Jamie Morton is the NZ Herald's science reporter.

New $8.5m study to grapple with 'extreme fire'

Scientists expect the number of rural fires in New Zealand will double - or even triple - by the end of the century. Photo: File
Scientists expect the number of rural fires in New Zealand will double - or even triple - by the end of the century. Photo: File

They call it "extreme fire" - a fast-moving mass of heat and flames spewing burning embers and behaving in ways that firefighters can't predict.

Understanding how these wild beasts act is now the focus of an $8.5 million study that could lead to the development of fire-fighting robots or technology that can accurately predict how fire will spread over different landscapes.

Grant Pearce, a senior fire scientist at Crown research institute Scion, said cases of extreme fire behaviour had already been seen in some smaller blazes and in conditions where it wasn't expected, including a fire that devastated 90ha near Hanmer Springs in March.

"We are getting more of this extreme fire behaviour, which means that not only are the fires bigger and more intense with larger flames, but they're more likely to exhibit extreme fire characteristics."

These included spotting, where embers and other particles are hurled ahead of the fire front, fire tornadoes and whirls, and "blow-up" conditions, where the inferno suddenly escalated in size and intensity.

Pearce said these unpredictable and dynamic conditions put firefighters at greater risk, particularly if the fire spread behind them.

Although rural fires in New Zealand wreaked enough damage to cost the economy around $67 million each year, they generally tended to be smaller, and not on the scale of monster blazes seen in dry places like Australia that roll through thousands of hectares of land.

"But with this more extreme fire behaviour, those smaller fires will be more difficult to put out."

Scion senior fire scientist Grant Pearce (right) monitors an experimental burn. Photo: Supplied
Scion senior fire scientist Grant Pearce (right) monitors an experimental burn. Photo: Supplied


Further, under projected climate change scenarios - projected to deliver several degrees of average temperature increase and stronger, more frequent westerly winds - it's expected that the number of extreme fires will double or treble by the end of the century, or perhaps even by 2050.

But that was just one part of the picture, Pearce said.

Population growth, more people moving to rural areas, and a changing landscape bringing different fuel sources, such as wilding pines, would also add to the threat.

"We've always been a maritime climate surrounded by the oceans, which means conditions are cooler and more moist, but we are warming up and getting drier in some places, with windier conditions as well."

Conditions that increased extreme fire risk included mid to high temperatures, low humidity and wind speeds gusting at 50 to 70km/h.

As part of the new five year study, to be led by Scion, Pearce and his colleagues will test theories around the mechanisms that cause heat transfer and contribute to turbulence at flame fronts.

Scion senior fire scientist Grant Pearce
Scion senior fire scientist Grant Pearce


It also sought to improve existing prediction tools with technology that could simulate fire spread based on real-time monitoring, satellite detection of fires, and new methods for suppressing the blazes once they started.

"We're barely even scratching the surface at the moment; we are thinking, can we use robots instead of firefighters, or can we find ways of creating fire breaks using mechanical equipment that might be remotely controlled."

The research, bringing together fire scientists from around the world, would trial these new prototype tools in experimental burns.

Head of the National Rural Fire Authority, Kevin O'Connor, called the study "a great investment".

"Any advances we can make in terms of understanding fire behaviour are hugely beneficial in reducing damage to property and potentially saving lives."

The project is supported by the Ministry of Business, Innovation and Employment's Endeavour Fund, which this year awarded researchers $209m over five years.

- NZ Herald

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