Suitable climate metrics for assessing the relation of non-CO2 and CO2 climate effects

Kurzfassung

The final report of work package 1 is separated in five sections: Introduction, Climate impact, Climate metrics, Calculation methods and Alternatives. After the introduction (Section 1) aviation emissions and the impact on climate are presented. The different atmospheric processes and lifetimes of the dif-ferent emissions are shown in Section 2, as well as the different climate sensitivities and the depend-ency from emission location. At the end of this section the level of scientific understanding of the dif-ferent climate agents are presented. The third section is focussing on climate metrics. We provide a definition of climate metrics and show why they are necessary and which requirements should be met by a suitable climate metric. Afterwards, most common climate metrics (emissions, RF, GWP, GTP and ATR) are presented and advantages as well as disadvantages are discussed individually. In addition, it is shown that also the choice of time horizon and emission development play a crucial role for assessing the relation of non-CO2 and CO2 climate effects. According to the previous we recommend the ATR with a time horizon of 100 years as a suitable climate metric for emission trading or CORSIA. The fourth section is dealing with the calculation of CO2 equivalents. Three different calculation methods are presented in detail which are further investigated in the subsequent work packages: First, a simple but potentially misguiding distance dependent factor is introduced. Afterwards a (2) latitude-height-dependent factor and a (3) complex but accurate weather and spatial dependent factor are presented. By taken more atmospheric processes into account, more benefits for for climate mitigation can be created. But however, also the amount of necessary data and the effort to calculate the equivalent CO2 emissions increases. In the last section, two alternative concepts are presented which try to create a financial incentive (price based approach) or a need (regulative approach) for operator of aircraft to reduce non-CO2 effects by charging or closing highly climate-sensitive airspaces.