Trends in fire activity and associated fire-induced soil-dust emissions over the last two decades

Vegetation fires emit a wide variety of aerosol particles. Most originate from the combustion of carbonaceous material, however, fire-induced pyro-convective updrafts can modify the near-surface wind field in a way that mobilizes soil-dust particles from the ground and inject them into the atmosphere. Mineral dust particles are well known as efficient cloud condensation nuclei (CCN) and ice nucleating particles (INPs), thereby substantially altering cloud microphysics and influencing the Earth’s radiation budget through scattering and absorption of solar radiation. When emitted during wildfires, these dust particles are likely mixed with smoke aerosols, which modifies their physio-chemical properties and consequently their impacts on the atmosphere and climate. Therefore, a precise characterization of this emission pathway and robust knowledge of its global abundance are essential.

The fire-driven emission of soil-dust particles has already been incorporated into the global aerosol–climate model ICON-HAM through the development of a sophisticated parameterization that describes fire-induced dust emission fluxes as a function of fire intensity and some soil-surface properties, such as the soil type and the vegetation class at the fire location. Multi-year model simulations have indicated that fire-related dust emissions can account for a significant fraction of the global atmospheric dust load, exhibiting strong regional and seasonal variability driven by a varying fire activity and the local soil-surface conditions.

However, global fire activity has changed substantially over the recent decades due to both climatic and socioeconomic factors, resulting in significant shifts in the magnitude and regional distribution of fire-related dust emissions. Here, trends in fire-induced dust emissions over the past 20 years are analyzed and changes across different continental regions are contrasted. Furthermore, projections of fire activity under future climate scenarios can be used to assess the strength and regional distribution of fire-related dust emissions under changing climate conditions and mitigation strategies. This analysis can contribute to improved estimates of the future global aerosol burden, in particular with respect to the changing fire occurrence in a warmer world.