Dozens of bushfires surged across New South Wales (NSW) and Tasmania over the weekend, resulting in devastating losses and significant destruction. Tragically, a firefighter lost his life while battling the flames. In NSW, the town of Koolewong saw 16 homes destroyed, alongside four homes in Bulahdelah, and another 19 properties lost in Tasmania’s Dolphin Sands. Temperatures soared to 41°C in Koolewong, while strong winds exacerbated the situation, making firefighting efforts increasingly challenging.
The rapid escalation of these fires caught many off guard, raising concerns about the underlying causes. Since the megafires of the 2019-20 summer, Australia has experienced several wet years, allowing vegetation to regrow robustly. However, below-average rainfall in recent months has dried out landscapes, creating highly flammable conditions. Prime Minister Anthony Albanese has acknowledged the situation, warning that this fire season could be particularly difficult.
Understanding the Fire Risks
The current bushfires highlight the critical role that environmental conditions play in fire behaviour. While the presence of dry fuel is a significant factor, the weather also greatly influences fire risk. Fires require fuel to ignite, which scientists categorize into “dead” and “live” fuels. Dead fuels consist of fallen leaves and twigs, while live fuels include the foliage from living plants. When conditions are wet, these fuels do not ignite easily, but during periods of extreme heat and low humidity, drying occurs rapidly.
Data from recent calculations indicated that moisture levels in dead fuels dropped to dangerously low levels, falling below 7% in both Koolewong and Bulahdelah on December 6, 2023. This critical threshold heightens the risk of fire spread. Low moisture combined with strong winds significantly increases the likelihood of intense fires.
The impact of these fires was notably severe in Koolewong, located just south of Gosford on the Central Coast. The area’s steep terrain and limited access hampered firefighting efforts. Many homes were situated near eucalypt forests, which can enhance the risk of destruction. Research indicates that homes in regions where forests dominate more than 60% of the surrounding area face a higher likelihood of being destroyed by fire, particularly if built before modern bushfire-resistant construction standards were established.
Previous Fires and Future Outlook
The current fires are burning through forests that narrowly escaped the catastrophic 2019-20 Black Summer fires, which devastated over 7.2 million hectares across southern Australia. Following those megafires, NSW experienced a reprieve, with several years of wetter-than-average conditions, except for 2023. While bushfires can reduce fuel loads and lower the risk in subsequent years, this summer marks six years since the Black Summer, allowing fuel levels to recover significantly.
Conditions are ripe for intense fires due to a combination of factors. Wet years have led to an increase in midstorey fuels—flammable shrubs and regenerating eucalypts—which can escalate fire intensity. These fuels create a “ladder” effect, allowing flames from the ground to reach higher into the forest canopy.
Drought conditions have eased for much of southern Australia, but eastern NSW still faces challenges. The Bureau of Meteorology has reported a weak La Niña event, which typically brings wetter weather. However, this particular event seems less impactful, and forecasts suggest that rainfall may be lower than average for December.
With these intense fires and the prevailing dry conditions, caution is paramount this fire season, especially in drought-affected eastern NSW. The threat posed by bushfires remains pressing, requiring vigilance and preparedness in communities across the region.
