F1: Area burnt in prescribed burns and bushfires

Bushfires

In 2020, nearly 90,000 hectares, around 40% of the ACT, were burnt by bushfires (Figures 1 and 2). The fires threatened the township of Tharwa and the southern suburbs of Canberra, with residents warned to be ready to evacuate. Fortunately, there was no loss of human life or residential buildings. The ACT’s 2020 bushfires were the largest and most severe since the devastating fires of 2003 burnt 164,000 hectares, 70% of the ACT.

The most significant 2020 bushfire in the ACT was the Orroral Valley fire (Figure 3) which burnt around 80% of Namadgi National Park (82,700 hectares) and 22% (1,450 hectares) of Tidbinbilla Nature Reserve. The fire started on Monday 27 January 2020, ignited by the landing light of an Australian Army helicopter which had set down in grassland in the Namadgi National Park. The spread and severity of the fire was driven by elevated fire danger conditions (including two catastrophic and two severe fire danger days in the days and weeks leading to the Orroral Valley fire — see Indicator F2: Fire risk), topography, and the exceptionally dry fuel loads. The fire was contained at around 88,000 hectares thanks to the efforts of fire suppression activities and rainfall across the fireground between 10 and 14 February. The Orroral Valley fire was declared extinguished on 27 February 2020.

The environmental impact of the Orroral Valley fire is especially concerning because much of Namadgi National Park and the Tidbinbilla Nature Reserve were also burnt in the 2003 fires (Figure 4). Within the ACT, around 75,000 hectares burnt by the 2003 fire were re-burnt in 2020. As a result, large areas of the ACT’s natural environment have now experienced severe and widespread burning twice in just 17 years. This will affect native vegetation, biodiversity and ecosystem health for decades to come (see 4. Bushfires in the ACT; Biodiversity; Indicator B4: Extent and condition of native vegetation; Water; and Land).

Prior to the 2003 fires, a large fire also occurred in Namadgi National Park in January 1983 burning around 34,700 hectares. Nearly all the area burnt by the 1983 fires was burnt again in 2003, and again in 2020 (Figure 5). This means that a large area of Namadgi National Park has been burnt three times in 37 years.

The Orroral Valley Bushfire also damaged and destroyed many cultural heritage sites and smoke from bushfires in NSW and the ACT severely impacted Canberra’s air quality over the 2019–20 summer period (see 4. Bushfires in the ACT and Air).

In addition to the Orroral Valley bushfire, the Beard bushfire burnt around 424 hectares. The fire started on Wednesday 22 January 2020 in the Pialligo Redwood Park and threatened properties in Beard, Oaks Estate and West Queanbeyan. The fire was brought under control on 23 January and declared out at on Tuesday 28 January 2020.

For years between the 2003 and 2020, the annual area burnt by bushfires was mostly under 100 hectares except for 591 hectares in 2004, 1,474 hectares in 2006, and 443 hectares in 2018. There were only five hectares of bushfires in 2021 and 2022. This shows that the ACT generally experiences small bushfires in most years. However, the 2003 and 2020 bushfires demonstrate the significant risk of large and severe bushfires in the ACT when conditions are favourable for the occurrence and spread of fire.

Prescribed burning

For years between the 2003 and 2020 bushfires, the area subject to prescribed burning far exceeded that of bushfires, accounting for 93% of the 45,000 hectares burnt between 2004 and 2019 (Figures 1 and 2).

For the period 2020 to 2022, only 347 hectares were burnt in prescribed fires. This is much lower than for most years and is the result of the wetter conditions and the extensive burn area of the 2020 bushfires. The low area of prescribed burns is similar to other wet years including 2011 and 2012.

The vast majority of prescribed burns in the ACT are undertaken for fuel reduction purposes (Figure 6). Between 2009 and 2022, fuel reduction burns accounted for over 98% (around 31,700 hectares) of all prescribed burns in the ACT.

Ecological burns have increased in the ACT since 2016, demonstrating the ACT’s growing recognition of the importance of fire for vegetation, biodiversity and cultural management (Figure 7).

Causes of bushfires

Between 2004 and 2022, there were 113 non-prescribed burn ignitions in the ACT. Arson accounted for 43% of these ignitions and remains the main cause of fires in the ACT (Figure 8). Lightning caused 16% of ignitions and 13% were caused by accidents. These results show that most fires in the ACT are deliberately lit. For many fires, the cause cannot be ascertained with unknown ignition source fires accounting for 28% of the total fires recorded between 2004 and 2022.