Integration of non-CO2 effects of aviation in the EU ETS and under CORSIA : final report

In addition to carbon dioxide, air traffic operation affects the climate through other emissions and atmospheric processes, such as the formation of ozone and contrail cirrus. The climate impact of these non-CO2 effects is strongly dependent on the emission location (in particular cruise altitude) and emission time (e.g. weather conditions) and, thus, highly non-linear to the fuel consumption. Although non-CO2 effects are responsible for about 2/3 of the climate impact of aviation, they are not yet taken into account in existing and currently planned emissions trading systems (e.g. EU ETS) or market-based measures (MBM, e.g. CORSIA 1). This research project focuses on the development of concepts for the integration of non-CO2 effects of air traffic into the EU ETS and under CORSIA. For this purpose, suitable climate metrics for assessing the relationship between non-CO2 and CO2 climate impacts are analyzed first (Part A). For selected non-CO2 calculation methodologies, the availability of the necessary data is examined and estimation procedures for non-existent data are investigated (Part B). Afterwards, the current practice in voluntary carbon markets for estimating CO2 and non-CO2 effects of aviation is presented (Part C). The additional administrative burden to verify reporting on aviation’s non-CO2 is examined in Part D. In the final step, key design parameters for the integration of non-CO2 consequences of aviation in the EU ETS and CORSIA are evaluated (Part E). The inclusion of non-CO2 effects in the EU ETS and CORSIA is highly recommended for climatelogical reasons and technically feasible, but involves an additional administrative burden for authorities and aircraft operators. The level of the resulting mitigation incentive as well as the additional effort is strongly depending on the calculation methodology of the CO2 equivalents. For this choice, a trade-off must be made between a simple operational feasibility and a high incentive level to modify flight routing and to reduce the NOx emission indices. False mitigation incentives, which can arise from to the non-linearity between non-CO2 climate effects and fuel consumption, must be prevented.