Potential effects of climate change on global air quality and human health

Climate change alters air quality and associated health outcomes. Climate-driven meteorological variables such as temperature, precipitation, and relative humidity influence transport, chemical transformation, and removal of air pollutants, particularly fine particulate matter (PM 2.5 ) and ozone (O 3 ). Here, we investigated the impacts of climate change on global PM 2.5 and O 3 concentrations via one-way coupling of an atmospheric chemical transport model (CTM) with the outputs of a general circulation model. We examined the impact on future air quality under three climate scenarios: SSP1–2.6, SSP2–4.5, and SSP5–8.5 of the Scenario Model Intercomparison Project (ScenarioMIP) for the mid-century (2040–2049) and the end of the century (2090–2099). To isolate the effect of climate change, anthropogenic and natural emissions were fixed at 2015 levels, enabling quantification of meteorologically driven changes in air quality and mortality. Our results show that climate forcing can trigger substantial regional variations in pollutant levels, with the global mean PM 2.5 concentration changing by –0.01 μg m -3 to –0.57 μg m -3 and the O 3 level from –0.05 ppbv to –1.20 ppbv. In our experimental framework–where primary and precursor emissions as well as chemical boundary conditions are held constant at 2015 levels–surface PM 2.5 and O 3 concentrations generally decline under future climate conditions due to meteorological shifts. These changes reflect the isolated effects of climate-driven meteorology rather than the combined climate-emission pathways associated with SSP-RCP scenarios. Although mean global pollutant changes appear to be modest, the associated health benefits are not negligible, corresponding to more than 0.2 million deaths avoided from PM 2.5 exposure, and 0.08 million deaths from O 3 exposure, when aggregated across all scenarios. Our results underscore the importance of considering climate–meteorology interactions when assessing future air quality and its public-health impacts. • Climate change impact on global air quality-related human health is non-negligible. • A novel GEOS-Chem framework driven by GCAP2.0 isolates meteorological impacts under multiple SSP-RCPs. • A wide range of meteorological shifts under future climate scenarios alter PM 2.5 and O 3 levels. • Climate-driven air quality changes result in substantial shifts in premature mortality.