In preparing for a lecture on an early spring day in the hills of Victoria, I noticed that male cicadas, usually prompted by summer temperatures, began their mating song months earlier than I could ever remember since childhood. A week later, Queensland was on fire, and many of the blazes were attributed to arson. Despite many being deliberately lit, what followed suggested climate change. The question remained as to how much.
On further investigation, I was further shocked to find that the 2019 fires began in late August, before the usual Queensland bushfire season would start blazing its way down the east coast, six months ahead of the February peak for Australia’s deadliest fires for 200 years.
As well as seasonality, the reach and speed of its journey was “unprecedented”, a word right-leaning commentators immediately attacked.
Misinformation and politics
Andrew Bolt pointed out that the fires were small compared to Australian records since 1851. He ignored the main point about seasonal timing and speed, and went quiet as the fires grew and surpassed historical records. A few little-known grassfires in the Northern Territory were larger in terms of hectares burnt, but even they dwindled into insignificance when height was added to cover three-dimensional biomass.
Alan Jones saved the day for climate sceptics by blaming the fires on arson, using a version of the following logic: If arsonists caused the fires, then climate change didn’t.
This was based on misrepresenting fire investigations and satellite data converging on about 85 per cent of Australia’s 60,000 fires being due to human sources (yet he never mentioned that only 13 per cent were confirmed arson). After being promoted by Breitbart News and an army of right-wing bots spreading misinformation, the same argument was adopted by the Trump administration’s affiliates.
Experts were forced to state the obvious – even after human ignition, the size and ferocity of fires still depends on fuel and prevailing weather. Every cub Scout the world over knew this, but it still took weeks for the arson argument to subside.
The later, larger southern fires started to create their own weather – burning hotter than a Bunsen burner, pyro-cumulus clouds sparked their own dry lightning.
In fact, the 2019 fires would have needed a sudden 60-fold increase in arson to account for Australia’s megafires – an impossibility given tiny 5 per cent increases in arson per year for decades.
The arson argument was rapidly smothered as fires grew, because the later, larger southern fires started to create their own weather – burning hotter than a Bunsen burner, pyro-cumulus clouds sparked their own dry lightning, and embers started fires more than 30 kilometres ahead of the front. This was consistent with past studies that massive fires fed their own growth, with diminishing contributions from arson and other human causes.
At this point, and at another level, the only remaining human cause was climate change. In response, Barnaby Joyce started arguing that the Greens’ policies prevented controlled burning, causing megafires due to higher fuel loads.
Determined conspiracy theorists combined this with the dwindling arson theme, claiming that Greens activists themselves lit the fires to push their own climate agenda. Madness. No activist would consider this, much less risk the species extinction that resulted after more than 1.5 billion animals died in these fires.
In response to the fuel load argument raised by Barnaby Joyce and others, past fire commissioners pointed to research and fire management experience showing that reduced fuel loads from hazard-reduction burns were inconsistent in decreasing seasonal wildfires. Sometimes it works, sometimes not, often in different areas. This is because the issue is extremely complex.
Hazard reduction isn’t just burning, but bulldozing, pesticides, grazing and deforestation. Using contractors with big machinery smashes biodiversity, whereas more careful but labour-intensive approaches include small-scale burning for fire-adapted species.
This level of sensitivity can only be carried out by dedicated groups of local volunteers following similar approaches to Aboriginal firestick burning, because it remains small-scale per participant (compared to modern machinery), so is more focused and sensitive to patches of ecological fragility.
This probably needs more government funding, because the approach is complex at all levels. It first needs to split state areas into much smaller patches that recognise the mix of species, their age, growth rates and fire resilience – all of which go into calculating what’s called the Tolerable Fire Interval (TFI), a measure now much more sophisticated than simple hectares burned. Adopted since 2017 in some states, the TFI pixelates satellite imagery to adjust and apply hazard strategies at granular levels. Despite the cost, Victoria managed to achieve this level of management and was still vulnerable to wildfires in Gippsland, demonstrating just how hard it is to manage bushfire overlays.
Apart from climate change, the last remaining argument, and one that has some merit, is that the fires emerged from a confluence of natural cycles.
Australia was hit by three of its main climate drivers in 2019: the El Nino Southern Oscillation (ENSO); the positive Indian Ocean Dipole (IOD); and the negative Southern Annular Mode (SAM).
The natural cycles that fanned the bushfire flames
El Nino is the hotter phase of the Southern Oscillation Index, measured by air pressure differences between Tahiti and Darwin. The IOD takes a similar approach, but is based on the sea surface temperature anomalies in the Indian Ocean’s tropical west against its southeast. Positive IOD values resemble El Nino, reducing rainfall in Australia’s southeast, and correlating with every Australian drought since 1889. Sometimes they coincide to form a “super El Nino”, which happened in 2019.
The third major driver is SAM, vast westerlies that spin around Antarctica, rising upwards towards Australia in cycles. In 2019 they rose towards Australia in August, causing less rain above Sydney and heatwaves in the southeast. As they rise, they blow across the hot Australian interior, explaining the red dust storms presaging the fires.
There’s no doubt these climate drivers affected drought and fires in Australia; no doubt again that some fires were lit by humans or caused by human activity; again, fuel load would have had a major impact even when properly managed. All converged on Australia’s biggest fires in recorded history, and some part is likely due to climate change as well.
There’s no excuse to remain one of the world’s highest emitters per capita – if developing nations point to Australia as a standard for their own rights to emissions, we would now need almost eight planets to accommodate them.
Here’s a crude estimate of how much climate change might have contributed:
Ignoring fuel and assuming arson followed its usual trajectory, we can presume the remainder of the fires emerged from a combination of natural cycles and climate change. The recently updated McArthur Forest Fire Wildfire Index (FWI) includes temperature, humidity and rainfall, whereas annual data is also available for the three main climate drivers back to 1957 – 60 years of data, all accessible to anyone with an internet connection to BOM.
When the years suffering major fires are compared with all others, all were affected by El Nino, followed by IOD, then rainfall (in other words, drought), followed by SAM. The three natural cycles were involved in 63 per cent of the fires since 1957, whereas rainfall was involved in 20 per cent.
As the single measure of climate change, national temperature anomalies had already risen by one degree in 2020 compared to the average from 1960 to 1990; it transitioned from negative to positive in 1985, and its maxima was linear, suggesting a rise of 1.5 degrees since 1950.
Using this metric alone, the effect of climate change on Australia’s megafires, outside of natural cycles and arson, amounts to 16 per cent. It’s likely much higher, though, as the natural cycles (except in the case of ENSO) are themselves affected by climate change, as can be seen in Figure 1.This simple approach can be calculated by anyone, but is likely a vast underestimate, as the next section demonstrates.
So, what did cause the Australian 2019/2020 mega-bushfires?
At the start of February, the world’s leading science journal, Nature, announced that a global team of scientists, including Australia’s own Dr Sophie Lewis, were working on a complex attribution study to test whether and how much climate change was to blame for the Australian megafires. This study came out last week, buried under news of coronavirus and mass panic relating to toilet paper sales.
Final analyses demonstrated that fully 30 per cent of the increase in the FWI was due to anthropogenic climate change alone.
The authors of this eight-week attribution, led by Geert Jan van Oldenborgh from the Royal Netherlands Meteorological Institute, have now carried out 231 such studies on natural disasters worldwide – storms, heatwaves, floods and now fires.
Four of 11 datasets offered enough Australian data to reach back much further, to 1900. Not all were appropriate due to missing data in temperature, rainfall, humidity or wind speed – the types of factors used to predict catastrophic fires by emergency services. The entire analysis took three steps:
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Temperature using a seven-day moving average for the fire weather (across available years)
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Drought using annual precipitation and driest month (again across available years as above)
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Attribution models on the Fire Weather Index (FWI) and the Monthly Severity Rating (MSR).
They also checked the results against the amount of area burnt in each month of the 2019 fires between the Great Dividing Range and the coast. The models across time and area validated one another, although they didn’t use actual burned area per year.
Final analyses demonstrated that fully 30 per cent of the increase in the FWI was due to anthropogenic climate change alone. Two models converged on a temperature increase of 1.5°C to 1.7°C from 1900 to 2019, plus a massive change in the return rate – the number of years that should elapse between catastrophic events. This fell dramatically from 85 years in 1900, to eight years in 2019.
For Australia, this means more catastrophic fires more frequently.
Outside of climate change, the more natural cycles of the Indian Ocean Dipole (IOD) and the Southern Annular Mode (SAM) caused more than half of the 2019 drought – around one third each – with little impact from the El Nino Southern Oscillation (ENSO). The probability of catastrophe rose by a factor of 11, mostly due to trends in temperature.
Implications for political arguments and misinformation campaigns
These results should put a host of political issues to rest, and also pave the way for adaptation and mitigation strategies – things such as the Australia Institute’s climate disaster levy, reanalysis of our obligations under the Paris Agreement, and a long-overdue reconsideration of Ross Garnaut’s efforts on behalf of the nation.
It should inform what the federal government aims to handle over the next six months – a re-evaluation of our approaches to bushfire, and our commitments under the Paris Agreement.
The Paris Agreement, even if fulfilled, still leaves the world on track for +3°C of warming – and even below this, +2°C would be enough to quadruple the frequency of catastrophic megafires.
The equally important issue of the coronavirus shouldn’t distract us from what the government chooses to do about fires.
As well as the royal commission into the Black Saturday fires, the Deloitte analysis of intangible costs, and many other factors, the government should also take into account two seemingly unrelated reports – the 2019 mass extinction report led by Professor Sandra Diaz, and the 2020 A Future for the World’s Children? report by the World Health Organization and UNICEF, in which Australia fails miserably to protect its own children.
If our children are to avoid ecological catastrophes, the world will have to adapt very rapidly to zero emissions – so rapidly that it would likely lead to resource wars and economic collapse. This means we need to act now if we mean to ease their adoption up to 2050 – to prevent them walking a razor’s edge between natural disaster and war.
For Australia, an interim aim would be to constrain, by 2025, Australia’s emissions to eight tonnes per capita of emissions. There’s no excuse to remain one of the world’s highest emitters per capita – if developing nations point to Australia as a standard for their own rights to emissions, we would now need almost eight planets to accommodate them.
Apart from Australia, the US and a clutch of OPEC nations, the world average is only 2.2 tonnes per capita. Even those who successfully optimised the health of their citizens over the past 60 years needed no more than eight tonnes, and this without any access to renewable technologies.
So why not Australia? If the value of our coal exports ends up less than the rising costs of bushfires, then why not apply a disaster levy, reintroduce Professor Garnaut’s solution, and aim for eight tonnes per person by 2025? At the very least, drop the ingenuous appeal for special consideration based on a confection of carbon credits.
And isn’t it also time to drop the ubiquitous argument of conservative commentators that we also need special consideration because we only emit 1.1 per cent of the world’s emissions. Just wait until China and India claim the same consideration based on our emissions per person – then see Australia furiously back-pedalling as its backyard burns.
If we act now, the cicadas will keep singing, and so will Australia’s children.
