Recently completing her PhD research, Natural Hazards Research Australia (the Centre) postgraduate scholar Dr Rebecca Ryan uncovered 3,000 years of fire history to help shape future fire management strategies.
The devastating 2019–20 Black Summer bushfires inspired Rebecca to dig deep into Australia’s past to better understand how bushfires have changed over thousands of years.
“We need a longer-term view of past fire patterns to improve how we predict and manage future events,” Rebecca said.
Bushfires have shaped the Australian landscape and biodiversity for millennia; however, as climate change continues to alter the fire regime, understanding how fire may change in the future proves critical for mitigation and prevention. Existing high-resolution records of past fire events are limited to the recent past or cannot accurately distinguish fire characteristics, such as severity and intensity.
Rebecca’s PhD research at the University of Wollongong could have a lasting impact on bushfire science by providing a new way to measure past fire severity and intensity, two characteristics that are hard to track in the long-term record. This data can strengthen fire predictive models and support better planning and preparation in bushfire-prone areas.
To uncover the past, Rebecca developed two new techniques:
- using boron isotopes to detect the severity of a fire (for example, whether it reached the forest canopy or remained confined to the understory)
- using FTIR Spectroscopy to determine changes in chemical bonds to reveal how intense (determined by temperature and heating duration) the fire was.
She applied these methods to sediment samples from the Blue Mountains and Namadgi National Park.
What Rebecca found was striking: bushfires in southeastern Australia have become more intense and more frequent over the past 200 years compared to the previous 3000. This shift appears to be driven by changes in climate, vegetation (particularly fire-prone eucalypts) and human activity.
As part of her PhD supported by the Centre, Rebecca shared her findings with experts and emergency services through the Natural Hazards Research Forum and Hazardous Webinars.
“Having access to feedback from both researchers and people working on the ground has helped shape my research and its real-world relevance,” she said.
Rebecca’s research provides valuable insights into global fire science and could inform management strategies not only in Australia but also in other fire-affected regions around the world.