## 3 Results
### Global Emissions and Climate Impact Results  
The overall results in terms of emissions and climate impact of the different concepts evaluated at global fleet level are shown in Figures 15 and 16. Furthermore, the global distribution of emissions is visualized in Appendix A. The grey cells in Figures 15 and 16 indicate the changes per step. The reference aircraft D261 is used to normalize the global emissions and the Average Temperature Response (ATR). The ATR is calculated for a time frame of 100 years and 32 years of operation, starting in 2040. For the D261, the impact of CiC is responsible for 53% and the total NO\({}_{\text{x}}\) impact, consisting of increased global ozone (O\({}_{3}\)) and increased depletion rates of methane (CH\({}_{4}\)) for 23%, the carbon dioxide for 19%, and water vapour for 5%. The D261+ with conventional technology advancements for 2040 shows benefits in CO\({}_{2}\) and water vapour which correlates with the improved fuel consumption. However, the increased temperatures in the conventional combustion chamber cause higher NOx emissions, which compensates the benefit of reduced fuel consumption. Additionally, the contrail impact could potentially increase due to the correlation with the overall propulsion efficiency of the turbofan engines. Nevertheless, this has to be interpreted with care as this correlation is based just on few reference points (see Section 2.6). Despite the strongly reduced fuel consumption, the potential climate impact reduction is not significant and could even be worse, indicated by the uncertainties. For the advanced combustion chamber, the climate impact is reduced by 65%. In addition to the benefits in CO\({}_{2}\) and H\({}_{2}\)O, the advanced combustion chamber (low NOx and low soot) reduces the climate impact of CiC and NOx due the reduced NOx and particles emission of 91% and 90%, respectively. The next two concepts, D261+DropIn and D261+SAF in Figures 15 and 16, have the same technology level as the D261+ but are powered with drop-in capable kerosene, considering today's standards, and with 100% synthetic kerosene produced by PtL. Whereas the redesign has little effect at vehicle performance level, the change in climate impact is much higher. The CO\({}_{2}\) emissions and impact is strongly reduced for the D261+DropIn and vanishes for the D261+SAF. This is due to the assumption of carbon neutral fuel production incorporating Direct Air Capturing (DAC) as carbon source. For the conventional combustion chamber, the contrail impact is lowered due to the reduced soot emissions of the drop-in and PtL fuel, see Table 1. The gradual reduction for the D261+DropIn and D261+SAF with advanced combustion chambers results not from the reduced contrail effect, as the soot emissions are already at the lowest provable level where the particles in the environment are dominating the properties of contrails, but from the CO\({}_{2}\) neutral production with DAC. All concepts described thus far are operated at performance optimized flight levels. The next concept, displayed in Figures 15 and 16, reduces the maximum flight level as well as the cruise Mach number to 290 and 0.75, respectively. This results in 5% higher direct operating costs (DOC) compared to the D261+SAF at optimum flight levels, mainly caused by higher crew costs, capital expenditures, and fuel consumption. As the CO\({}_{2}\) impact is eliminated within this scenario, the reduced aircraft performance is merely visible. However, the altitude reduction strongly affects the non-CO\({}_{2}\) effects, which leads to a reduction of 56% compared to the non restricted case and 69% compared to the  
Figure 14: Block-Energy difference for PtL concept D261+SAF (**a**) and LH2 concept D261+H2 (**b**). reference scenario with conventional combustion. For the advanced combustion chamber, the reduction compared to the reference reaches 93%. The uncertainties of all low NOx and low soot combustion are rather high, as the effect of reduced soot emissions at contrail impact is not yet understood profoundly.