Konstantina Paraskevopoulou

Wildfires are an underexplored component of the Earth system that can alter atmospheric chemistry and climate by emitting greenhouse gases and aerosols. Biomass burning (BB) emissions perturb tropospheric chemistry by releasing ozone precursors and reactive nitrogen, degrading air quality and enhancing regional radiative forcing. This study investigates the effects of interannual variability (IAV) in BB emissions on short-lived tropospheric constituents, namely aerosols, CO, O₃ and NO₂, through global chemistry transport model (CTM) experiments spanning 1997–2015, a period encompassing strong El Niño–Southern Oscillation (ENSO) events and associated major wildfires. BB emissions were derived from the Global Fire Emissions Database version 5 (GFED5), which better represents the atmospheric impacts of major wildfire events than its predecessors. Using the Tracer Model 5 Massively Parallel (TM5-MP) CTM, we conducted three simulations: a base scenario with interannually varying emissions, a mean scenario retaining the seasonal cycle but removing IAV, and a zero scenario with BB emissions nullified. We find that BB IAV contributes substantially to CO IAV in all regions, whereas O₃ is influenced much less, except in regions directly affected by ENSO. BB is associated with aerosol variability over boreal and tropical burning regions and contributes to NO₂ variability outside industrialised regions.

Our study focuses on investigating the present-day influence of wildfires on the global atmosphere. To achieve this, we utilized four observational biomass burning (BB) emissions datasets for present-day simulations employing the TM5 Chemical Transport Model (CTM). To assess how different emissions estimates influence the model’s ability to simulate the atmosphere, we compared the following datasets over the period 2003–2015: GFED4s, GFASv1.2, FEERv1.0-G1.2 and QFEDv2.6r1. Our study aims to investigate the role of wildfires in affecting important trace gases and aerosols. Their impact on atmospheric composition and their interactions with solar radiation affect the radiative balance at the Earth’s surface and, consequently, temperature trends in the troposphere.