Wildfire · South-eastern Australia
Black Summer: Australia on fire
In the Australian summer of 2019–20 fires burned along almost the whole south-east of the continent, from Queensland to Victoria. They were fed by a drought that had dried the forests for three years and by a spring and early summer of record heat. Over New Year towns on the coast of New South Wales and Victoria were cut off, people sheltered on beaches under a red sky, and the smoke turned the air of Canberra into some of the worst in the world.
November 2019 – January 2020 · New South Wales and Victoria, Australia · CAMS, ERA5
754µg m⁻³
PM2.5 near Canberra, 29 Dec
CAMS daily mean at the nearest grid point; the normal there is 13.
+30%
Fire weather risk
At least 30 % more likely in today's climate than in 1900, mostly through hotter extremes.S1
What happened
The fires began early, in September, in the north of New South Wales, and by December they ran along the Great Dividing Range from Queensland to Victoria. On the hottest days, with strong north-westerly winds ahead of cold fronts, fires grew by tens of thousands of hectares in a day and made their own thunderstorms, which threw embers kilometres ahead and lit new fires.
Over New Year the fires reached the coast. Thousands of people were evacuated, some by navy ships from Mallacoota. The fires killed 33 people directly, destroyed thousands of homes and an estimated billions of animals, and burned an area larger than many European countries.
A dry year, a hot summer
In ERA5, Canberra received about 410 mm of rain in 2019, against a 1991–2020 normal of 640 mm: the second driest year of the period. Much of inland south-eastern Australia was drier still. On 30 December hot air from the interior was drawn south-east ahead of a front, and temperatures passed 40 °C across New South Wales and Victoria.
An attribution study found that weather as dangerous for fire as in 2019–20 had become at least 30 % more likely since 1900, mostly because heat extremes are hotter; the models disagree on the role of drought.S1
Smoke over the sea
The westerly winds carried the smoke out over the Tasman Sea. In the first days of January it tinted the glaciers of New Zealand brown, and within weeks it had circled the southern hemisphere. The largest fires made pyrocumulonimbus clouds that injected smoke straight into the stratosphere, where sunlight heated it and it rose for weeks, up to 35 km.S2
Canberra's air
×58
CAMS daily PM2.5 near Canberra on 29 December 2019, against its December normal of 13 µg m⁻³. Canberra lies in a valley ringed by forest; for weeks the smoke settled in it.
| Day | PM2.5 |
|---|---|
| Dec 28 | 320 |
| Dec 29 | 754 |
| Dec 30 | 380 |
| Dec 31 | 265 |
| Jan 1 | 413 |
| Jan 5 | 492 |
| December normal | 13 |
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References
News
Studies and guidelines
- S1van Oldenborgh, G. J., et al. (2021). Attribution of the Australian bushfire risk to anthropogenic climate change. Natural Hazards and Earth System Sciences, 21, 941–960.How climate change altered the risk of fire weather like that of 2019–20.
- S2Khaykin, S., et al. (2020). The 2019/20 Australian wildfires generated a persistent smoke-charged vortex rising up to 35 km altitude. Communications Earth & Environment, 1, 22.The smoke that reached the stratosphere and rose to 35 km.