Causes and consequences of eastern Australia's 2019-20 season of mega-fires

The 2019–20 fire season in eastern Australia is attracting considerable national and international attention. At the time of writing c. 3.8 million ha of mainly temperate forest have burnt in the state of New South Wales (NSW; NSW Rural Fire Service, 29/12/2019; Figure 1a). Major blazes are also occurring in other states, including over 0.5 million ha in the state of Victoria (situated on the southern border of NSW). This exceeds the area burnt in the 1939 Black Friday fires (c. 2 million ha), which were the largest fires recorded in temperate Australian forests since European settlement (www.ffm.vic.gov.au). Notably, the Gospers Mountain fire on the fringes of Sydney is over 508,000 ha (as of 29/12/2019; Figure 1a), and is still uncontained, having traversed the width of the Blue Mountains World Heritage Area and now merged with other fires near the coast. It is important to note that this record-breaking fire season is not yet over, with the south-eastern Australian fire season typically extending to the end of summer (February). Multiple large fires are still burning across NSW and in other states, with the situation rapidly changing.