European air quality in the 2030s and 2050s: Impacts of global and regional emission trends and of climate change

A chemistry-transport model using two-way nested regional (Europe) and global domains is used to evaluate the effects of climate and emission changes on air quality over Europe for the 2030s and 2050s, by comparison with the emissions and climate of the recent past. We investigated the pollutant levels under the implementations of reduced anthropogenic emissions (NOx, SO2, etc) over Europe and, at the global scale, under the Representative Concentrations Pathways (RCP8.5) scenario produced by the Fifth Assessment Report (AR5) of IPCC. The simulations show an increase in surface ozone in northwestern Europe and a decrease in southern areas in the future horizons studied here. Over Europe, average O3 levels steadily increase with a rate of around 3 μg m−3 per decade in summer. For this pollutant, the contributions of long range transport over the Northern Hemisphere and climate changes have been assessed and appear to counterbalance and even slightly outweigh the effects of European reductions in precursors' anthropogenic emissions. The tropospheric ozone budget is found to be dominated by enhanced stratosphere-troposphere exchanges in future climate while the chemical budget is significantly reduced. Our results show that a NOx-limited chemical regime will stretch over most of Europe, including especially Western France in the future. These findings allow supporting efficient future precursor emissions abatement strategies in order to limit O3 pollution and maintain or improve air quality standards in Europe.