Environmental Science and Engineering Seminar

Desert dust is the most ubiquitous atmospheric aerosol specie by mass, yet its impacts on human health and global climate remain highly uncertain. A key factor underlying this uncertainty is the large spread in climate model results of the amount of dust in the atmosphere and its size distribution. Here we use an integrative analysis of the size-resolved atmospheric dust loading to constrain dust effects on human health and global climate. Using a combination of observational, experimental, and model data, we find that atmospheric dust is more abundant and substantially coarser than represented in current climate models. We combine these constraints on the size-resolved global dust loading with epidemiological exposure-response functions to constrain the global mortality due to dust inhalation to 380 (220 – 600) thousand premature deaths per year. Furthermore, since coarse dust warms climate, the global dust direct radiative effect is likely to be less cooling than the ~-0.4 W/m² estimated by current models. Instead, we constrain the dust direct radiative effect to a range between -0.48 and +0.20 W/m², which includes the possibility that dust causes a net warming of the planet.