There are, on average, 62,000 fires in Australia every year. Only a very small number strike far from populated areas and satellite studies tell us that lightning is responsible for only 13 per cent. Not so the current fires threatening to engulf Queensland and NSW. There were no lightning strikes on most of the days when the fires first started in September. Although there have been since, these fires – joining up to create a new form of mega-fire – are almost all man-made.

About 40 per cent of fires are deliberately lit ... The Hillville fire that destroyed homes last week. Credit:Nick Moir

A 2015 satellite analysis of 113,000 fires from 1997-2009 confirmed what we had known for some time – 40 per cent of fires are deliberately lit, another 47 per cent accidental. This generally matches previous data published a decade earlier that about half of all fires were suspected or deliberate arson, and 37 per cent accidental. Combined, they reach the same conclusion: 87 per cent are man-made.

The cycles of the seasons are changing beyond that which can be explained by known forces, both ancient and modern. Every lethal wildfire since 1857 has happened at the height of summer. Until now. The size of these fires has never been seen in Australia's history this side of summer, and certainly not starting as early as September.

Seasonal changes, in part due to climate change on top of natural oscillations causing the drought and westerly winds, have some origins in man-made emissions. More directly, however, the source of ignition is human.