Highly anomalous fire emissions from the 2019–2020 Australian bushfires

Abstract

While it is widely recognized that extreme fires have been increasing under warming and drying climate, knowledge regarding the magnitude and intensity of extreme fires is very limited. Moreover, fire emissions reported by existing emissions inventories show large discrepancies due to different approaches and parameters. In this study, we analyzed the fire intensity and emissions magnitude of the 2019–2020 Australian bushfires using fire observations from multiple satellites. The results show that the bushfires were extreme in both their number and intensity, which were higher by a factor of 25 and 19, respectively, compared to the past two-decade seasonal mean. The 2019-2020 bushfires burned a total of 112.3 Tg biomass and released 178.6 ± 13.6 Tg CO2 (carbon dioxide), 1.71 ± 1.28 Tg PM2.5 (particulate matter with a diameter < 2.5 μm), and 0.061 ± 0.04 Tg BC (black carbon) across eastern and southern Australia. The CO2 emissions are 35% of Australia's greenhouse emissions from all sectors combined in 2020. Furthermore, the extreme fires in the most severe day and hour released 10% and 1.4% of the entire seasonal emissions, respectively. Our findings provide quantitative information for investigating the impacts of smoke emissions on air quality, ecosystem, and climate.