Australian Bushfires and Climate Change

We review the massive Australian wildfires that raged across NSW and Victoria during the 2019-20 bushfire season. We explain the causes, the ecological damage, including the loss of koalas and other wildlife, as well as the effect of the fires’ huge CO2 emissions on global warming.
Bushfires East Grippsland, Australia
Australian bushfires on the coast of Victoria. January 4, 2020. Photo © Australian Maritime Safety Authority

Widespread Drought and Wildfires

Experts have said that Australia is the ‘canary in the coal mine’ as far as global warming is concerned, and recent Australian bushfires certainly seem to support this view. During the period June 2019 to Feb 2020, Australia experienced widespread drought and wildfires of unprecedented severity, particularly in the southeast of the country, where New South Wales suffered the worst blazes ever recorded. Satellite images posted online from NASA’s Earth Observatory, showed trails of smoke from the Australian fires reaching as far as South America.

The fires were caused by two decades of drought across much of the continent, and by the convergence of several regional climatic variables. Climate change is known to be a key influence behind both these factors, a conclusion supported by the 2019 Arctic fires that swept across Alaska, Canada and Siberia, and by those that hit California later in the year.

According to Australia’s Centre for Disaster Philanthropy, the bushfires devastated an estimated 18.6 million hectares (46 million acres; 186,000 square kilometres; 72,000 square miles), destroyed thousands of homes and killed at least 34 people. 1

Map of Australian Wildfires 2019-2020
Incidence of Australian Wildfires 2019-2020 taken from satellite data. Image: Centre For Disaster Philanthropy/ MyFireWatch

Damage From 2019-2020 Fires

By early March 2020, when all fires in New South Wales had been extinguished and the ones in Victoria, contained – the fires had destroyed over 5,900 buildings (including 2,779 homes) across Queensland, New South Wales, Australian Capital Territory, Victoria, South Australia, and Western Australia. More than three-quarters of the Blue Mountains World Heritage area in NSW and half the Gondwana world heritage rainforests in Queensland were destroyed.

The worst-hit states were New South Wales (NSW) and Victoria. In NSW, 5.4 million hectares (13 million acres) were destroyed, including 2,439 homes. Sydney itself experienced its first ever ‘catastrophic fire conditions’ with fires spreading to several of its suburbs. In Victoria, more than 3,500 fires were recorded, and 1.5 million hectares were burnt. None of the other states suffered as much damage, although the Northern Territory experienced an average bushfire season, in in which around 6.8 million hectares (17 million acres) were burnt, underscoring the typical power and range of wildfires in the more remote areas of this huge continent.

Loss of Biodiversity From Bushfires

The wildfires caused a catastrophic loss of biodiversity among animals. According to an estimate from Professor Chris Dickman, an ecology expert and a fellow of the Australian Academy of Science from the University of Sydney, as many as one billion animals died, of which 800 million perished in New South Wales alone. It is thought that one third of all koala bears (Phascolarctos cinereus) were wiped out, including 20,000 koalas in a single reservation. 2 Dickman’s estimate is based on animal population density statistics from a 2007 World Wide Fund for Nature (WWF) report on Australian wildlife. (Note: the WWF report shows that, on average, there are 17.5 mammals, 20.7 birds and 129.5 reptiles in every hectare/2.5 acres). According to RMIT ABC News Fact Check, Dickman’s estimate is a conservative one. 3

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Satellite image of fires on Australia's Kangaroo Island
Satellite image of Australian bushfires on Kangaroo Island, January 7, 2020. Notice the smoke plume being blown in a westerly direction. Image: © NASA Worldview

On Kangaroo Island, for example, a third of the land went up in flames, including protected areas home to penguins, kangaroos, koalas, possums, Ligurian bees, Kangaroo Island dunnarts, southern brown bandicoots, and various endangered species of birds, including glossy black cockatoos. According to NASA, as many as 25,000 koala bears perished. The island is also home to purebred, disease-free Ligurian honey bees. Tragically, a quarter of these super pollinators are believed to have been wiped out by the fires. Experts say it could take decades or longer for the island to recover.

For more about how to reconcile the moral rights of human and animals, as well as several other ethical issues, see our article on the ethics of climate change.

Carbon Emissions From Australian Bushfires

In April 2020, the Australian Government’s Department of Industry, Science, Energy and Resources published a preliminary estimate of net greenhouse gas emissions produced by the fires – up to Feb 11, 2020 – of roughly 830 million tonnes of carbon dioxide equivalent (MtCO2e). By comparison, Australia’s entire annual emissions for 2016 were 414.9 million tonnes – just under half the carbon dioxide emitted by the fires. In January 2020, the British Meteorological Office stated that Australia’s 2019-2020 wildfires were expected to contribute 2 percent to the increase in the atmospheric level of carbon dioxide, which is projected to reach 417 ppm – one of the largest annual increases in atmospheric CO2 on record. 4

According to David Bowman, Professor of pyrogeography and fire science at the University of Tasmania, so much damage has been caused that Australian forests may take more than a century to re-absorb the carbon that has been released in a single fire season.

Air Pollution in Sydney, Canberra, Melbourne

On December 8th 2019, giant smoke clouds approached Sydney, causing the air quality index (AQI) in western suburbs to exceed 2,550 – 12 times the hazardous level of 200 – as the city choked on a level of toxic air pollution previously seen only in places like India and China. This type of air pollution from burning wood is characterized by high levels of particulate matter, including microscopic particles of black carbon, that can penetrate into the deepest part of the lungs. 5

On 1 January 2020, the air quality index in Monash, a suburb of Canberra, was measured at 4,650, or more than 23 times hazardous level, as the city was engulfed in smoke. The AQI finally peaked at a frightening 7,700. According to Dr Paul Dugdale, Canberra’s acting chief health officer, the air pollution was the worst since air quality monitoring started in the city 15 years ago. 6

Ten days later it was the turn of Melbourne, where AQI levels were also for a time the worst in the world. See also: Health Effects of Air Pollution.

Global Air Pollution

On the same day that Canberra was suffering, a layer of smoke and ash from the Australian fires blanketed the whole of New Zealand’s South Island, (1,300 miles away), in an orange-yellow haze, coating the region’s glaciers a light brown color. New Zealand’s Weather Watch talked about an “unprecedented plume of smoke”, saying “smoke this thick has never crossed New Zealand from Australia in recorded history”. A week later, the smoke cloud was over Chile, Argentina and Brazil, 7,000 miles away. Compare this with the Asian Brown Cloud which moves across the Indian sub-continent, Bangladesh, Pakistan and China.

Total Cost of the Australian Bushfires

The total cost of the fires is expected to exceed the A$4.4 billion of the Black Saturday fires, the ones that burned across the Australian state of Victoria on and around Saturday, 7 February 2009. Shane Oliver, of AMP Capital, an Australian-based investment management company, said that a “1 percent drop in Australia’s gross domestic product could wipe an estimated $20 billion from the economy, plus a further $20 billion resulting from damages to agriculture, property, livestock, factories, plantations and cars.” For example, a minimum of 100,000 sheep and more than 25,000 livestock perished in the Kangaroo Island fires alone. The fishing and tourism industries were also hit hard.

Is the 20019/2020 Bushfire Season the Worst Ever in Australia’s History?

No. From a statistical viewpoint, the 20019/2020 wildfires were not wholly unique among the 230-year history of European settlement in Australia. They didn’t burn the most land, and they didn’t cause the greatest loss of life. But their ferocity, size and environmental impact puts them among the worst – a view supported by the majority of fire chiefs on the ground.

What’s more, the wealthy, experienced and well-equipped Australia of 2019 – armed with up-to-date satellite information and other data on the state of the countryside – was a very different place from the Australia of 1974, the record-breaking bushfire year. Back then, neither the government nor the people had any idea that the fires had been so destructive, since most occurred in isolated areas. Compare that with the 2019-2020 fires which occurred in the most heavily populated states and even blanketed the nation’s capital with smoke.

Wildfires in Australia are a regular occurrence. In fact, much of the continent. as well as its unique biodiversity, has been shaped by low rainfall and extreme heat. But as Australia’s Climate Council said in a recent report – what happened in 2019-2020 was “not normal”. The unprecedented nature of the fires can be seen through their intensity and geographical spread, the extreme dryness of the forests and very low rainfall, as well as record-low levels of soil moisture and air pollution. The abnormality of the weather is also illustrated by the fact the fires burned areas of rainforests, wet eucalyptus forests, and swamps which no fire had ever burned before – at least not for a thousand years. In New South Wales, a record 5.4 million hectares of forest and bush were destroyed – 50 percent more than in previous worst fires of 1974.

Which Was Australia’s Worst Ever Bushfire Season?

The worst year in terms of amount of land burnt, was 1974-75, when around 117 million hectares (290 million acres) burned – equivalent to the area of France, Spain, and Portugal combined. However, the 1974–75 season affected mostly arid areas and grasslands, while the main impact of the 2019–20 fires was on forested land. In addition, most of the 1974-75 fires were in remote areas, so that many people were only vaguely-aware of what had happened. Indeed, it was only after satellite images revealed the full extent of the fires that Australian authorities themselves were aware of the devastation.

What Were the Causes of the 2019-2020 Australian Bushfires?

The fires were caused by a combination of five factors (in no particular order):

First, a positive Indian Ocean Dipole (IOD) event in which unusually cold sea-surface temperatures in the eastern Indian Ocean shut off the normal humid airflow to the north of the country. This exacerbated the ongoing drought in eastern and southern parts of the country.

A strong El Niño-Southern Oscillation event amplified the IOD impact, although Australia’s worst bushfire seasons tend to be more affected by IOD patterns than by El Nino or La Nina events in the Pacific.

A second cause, was a positive trend in the Southern Annular Mode (SAM), during which the usual westerly winds moved further south than normal. This diverted rain-bearing fronts and low-pressure systems from bringing rain to southern Australia.

A third cause, was an unusual event which started in the last week of August 2019 in the atmosphere above Antarctica, known as “sudden stratospheric warming“. The upper atmosphere above the South Pole heated up from close to minus 70 degrees to about minus 25 degrees Celsius. The ultimate effect of this event was to create drier, warmer conditions in New South Wales and Southern Queensland.

A fourth cause, was the ongoing drought in southeastern Australia, where winter rains have failed three times in a row. This has never happened before, even during the decade-long Millennium Drought. So severe was the drought, that it even dried out many of the wet rainforests, some of which burned for the first time in centuries.

Map showing rainfall deficiency in Australia
Map of Australia with rainfall deficiency highlighted in yellow (serious shortage), orange (severe) or red (worst ever). Drought is a major cause of Australian bushfires. Image: Australian Government Bureau of Meteorology 7

The year 2017 was drier than average for inland Queensland, the bulk of New South Wales, and eastern and central Victoria. In 2018, annual rainfall was extremely low over the southeastern quarter of the country. New South Wales was 100 percent in drought in August 2018, and more or less remained so until the fires. By May 2019, Queensland was 65.2 percent in drought, while southern parts of Western Australia were declared “water deficient” after months of drought. Other drought-affected areas included eastern South Australia as well as central and east Gippsland, Victoria.

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Meantime, rainfall deficiencies in the Murray–Darling Basin, Australia’s largest river system, dropped to the third lowest on record. By July 2019, the Australian Bureau of Meteorology (BOM) stated that the drought was now officially the worst on record in the Murray–Darling Basin, and “had now exceeded the Federation Drought, the WWII drought and the Millennium drought in terms of its severity. 8 In October 2019, Australia’s Bureau of Meteorology (BOM) warned that drier than average conditions would persist at least until the end of the year in most of the drought affected areas.

A graphic warning of the growing severity of the drought in the south-east, was the three mass fish deaths at the Menindee lakes (2018-19). The tragedy has distinct echoes of an earlier disaster on the Darling River (1991-92), when a massive outbreak of blue-green algae poisoned hundreds of kilometres of the river. In a broader sense, the recent fish deaths were another illustration of how decades of warnings from scientists can often go unheeded by the authorities.

A fifth cause, severely aggravating the effects of low rainfall, was the record breaking run of above average monthly temperatures, lasting 36 months to October 2019. 9

Did Climate Change Cause the Australian Bushfires of 2019-2020?

Does climate change cause wildfires? No, not directly. Climate change is a critical global “influence” on Earth’s climate system, and it can be a direct cause of certain problems (such as ocean warming and ocean acidification) but it is rarely a direct cause of extreme weather events like wildfires or hurricanes.

Satellite image of Australian wildfires 2019-2020
Satellite image of Smoke and ash cloud from the 2019-2020 Australian bushfires drifting across the Pacific Ocean. Image: NASA

However, this doesn’t mean that climate change had no effect on the fires. It simply means there is no direct causal connection. After all, a dry forest can be moistened by rain, and also not all arid regions experience wildfires – there has to be something to burn. In addition, climate models are not yet sophisticated enough to decipher the complexities of climate science with the necessary degree of confidence.

Even so, man-made climate change does have a significant “influence” on climate variability around the world. For example, climate change is already reshaping the evolution and intensity of El Niño events to produce more “super” El Niños, causing more damage. 10 Climate change is also increasing the frequency and intensity of positive IOD events. 11

The role of anthropogenic climate change in the working of the Southern Annular Mode (SAM) is also clear. Several studies have also identified a clear link between the poleward migrations of the Southern Annular Mode (SAM) and greenhouse gas emissions, as well as ozone depletion. 12 13

Finally, as the Arctic fires of 2019 demonstrated, a decade of elevated temperatures caused by global warming creates the perfect conditions for fires to take hold – even in damp or wet peat bogs. Since the 1970s, rainfall in the southwest of Australia has declined by around 20 percent, while since the mid-1990s, southeast Australia has experienced a 15 percent decline in late autumn and early winter rainfall, and a 25 percent decline in average rainfall in April and May.

Climate Change Warnings to Australian Policymakers

Scientists have been issuing warnings to Australian policymakers for years. Not least because it’s quite clear that rising temperatures result in greater evaporation, thus drying out the soil and the forest biomass, and creating tinderbox conditions.

In 2007, for instance, the Intergovernmental Panel on Climate Change (IPCC) stated that due to climate change, Australian heatwaves and fires were virtually certain to increase in intensity and frequency. 14

In 2008, Australia’s own Garnaut Climate Change Review (2008) stated: “recent projections of fire weather suggest that fire seasons will start earlier, end slightly later, and generally be more intense. This effect increases over time, but should be directly observable by 2020.” 15

In 2013, the Australian Bureau of Meteorology said global temperature projections indicate that Australia will experience more extreme heat and increasing frequency of bush fires, because of climate change. 16 Further studies confirmed the link between rising temperatures and Australian climate change. 17

In 2014 and in 2019, the IPCC repeated their earlier warning in their Fifth Assessment Report (2014) and in their Special Report on Climate Change and Land (2019), saying that Australia is likely to experience higher air and sea surface temperatures and more heat extremes, both of which necessitate urgent climate change adaptation measures, as well as a more serious approach to climate change mitigation in the future. 18

The bushfires show what happens to carbon emissions and the global environment, when climate denial overrules climate science in the halls of government.

NOTE: To understand why governments and corporations are dragging their feet over climate action, please see: Root Cause of Climate Change.

Burnt undergrowth in Victoria after Australian bushfires. 2020.
Aftermath of bushfires in Australia. 2020. TerriAnneAllen/Pixabay

Impact of Climate Change on Australian Bushfires (2019-2020)

More than 20 percent of Australia’s forests burned during the summer’s bushfire catastrophe, a proportion which is unprecedented globally, according to new research. 19

A recent study, for example, finds that about 21 percent of the total area covered by Australian forests – excluding Tasmania – was burnt in the 2019-20 bushfire season. A dramatic increase over experiences elsewhere. Forests in Australia and other continents have lost up to 5 percent of their area each year, with higher percentages of 8 to 9 percent only recorded in small forest regions of Africa and Asia. Yet in Australia’s 2019-2020 season, the total area burnt jumped to 21 percent.

“The data point for this year’s fires show it stands out completely from all other years for Australia or other countries,” Matthias Boer, the study’s lead author, said. “This is a globally unprecedented scale of burning, not observed in any other forest biome over the last 20 years. There is just nothing like it out there and we felt confident to call it unprecedented.” 20

Another recent study suggests that “there is no doubt that the record temperatures of the past year in Australia would not be possible without anthropogenic influence”, adding that “under a scenario where emissions continue to grow, such a year would be average by 2040 and exceptionally cool by 2060”. 21

Other scientists consider that Australia’s extreme bushfire season was at least 30 per cent more likely than a century ago because of climate change, and, if global warming increases by 2 degrees Celsius, it will be eight times more likely to happen. 22 For more about the effect of incremental climate changes, see: Why Does A Half-Degree Rise in Temperature Make Such a Difference to the Planet?

According to Professor Chris Dickman: “What we’re seeing is the effects of global warming. Sometimes, it’s said too that Australia is the canary in the coal mine with the effects of climate change being seen here most severely and earliest, as well. We’re probably looking at what climate change may look like for other parts of the world.”2

What Does Australia’s Climate Council Say?

In a briefing paper entitled “This Is Not Normal”, published several weeks before the fires peaked in Dec-Jan, the Climate Council – Australia’s leading climate change body – made the following points. 23

• For over 20 years, scientists have warned that climate change increases the risk of extreme bushfires in Australia. This warning was accurate. Unless effective climate action is taken, scientists expect extreme fire weather will continue to become more frequent and severe without substantial and rapid action to reduce greenhouse gases in the atmosphere.

• The catastrophic, unprecedented fire conditions currently affecting the country have been aggravated by climate change. Bushfire risk was heightened by record droughts, very dry fuels and soils, and record-breaking temperatures.

• Climate change is lengthening the bushfire season. The northern and southern hemisphere wildfire seasons are now overlapping, making it difficult to pool resources. And with all year-round bushfires, the opportunity for hazard reduction burning is closing.

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  18. “Australasia.” IPCC Fifth Assessment Report: Working Group II: Chapter 25 []
  19. In the line of fire.” Nat. Clim. Chang. 10, 169 (2020). []
  20. Unprecedented burn area of Australian mega forest fires.” Matthias M. Boer et al. Nature Climate Change (2020). []
  21. A fiery wake-up call for climate science.” Sanderson, B.M., Fisher, R.A. Nat. Clim. Chang. 10, 175–177 (2020). []
  22. Attribution of the Australian bushfire risk to anthropogenic climate change.” Geert Jan van Oldenborgh, et al; Natural Hazards and Earth System Sciences. 2020. []
  23. The Facts About Bushfires and Climate Change.” Australian Climate Council. []
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