Scarcely have the embers died down than the political fire flares up.

A Liberal senator suggested that "eco-terrorists" might have been to blame. Former Turnbull government minister Concetta Fierravanti-Wells put it as a question - but posing the question puts it into the public arena, most importantly into the dark and poisonous social media ecosystem.

"Given the loss of life, the extensive loss of property and the economic impact, was eco-terrorism an agenda item at any of the recent meetings of the national security committee of cabinet?" she asked.

So what do the facts say?

She does have some basis for suggesting arson as a cause - but no basis for suggesting "eco-terrorists".

She is correct in saying that the most robust research on bushfires suggests that many of them are caused by arson (and she may be right to moan that this research is ignored by leftish publications).

A study by the Australian Institute of Criminology found that half of bushfires in the period studied were either deliberately caused or "suspicious". The big study was done more than ten years ago but there's no reason to think the pattern has changed.

"For all vegetation fires for which there is a cause recorded, fifty per cent may be lit deliberately," it concluded.

Natural causes were only responsible for six per cent.

Nearly 40 per cent were caused by human beings but through carelessness or simple bad luck - and that fits with Canberra's experience: the Australian Defence Force has admitted that the Orroral Valley fire south of Canberra was probably sparked by the landing light of an MRH-90 Taipan helicopter.

And the fire between the city and Queanbeyan was caused when a beekeeping operation near the airport went wrong. It was reignited when a power cable fell.

Neither beekeepers nor soldiers are widely recognised as "eco-terrorists".

So, according to the most reliable research, arson is probably a more likely cause of some of the fires across New South Wales than ardent global warming campaigners would like to admit.

But hard evidence defies the right-wing claims about the motive of arsonists.

Research indicates they are more likely to be sad, white men than over-zealous campaigners keen to get a fire going to ignite a crisis atmosphere about global warming.

In New South Wales. the typical arsonist is likely to be male and young, with the age of the average fire setter around 27, according to the Australian Institute of Criminology.

The researchers studied more than a thousand arsons of all types, including 133 deliberate bushfires. More than forty per cent of arsonists, both of bushfire and other fires, had previous convictions for violence, theft, drugs or arson offences. Sometimes it was a bunch of convictions for different crimes.

"There is also a relatively strong link with drug offences, with over 17 per cent of arsonists and around seven per cent of bushfire arsonists having at least one prior conviction for this offence," according to the researchers.

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Psychologist Dr Paul Read from Monash University said, "The mix of people lighting fires always follow the same age and gender profiles: whether accidental or deliberate, half are children, a minority elderly, and the most dangerous are those aged between 30 and 60. Ninety per cent are male."

He reckons there may be about 10,000 arsonists who "lurk from the top of Queensland to the southern-most tip of Victoria, but not all are active and some light fires during winter. The most dangerous light fires on the hottest days, generally closer to communities and during other blazes, suggesting more malicious motives."

The actual profile of arsonists is more ordinary. "At least among those caught, the profile emerges of an odd, unintelligent person from a chaotic family, marginalised at the fringes of society and deeply involved in many types of crime, not only fire."

Loners and losers, in common parlance.

There is no conflict between the idea that arsonists start many fires and that global warming makes it much easier for fires to start. There is no doubt that the fire season is getting longer and that temperatures are rising.

In other words, global warming makes it easier for arsonists to operate. Left and right should stop squabbling over it.