The unusual nature of Australia's Black Summer bushfires may have marked the beginning of a new fire-fuelled "ice age" and the world seems to have "crossed a threshold" to a more dangerous future, a global fire historian says.
Emeritus Professor Stephen Pyne at Arizona State University is a former firefighter in the US who has previously studied Australia's fires for his 1991 book Burning Bush: A Fire History of Australia.
Pyne said the 2019/2020 blazes, which ripped through 24 to 40 million hectares of bushland across multiple states and territories, marked the start of a global year of fires.
"I do think there will be a legacy because the fires were not limited to Australia, they continued to roll over the western United States, they were in Europe and Siberia."
Pyne said the scale of the Black Summer fires made them different to blazes in previous years.
"While none of the individual fires in Australia or elsewhere were unprecedented, I think the scale was different because they came as a swarm."
Previously Pyne thought the Black Saturday fires, which claimed the lives of 173 people in Victoria in 2009, had set the limit for what a single fire could do but last year's fire season swelled into months of sustained burning.
"What made the fires different generally was the swarming effect over a large scale. They weren't discrete outbreaks over two or three days, they continued.
"I think of that as a 'rolling thunder effect'. When they are coming sequentially like that, it just keeps building."
Pyne said California has also been a spectacular example of this, with the state experiencing its fourth consecutive year of historic fires.
He said not all fires had the same causes, the fires in the Amazon were also associated with land clearing and the ones in Indonesia were linked to the draining of tropical peat lands.
"But everywhere the fires seem to be a manifestation of the breakdown of humanity's relationship with the natural world," he said.
"I think we have potentially crossed a threshold this year."
A NEW 'FIRE AGE'
Pyne believes the way humans have managed natural landscapes, combined with how fossil fuels have been treated, may have given rise to a new "ice age".
"We are taking stuff out of our geological past and burning it without understanding the effects, and this is being released into our future."
He said the increasing ferocity of fires was a manifestation of these activities, which are also changing sea levels and causing widespread extinctions of plants and animals.
"We are reshaping the planet directly and indirectly."
In the same way that ice was seen as the physical manifestation of the changes to the Earth's temperatures during the Pleistocene era, fire may become the manifestation of a new era that Pyne is calling the Pyrocene era.
"For the Australian fires, it turns out they were the lead for an extraordinary global year of fires, and can also be taken as an undeniable marker for what I'm thinking about as our new fire age."
Pyne believes that smoke from the fires, which obscured cities like Sydney and Canberra for days, may finally get people to take notice of what is happening around them, in much the same way that dust storms in the 1930s galvanised action on the dust bowls in America.
He said action started to be taken about farming practices when Washington DC began feeling the effects of massive dust storms that travelled all the way from central areas of the US.
"This changed the discourse and it suddenly became a national issue. It gave extra urgency to a lot of conservation programmes and made the problem visible to people and Congress.
"My sense is that smoke will do that for this past year's fire.
"It makes the visibility of impacts apparent to a bigger audience and that could lead to change."
The smoke from Australia's fires reached New Zealand and reportedly other areas around the world, while smoke from US fires travelled to places that people thought were immune to fire, making it a public health issue that it hadn't been before.
"I think people have a high tolerance for images of flames – they are dramatic but are limited to particular places, but the smoke can travel widely," Pyne said.
In this way the Black Summer fires could have an even longer-lasting impact.
"I'm tempted to think they are historical fires but they may also end up being epic fires depending on our response."
Pyne said fire was in our future no matter what we did.
"We've got to control the binge burning of fossil fuels but even once this stabilises or is reversed, there's still going to be a lot of fires and we will have to do a lot more than we have historically.
"They are not going away … we have got a big debt and we have also got to put lots of good fire back into the environment.
"Even if we dial down the burning of fossil fuels and dial up our actions on climate change, there will be a lot of fire in our future.
"It can be wild or devastating, or it can be somewhat controlled and actually produce good benefits.
"But it's not going away."
With the US still dealing with the aftermath of the presidential election, which Donald Trump has still refused to concede, Pyne said Australia was better positioned to take action.
"You are really on the frontlines of this, you're well equipped with world-class fire science and bushfire fighting capability," he said.
"I'm hopeful that Australia can make movement and begin responding in an engaged and informed way, in ways that the US and even Canada can't.
"This is something that Australia can really take the lead on, it can engage with the landscape and fire, and the cultural discussion is also an interesting part of that too."
Pyne said it wasn't just about doing one big thing to solve climate change and fix the problem, there were a lot of little things that can also be done, and these actions may be different in different areas.
"We need to decide what the problem is in each particular place and what set of treatments make sense there."