The turbulent future brings a breath of fresh air

Ventilation of health hazardous aerosol pollution within the planetary boundary layer (PBL) is dependent upon turbulent mixing, which is closely linked to PBL height. We show that emissions of both CO₂ and absorbing aerosols such as black carbon (BC) influence the number of severe air pollution episodes through impacts on turbulence and PBL height. While absorbing aerosols cause increased boundary layer stability and reduced turbulence through atmospheric heating, CO₂ has the opposite effect over land through surface warming. In future scenarios with increasing CO₂ concentrations and reduced aerosol emissions, around 10% of the world’s population currently living in regions with high pollution levels are likely to experience a particularly strong increase in turbulence and PBL height. Our results highlight boundary layer processes and the added positive impact of black carbon mitigation on human health.

Camilla W. Stjern, Øivind Hodnebrog, Gunnar Myhre, Ignacio Pisso