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As flames engulf the bush, a wave of heat washes over the onlookers and glowing ash showers the lab.
High above, where the flames flicker at the ceiling, a giant rangehood sucks up all the smoke and funnels it into instruments that analyse gases.
This bonfire isn't just for fun. It's for science.
Playing with fire in the lab
The fire engineering lab at the University of Canterbury is a special facility where scientists can set things on fire and study how they burn.
The high-tech instruments collect data on the gases emitted, the amount of energy released, and the temperature of the flames.
Five or six couches are burned here every year, part of an assignment for fire engineering students, says Dr Andres Valencia. This is because couches are a common household item with fabric and foam that can make them especially dangerous in a fire.
They have also recreated smoke explosions and fire tornadoes in the lab. The latter are whirlwinds of hot air, flames and ash that are generated in big wildfires.
Gorse part of the burning agenda
On the burner today is a large clump of gorse, a prickly plant that has invaded large swathes of New Zealand's landscape. It's also quite prone to burning.
PhD researcher and fire-fighter Kate Melnick collected this gorse from just outside Christchurch. She's investigating how all the different characteristics of the plant affect its flammability - for example, how much moisture it contains, and how fine its leaves and twigs are.
Dr Andres Valencia, Kate Melnick and Fearghal Gill are investigating the science of wildfires at the University of Canterbury. Photo: Ellen Rykers / RNZ
So far, she's discovered that dead gorse and live gorse burn very differently, even if they have the same moisture levels.
"The live material actually burned more vigourously and at a higher intensity. But it took longer to ignite," she explains.
"So if a fire were to spark, the dead material will probably ignite first. However, once the flame passes over to the live material, then you get even higher intensity."
New Zealand's increasing wildfire risk
The ultimate aim is to enhance our ability to predict and prepare for wildfires. Kate's work contributes to a programme of fire research led by Andres that is investigating fire from all angles: from gorse to grass, to the effects of wind, to impacts on people and infrastructure.
PhD researcher Kate Melnick at the University of Canterbury fire engineering lab, a purpose-built facility for setting things on fire and studying how they burn. Photo: Ellen Rykers / RNZ
New Zealand experiences around 4500 wildfires every year - a number that has grown over the past two decades.
In some places, the wildfire risk is increasing, as climate change leads to higher temperatures, stronger winds and lower rainfall. As urban areas expand, more people are shifting into wildfire-prone areas too.
"If you compare the risk of wildfires in New Zealand with Australia or California or Canada, I will say it is low," says Andres. "However, what I think is happening right now is that we are seeing an increase of wildfires happening close to the cities.
"So, our approach is more: we see the future and we think that we can prepare for it, rather than let's try to find solutions as it happens."
Listen to the episode to learn more about the fire research underway and hear about Kate's experiences as a wildland fire-fighter in Canada.
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