To minimise the impact of air traffic on climate is a multidisciplinary and cooperative task with many options. Under discussion are the use of more advanced and lighter materials, more efficient propulsion techniques, and innovative designs. In addition to technological measures at the air vehicles, improvements in air operations and routings may also contribute to a reduction of negative climate effects. Atmospheric layers which are conducive to the generation of condensation trails could by avoided by higher or lower cruising levels. Long-distance flights could be segmented to avoid the carriage of heavy on-board fuel volumes. Such operational options may of course necessitate technical adaptations to avert excess energy consumptions.
In general, it is necessary to assess all options with respect to air quality and climate impact, to provide a better base for decisions to the industry, society and politics. Of course, a certain margin of uncertainty still has to be taken into account. Therefore, it is necessary to better understand the related atmospheric processes, e.g., the formation of condensation trails or clouds, the transport of tracers, chemical transformations, and radiation. The reduction of uncertainties is an important part of the analysis of mitigation strategies.
Minimising negative climate effects is an iterative process of technological and operational measures, and repeated impact assessments. It is therefore necessary to supplement the existing complex climate-chemistry models with fast and efficient, however less accurate, models.