Climate impact of air traffic
CO2 emissions are not the only contributor to man-made climate change. Concerning air traffic, they account for around one third of its climate impact, latest scientific evidence suggests. The remaining two thirds are contributed by so-called "non-CO2 effects". These are caused by the emission of nitrogen oxides, water vapor, soot, and aerosols, as well as by the effect of contrails and contrail cirrus clouds.
There is a great need for research in this area, as their sources, transport and effects have not yet been fully investigated. If all these effects are included, aviation is responsible for 3.5 percent of global warming to date.