Bringing to life a monitoring, reporting and verification system for aviation non-CO2 climate effects

To date, only CO2 is addressed in the EU aviation Emission Trading System (EU-ETS), which implies that the major part of aviation climate effects, the non-CO2 effects, is not included. An agreement on a revision of the CO2 EU-ETS by the EU trilogue from 2022 now includes monitoring, reporting and verification (MRV) of non-CO2 aviation climate effects starting in 2025. However, the detailed steps towards an inclusion of non-CO2 effects are controversially debated for i) the calculation of aviation CO2 equivalents (CO2e), regarding suitable models as well as the choice of a climate metric and its time horizon, ii) the complexity of the entire system including data requirements, availability and streams generating administrative burden for various parties and iii) the large uncertainties in non-CO2 climate effects and their associated risks. Here, we discuss, analyse and put forward these points aiming at an inclusion of aviation non-CO2 effects into a political framework, as results of a project with the German Environmental Agency and current activities at EU-commision level as part of a EU-tender. In this presentation, we lay out a plan for an MRV system including tasks for monitoring and reporting by aircraft operators as well as verifying by competent autorities. Our work aims at supporting the process towards an EU-wide MRV system and its way to operationalisation. This includes analysis of suitable climate metrics and climate models for CO2e calculations of non-CO2 emissions by aviation. Moreover, the data needed to apply the models for CO2e computation of individual flights is defined. For this, a minimum set of data and a possible extended list of data for both a climatological and a weather-based approach is determined. The more complex solutions can be used to on the one hand increase accuracy of the results and on the other hand allow more incentives for aircraft operators to mitigate climate effects. However, increases in administrative burden have to be considered to maintain acceptance by all parties. Advice on default values for data gaps is provided too, which is needed in case of individually or generally missing data for example due to technical issues or confidentiality. Lastly, uncertainties in the context of non-CO2 aviation effects and their associated risks for the MRV are discussed. The governing overarching goal in this undertaking must always remain the contribution to reaching the Paris Agreement targets through climate change mitigation incentives for the aviation industry.