BECOM

Aviation contributes to approximately 3.5% of total anthropogenic climate change. Almost two thirds of the climate impact of aviation is caused by non-CO2 climate effects, which include physical processes (cloud formation) and chemical reactions (including ozone production).

One of the most obvious and significant non-CO2 effects is the formation of visible contrails, which can grow into persistent contrail cirrus clouds within ice-saturated regions. The existing meteorological environmental conditions (particularly temperature and humidity) largely determine the atmospheric lifespan of contrails. Depending on the radiation conditions (position of the sun, brightness of the surface and other clouds), contrails can have a warming or cooling effect, as they both scatter solar radiation back into space and thus cool it, and also keep radiation emitted from the earth's surface in the atmosphere. Depending on the aircraft type, flight region, altitude, time of day and current weather, the climate impact of a contrail can vary greatly. However, when averaged over the globe and day and night, contrail cirrus waves lead to a significant warming of the atmosphere.