The carbon cycle of southeast Australia during 2019-2020: Drought, fires and subsequent recovery

2019 was the hottest and driest year on record for southeast Australia leading to bushfires of unprecedented extent between November 2019 and January 2020. In this study, we utilize space-based measurements of trace gases (TROPOspheric Monitoring Instrument XCO, Orbiting Carbon Observatory 2 XCO2) and up-scaled GPP (FluxSat GPP) to quantify the carbon cycle anomalies resulting from drought and fire in southeast Australia during the 2019-2020 growing season. We find that biomass burning emissions released 113-236 TgC of CO2 while drought and fire induced anomalies in net ecosystem exchange reduced growing season carbon uptake by an additional 19-52 TgC of CO2. These carbon losses were concentrated during the spring and early summer, when hot-dry conditions were most severe. A shift to cooler conditions and above average rainfall during February is found to result in a partial recovery and greening in unburned ecosystems. However, fire impacted areas had continued suppressed productivity for the remainder of the growing season. This study showcases the capability of combining observations from multiple satellites to monitor the carbon and ecosystem anomalies resulting from extreme events.