The role of wildfire emissions on extreme fire weather during Australia’s Black Summer through smoke-weather feedbacks

Abstract Background The bidirectional coupling between wildfires and Earth systems is increasingly evident, but prevailing fire risk models, such as the Canadian Fire Weather Index (FWI) and the McArthur Forest Fire Danger Index (FFDI), often neglect the role of fire emission-mediated climate interactions. Here, we employ a coupled atmospheric-chemistry model (WRF-Chem, v4.3) to quantify the modulation of fire weather indices by pyrogenic aerosols during the catastrophic 2019–2020 Australian fire season. Results Results show black carbon (BC) and organic carbon (OC) reduced extreme FWI (> 60) in central Australia while increasing moderate FWI (20–40). Conversely, aerosols elevated extreme FFDI (> 50) probabilities in southeastern fire-prone regions through BC-induced warming and OC-mediated drying. Sensitivity tests revealed BC removal increased FFDI in arid areas by reducing cloud stabilization, while OC removal enhanced FFDI in vegetated zones by suppressing rainfall. This work found the spatial mismatch between fire indices and actual activity, with fuel availability being the critical factor. High FFDI in fuel-scarce central Australia produced few fires, while moderate indices in fuel-rich eastern regions coincided with intense burning. This demonstrates how static fuel-moisture assumptions in current models underestimate meteorological impacts. Conclusions Our findings underscore the importance of incorporating dynamic aerosol feedbacks in fire models. Coupled fire-atmosphere models like WRF-Chem are essential for accurate predictions, particularly in regions vulnerable to fire-climate feedbacks. Future research should improve fire emission interaction modeling and expand global analyses under climate change scenarios to better address escalating wildfire risks.