Growing scientific evidence indicates that contrails, and especially aircraft-induced cirrus, have a significant overall warming effect. Chemical and physical processes can lead to contrail plumes and cirrus, depending on local atmospheric conditions (humidity and temperature), and on engine emissions.
Emission standards do not take contrail formation into account. Operational measures, such as tactical (real time) and strategic (planning) avoidance of these critical locations and timing, may prove beneficial. A relatively small change in altitude may reduce the contrails significantly. Interdependencies on fuel use, flight time diversion, and airspace capacity must be assessed.