Aviation Climate Impact: Scientific Status

Kurzfassung

Aviation in 2005 was recently estimated to cause about 5% of total anthropogenic radiative forcing (range 2–14%). About 2/3 of this RF comes from non-CO2 emis-sions, with the largest share from aviation induced cloudiness. NOx from subsonic aviation produce ozone which is a greenhouse gases, but also reduces methane, another greenhouse gas, and the methane reduction in turn causes a long-time ozone reduction. Consequently, one cannot exclude that aviation NOx may ultimately cool the Earth system. Satellite observations of cirrus cover in correlation with traffic and modelling. suggest that contrails are forming the largest contribution to the non-CO2 aviation climate im-pacts. The climate impact of contrails increases with the number of soot particles emitted. Model studies show that small changes in flight altitude, depending on the actual weather situation can reduce the global radiative forcing from contrail cirrus by more than a factor of two.