Pathways for including non-carbon dioxide aviation climate effects in the European Emission Trading System

Abstract

Aviation emissions are responsible for climate impacts through both carbon dioxide emissions andother emissions, in particular, of nitrogen oxides, water vapour, particulates, and contrail formation. InDecember 2022, the European Commission, Parliament and Council agreed to revise the EuropeanUnion Emission Trading System for aviation. As such, from January 1, 2025, aircraft operators mustmonitor non-carbon dioxide climate effects, but suitable metrics for climate impact, handling ofuncertainties and practical implementation are still under discussion or at least heavily debated. In thisperspective, we propose a procedure for how to include non-carbon dioxide aviation effects intopolitical frameworks. The main goal must be to create incentives for climate change mitigation for theaviation industry. Uncertainties in atmospheric processes need to be appropriately incorporated to minimise risk, and pilot projects are required to test implementation capabilities. Analysing risk,employing consistent monitoring, and determining economic effects will provide scientific grounds forincluding non-carbon dioxide effects in the European Union Emission Trading System.