Technology & Science

'It's unprecedented': What is behind Australia's devastating fires?

Australia continues to burn after more than a month of raging bushfires, and it doesn’t appear the smoke-filled skies will be clearing any time soon. But what's making the fires so calamitous?

Much of the country has been in a persistent drought but there are other reasons

More than five million hectares have burned in Australia, and the bushfires show no sign of abating as it heads into another weekend of hot weather. (AAP Image/Dan Himbrechts via Reuters)

Australia continues to burn after more than a month of raging bushfires, and it doesn't appear the smoke-filled skies will be clearing any time soon.

As of Friday, more than five million hectares have burned, 19 people have died and 21 people are missing. Tens of thousands of people were forced to flee their homes. More than eight million more were under an emergency order.

While Australia is no stranger to bushfires, this one has captured the world's attention. Images of burnt-out cars, people fleeing homes, a parched koala desperately drinking from a cyclist's water bottle and angry townspeople screaming at Prime Minister Scott Morrison for more action are making global headlines.

And there's a good reason for the attention.

"In my experience of doing this fire monitoring, in some places you see intense fires over quite large areas maybe for a week or a few weeks, but to see them for four months in one particular place … it is quite surprising," said Mark Parrington, a senior scientist at the European Centre for Medium-Range Weather Forecasts (ECMWF).

"We only have 17 years of [CO2 emissions] data," said Parrington, who works in the Copernicus Atmosphere Monitoring Service Development Section at ECMWF analyzing wildfire emissions, among other sources. "But in that context then, yeah, absolutely, it's unprecedented."

Australia has been experiencing warmer, drier conditions lately — a result in part to something called a Positive Indian Ocean Dipole, a phenomenon similar to El Niño. 

As a result of westerly winds in the equatorial region weakening, warm water from the deep ocean shifts towards Africa from the Indian Ocean and cool water rises up in the east. For Australia, this temperature difference means drier and hotter weather for much of the continent. 

Fingerprints of climate change

However, that's not the only factor. The country has been experiencing long-term drought conditions, even when there isn't a positive dipole. In Eastern Australia, which includes New South Wales, Queensland and Victoria where the fires are the worst, rainfall has been the lowest on record.

New South Wales alone has been the driest on record with rainfall 36 per cent below the 1961–1990 average, according to Australia's weather and climate agency. 

The Murray-Darling Basin that stretches from Queensland southwest to South Australia, has experienced the driest 34 months on record, compared to other 34-month records starting in January. Victoria, where a state of disaster was declared, has also had its driest 34 months on record. 

The fear is that the fingerprints of climate change are all over this.

Like the rest of the world, Australia is dealing with the consequences of a warming planet. Since 1910, the average temperature for the country has warmed by 1 C. Preliminary data from Australia's Bureau of Meteorology (BoM), suggests that in 2019 the annual temperature in that country was 1.52 C above average. (The official report is set to be released on Jan. 9.) 

If the data holds, it will blow out the record high set in 2013 when the annual temperature was 1.33 C above average.

"The duration, frequency and intensity of heat waves have increased across large parts of Australia since 1950," the Australian government reported. "There has been an increase in extreme fire weather, and a longer fire season, across large parts of Australia since the 1970s."

Trends from 1978 to 2017 in the annual (July to June) sum of the daily Forest Fire Danger Index — an indicator of the severity of fire weather conditions. Positive trends, shown in the yellow to red colours, are indicative of an increasing length and intensity of the fire weather season. (Australian Bureau of Meteorology)
 

Renowned climatologist Michael Mann, a professor of atmospheric sciences at Penn State University, was in Australia during the fires. In a recent opinion piece in the Guardian, he described "smoke-filled valleys" and "brown haze." 

"What is happening in Australia is a harbinger for other countries — a taste of what our future will look like if we don't act now," Mann told CBC News.

Of particular concern to him is the planned Adani coal mine in Queensland (also known as the Carmichael mine) that would be one of the biggest in the world. And that mine could release more than 4.49 gigatonnes annually of CO2 — the leading contributor to the climate crisis. The carbon dioxide emissions would be among the "highest in the world for any individual project," according to a 2011 joint report to the Land Court of Queensland.

Far-reaching consequences

Parrington recalls one of Australia's worst fires, known as Black Saturday, which in 2009 killed 173 people in Victoria, injured 414 and killed more than a million animals, both wild and domesticated.

The human death toll pales in comparison thus far, but Parrington says the peak of the fires lasted just a few days.

"But the fact that this has been going on for several weeks, is really concerning, particularly as a lot of [fires] are occurring upwind of large population centres," he said.

It's particularly the scale of the current fires and number of people impacted, including those in New Zealand, where smoke from the fires has drifted, that concerns him. And that smoke can produce toxic chemicals like benzene and hydrogen cyanide, Parrington said. 

This image, taken using NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) camera on the Terra satellite shows smoke from the Australian fires drifting over, and past, New Zealand. (NASA/Terra/MODIS)

Then there's the effect on glaciers.

The reflectivity of an object is referred to as the albedo. In the case of ice, its white surface reflects solar radiation, and it stays cool. But if the ice darkens for some reason — say, if black soot falls on it — that warms it up.

"Once it gets into the upper troposphere [lowest layer of Earth's atmosphere], it can get picked up by the jet stream there and be transported thousands more kilometres," Parrington said. "If there is transport to Antarctica … any deposition of soot or black carbon to the ice would mean a change to the albedo and potential acceleration of the melting, local to where that deposition took place."

What the future holds is much worse in the absence of concerted action on climate.- Michael Mann, climatologist

Already, the Australian fires have changed the albedo on glaciers in New Zealand.

And the world's glaciers are already threatened with climate change

So, is this a sign of things to come?

"What the future holds is much worse in the absence of concerted action on climate," Mann said.

About the Author

Nicole Mortillaro

Senior Reporter, Science

Nicole has an avid interest in all things science. As an amateur astronomer, Nicole can be found looking up at the night sky appreciating the marvels of our universe. She is the editor of the Journal of the Royal Astronomical Society of Canada and the author of several books.

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