Impact of the 2019-20 Mega-Fires on the Greater Blue Mountains World Heritage Area, New South Wales

The 2019-20 'Black Summer' mega-fires burnt an unprecedented 79% of the Greater Blue Mountains World Heritage Area, which is more than three times greater than the area burnt in any of the previous 48 fire seasons. The fires were not proportionally more severe than previous large fires but their huge scale meant that an unprecedented 29% of the World Heritage Area was burnt at high to extreme severity. The fires were particularly extensive and severe in parts of the World Heritage Area that are rarely burnt by wildfires, notably in cooler areas over 1000 m in the south-west. The vegetation type least impacted by the fires was grassy woodland, an important bird habitat, of which 48% was burnt. However, grassy woodland covers less than 2% of the World Heritage Area and extensive areas of grassy woodland were burnt elsewhere in 2019-20. Rainforest and shrubby wet sclerophyll forest in sheltered gullies have played an important role in past fires as unburnt fauna refuges but were unusually heavily impacted in 2019-20, with 82% and 79% burnt, respectively. The fauna and flora of the World Heritage area are likely to eventually recover from the Black Summer fires if this was an exceptional event that will not recur for many decades. However, a change in the Australian fire regime to more frequent, more extensive, more severe wildfires as a result of climate change has long been predicted. If the Black Summer fires are a harbinger of this change, the long-term impact on the environment and biota of the World Heritage Area would be catastrophic.