Assessing the Air Quality Impacts of Net-Zero GHG Emissions in Europe and Switzerland with ICON-ART

The European Union and the Swiss Federal Council have both set the ambitious goal of achieving net-zero greenhouse gas (GHG) emissions by 2050. While reducing fossil fuel use is widely assumed to improve air quality due to the co-emission of air pollutants during fossil fuel combustion, specific choices regarding alternative energy sources and changes in the building, industrial, and agricultural sectors may have very different and potentially detrimental impacts on air quality.

In this context, we study the air quality implications of transitioning to a net-zero GHG society in Europe and Switzerland by comparing two distinct scenarios for the year 2050: a net-zero pathway and a business-as-usual (BAU) scenario. The BAU scenario reflects the continuation of current energy policies without additional measures to achieve net-zero emissions. Comparing the BAU and net-zero scenarios allows us to assess how transformations in energy systems and associated changes in anthropogenic emissions shape the levels, composition, and dynamics of air pollutants.

Our analysis is based on simulations conducted with the state-of-the-art atmospheric chemistry and transport model ICON-ART. We have incorporated the latest MOZART tropospheric chemistry scheme to accurately represent key oxidation processes involving ozone, nitrogen oxides, and volatile organic compounds. ICON-ART also features advanced modules for aerosol dynamics, gas-aerosol interactions, and emissions from biogenic and natural sources. Emission inventories for the year 2050 are developed in alignment with Switzerland's energy strategy and European projections. Anthropogenic emissions of gas-phase species and particulate matter are integrated into ICON-ART using its online emission module.

Based on air quality simulations with ICON-ART, we will discuss the effects of reducing primary air pollutants on the formation of secondary air pollutants and the removal of air pollutants from the atmosphere, and show how Swiss and European air quality levels change as we move towards a net-zero society.