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Climate impact of anthropogenic activities is more and more of public concern. But while CO2 emissions are accounted in emissions trading and mitigation plans, emissions of non-CO2 components contributing to climate change receive much less attention. One of the anthropogenic emission sectors, where non-CO2 effects play an important part, is aviation. Hence, for a quantitative estimate of total aviation climate impact, assessments need to comprise both CO2 and non-CO2 effects (e.g., water vapor, nitrogen dioxide, and contrails), instead of calculating and providing only CO2 impacts. However, while a calculation of CO2 effects relies directly on fuel consumption, for non-CO2 effects detailed information on aircraft trajectory, engine emissions, and ambient atmospheric conditions are required. As often such comprehensive information is not available for all aircraft movements, a simplified calculation method is required to calculate non-CO2 impacts. In our study, we introduce a simple calculation method which allows quantifying climate assessment relying on mission parameters, involving distance and geographic flight region. We present a systematic analysis of simulated climate impact from more than 1000 city pairs with an Airbus A330-200 aircraft depending on the flight distance and flight region to derive simplified but still realistic representation of the non-CO2 climate effects. These new formulas much better represent the climate impact of non-CO2 effects compared to a constant CO2 multiplier. The mean square error decrease from 1.18 for a constant factor down to 0.24 for distance dependent factors and can be reduced even further to 0.19 for a distance and latitude dependent factor. [ABSTRACT FROM AUTHOR]

Decadal means of ozone fields from transient E39/C climate-chemistry simulations (1960-2019) are analysed and temporally developing ozone radiative forcings (RF) are investigated which result from individual ozone precursor sources like road traffic, industry, air traffic, etc. We study how effective NOx emissions from different sources produce ozone. This ozone production efficiency is mainly dependent on the altitude of NOx emission and on the amount of background NOx. For example, our study shows that the ozone production efficiency of lightning and air traffic have a five and two time higher ozone production efficiency than ground based sources. The radiative efficiency of ozone (i.e. the radiative forcing per molecule) is mainly dependent on the surface temperature, but also, to a lesser degree, on the altitude of added ozone. Lightning, for example, causes the highest specific RF due to the fact that lightning primarily enhances ozone in low latitudes in the mid-troposphere. Superimposed on these effects, is a saturation effect which causes a decreasing RF efficiency with increasing background ozone. A consequence of this saturation effect is an underestimation of total RF by about 10% if the component RFs of individual ozone sources are calculated separately and added up afterwards. The results show that the time development of emissions (1960-2019) control the RF changes for most sources. RF changes are slightly reduced due to a changing atmospheric composition (10-25%) for all but the aircraft sources, and due to RF saturation (2-5%). [ABSTRACT FROM AUTHOR]