Aviation NOx emissions and their increasing impact on global surface air quality

Although the impacts of aviation NOx on local air quality are well-researched, the effects on climate and global air quality are disputed. With the aviation sector under pressure to reduce its contributions to climate change, some studies have suggested that fuel efficiency be prioritized over reductions in aviation NOx emissions. As a result, while emissions of NOx have declined rapidly in other sectors, the amount of NOx emitted per kilogram of aviation fuel burned is estimated to have increased by 17% between 1990 and 2018 with corresponding - and continuing - growth in environmental impact. We use a global atmospheric chemistry-transport model to simulate, at high resolution, the global air quality impacts of aviation, finding that emissions of cruise altitude NOx specifically are associated with the majority of aviation's air quality impacts. Contrary to prior work we find that global simulation at high resolution (~50 km) results in an increase in the simulated impacts relative to simulations at low resolution (~400 km), and that - subject to the choice of epidemiological data source - aviation-attributable ozone may be responsible for global health impacts comparable in magnitude to the total national health burden of US combustion emissions. This presentation will explore the atmospheric mechanisms behind these effects, degree to which model resolution does or does not affect the simulated impacts, the implications for future aviation NOx regulation, and the dominant sources of uncertainty in the result.