skilfully carried out in the correct season it can reinvigorate ageing vegetation communities, encourage flowering and seeding and provide a flourishing of new green shoots and highly nutritious small herbs

Some small-scale successes in managing bushfire activity have already taken place. The most notable have combined traditional methods with modern technologies including satellite mapping and controlled aerial ignition using helicopters or drones.

Other things can also be done to limit wildfires and their impacts. Areas of focus should include enhancing early warning systems and fire prediction capabilities, launching public awareness campaigns on the dangers posed by climate-fuelled bushfires and necessary prevention measures, and developing more stringent building codes that address climate risk.

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Published December 2020. Updated December 2021