It happens in a heartbeat: a small bushfire becomes an inferno, suddenly devouring everything in its path: humans, houses, livestock and pasture, habitat and native wildlife. In minutes, the firefighters’ battle becomes not just hopeless, but treacherous.
The dynamics of that moment – when a manageable blaze becomes a destructive beast – fascinate and drive Professor Jason Sharples. A bushfire scientist and leader of UNSW’s Bushfire Research Group in Canberra, his pioneering work over two decades has revealed how extreme fires grow, spread and move, particularly in ways that have previously confounded experts.
Combining physics and mathematics with new technologies, Sharples tackles the fires we don’t understand, finding ways to explain their behaviour and help predict where and when they might occur. His work is changing approaches to bushfire prevention and management, urban planning and firefighter training, and his expert voice helped shape recommendations made by the NSW Government inquiry into the devastating bushfires of 2019 – 20.
But Sharples’ interest in fire dynamics is personal as well as academic. A volunteer in the ACT Rural Fire Service for two decades, he has felt the scorching heat through his protective suit and seen first-hand how a gentle breeze on embers can ignite the forest. With dedicated volunteers, he has knocked on doors to warn homeowners about the risk to their property and lives: a risk science doesn’t yet fully comprehend.
“For me, it’s important to focus on these fires we don’t understand. They are the real culprits, doing the lion’s share of the damage,” says Sharples.
Using maths to understand the world
His natural curiosity was fueled, as a child, by nature and technology: he roamed the wetlands behind the family home at Lake Macquarie in NSW, and took apart old machines his father, a television technician, brought home from work.
But it was Newton’s second law of motion – F = ma – that ignited Sharples’ interest in science and mathematics in high school. “I was half paying attention in science, but I remember thinking: ‘Hang on a minute! You’re saying that an equation can actually tell me what’s going to happen in the real world?’
“It was the first big epiphany – that there was this link between a mathematical equation and physical reality, that you could use mathematics to understand the world and even predict what it might do. I was fascinated and thought: I need to understand this.”
He told his careers advisor that he’d like to be a doctor, but she set him straight: his maths wasn’t good enough for medicine. It was the “kick up the bum” he needed to take study seriously, and after school he pursued an interest in chemistry before settling on physics and mathematics.
“My PhD, in Canberra, was in general relativity – mathematical relativity, black hole physics, essentially. But I had got into an area that was very niche, and I became concerned that I might have rendered myself unemployable,” he laughs. “As it turns out, that view was completely wrong, but I just started applying for every job that I could find, from hedge fund analyst to Bureau of Meteorology forecaster – I applied for them all!”
Sharples’ first job, analysing climate data at ANU’s Centre for Resource and Environmental Studies, combined his environmental interest with his talent for mathematical analysis and predictive modelling. “I had thought I was unemployable because I’d followed mathematics so deeply down a particular niche, but the lesson I learned was that it had actually given me the skills to move wherever I wanted in science.”
Volunteer firefighting
In 2003 Sharples was investigating rainfall when Canberra was devastated by its worst bushfire disaster, with four lives and 500 homes lost. Federal research funding became available through the Bushfire Cooperative Research Centre’s HighFire project, so he signed on as a volunteer firefighter, before moving into bushfire research.
“Even before I started as a volunteer, I was interested in what sort of science was underpinning fire management decisions,” he recalls. “I was surprised to learn how primitive some of the modelling techniques were. It’s not to take anything away from the people who developed these models, but to a mathematician there seemed to be a lot of room for development.”
“The existing models were also somewhat limited, having mostly been trained on fires we understand – essentially fairly small, and with not too many interesting dynamics going. But they’re not the fires that tend to burn houses and kill people and animals.”
To shed light on these catastrophic fires, Sharples tapped into emerging data sources like thermal imaging, which provided precise detail about a fire’s evolution and enabled him to identify an unusual dynamic: fires are expected to travel with the wind, but sometimes they defy expectations, traveling perpendicular to the wind, spreading quickly and broadly, raining down deadly embers.
Since its discovery in 2006, this important fire dynamic, known as vorticity-driven lateral spread (VLS), has been identified as a culprit in the development of many extreme fires and can lead to “deep flaming”, which spreads rapidly and broadly, increasing the chance of firestorms – intense blazes with plumes that develop thunderstorm characteristics.
Sharples has since studied other fire dynamics and, using complex mathematical modeling, to pinpoint geographic features and weather conditions more likely to generate an extreme fire. In 2021, his team completed a spatial map system for Australian fire agencies, funded through the Bushfire and Natural Hazards Cooperative Research Centre, that identifies parts of landscape more likely to generate extreme fire behavior through VLS. He has teamed up with international experts and is involved in a diverse range of projects aimed at predicting – and preventing – extreme fires, which will become more prevalent because of climate change.
His research has informed government policy and The NSW Rural Fire Service has adopted his group’s discoveries as part of standard protocols for fire behaviour analysis and they’ve been incorporated in firefighter training modules by the Australasian Fire and Emergency Service Authorities Council (AFAC), which manages national firefighting curricula.
“Being in a brigade, you get to know the good people who give up their time,” Sharples says. “I feel like they deserve the best science underpinning their safety. It’s another motivation: every time you hear about a firefighter getting injured or killed, it’s a kick to the guts and you wonder, ‘Is there something I could have done to prevent that?’”
The aftermath of a catastrophic blaze, Sharples reflects, usually produces a chorus of strident voices keen to apportion blame, and he agrees that for complex reasons, fire has been politicised. Climate change, land management strategies, fuel reduction measures and urban creep are hotly debated, but he is interested in evidence, not opinion.
“That’s the power of science, right? You can check if something works – or not – by looking, which is what we do.”
A Bundjalung man, he is supportive of Indigenous cultural burning practices, but acknowledged that these, too, may have limits in a world affected by rising temperatures.
“What the Old People did for millennia was in different country to what it is now, and a different climate. I still don’t know if the advantages you get from cultural burning are going to be enough to overcome the extra risks we’re dealing with now.”
Both as a firefighter and scientist, Sharples feels the need to keep bushfire risks and preparation prominent in community consciousness. He is concerned that a relatively calm summer in 2021-22 – in Australia at least – and global preoccupation with COVID-19 could cause complacency.
“I think a lot of people have that black summer of 2019-20 etched into their souls. Many probably dodged a bullet, and might not be so lucky next time,” Sharples reflects. “In those communities, you would hope that they get the message from what other people have suffered, that they shouldn’t be complacent. But it’s tricky. Until you go through one of these events, it’s hard to appreciate what they are.”
Article by Michelle Fincke