TagAtmospheric Chemistry and Physics(1)

© Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. Contrail cirrus radiative forcing for future air traffic Lisa Bock and Ulrike Burkhardt Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany Correspondence: Lisa Bock (lisa.bock@dlr.de) Received: 14 December 2018 – Discussion started: 25 January 2019 Revised: 17 May 2019 – Accepted: 23 May 2019 – Published: 27 June 2019 Abstract. The climate impact of air traffic is to a large de- gree caused by changes in cirrus cloudiness resulting from the formation of contrails. Contrail cirrus radiative forcing is expected to increase significantly over time due to the large projected increases in air traffic. We use ECHAM5-CCMod, an atmospheric climate model with an online contrail cir- rus parameterization including a microphysical two-moment scheme, to investigate the climate impact of contrail cirrus for the year 2050. We take into account the predicted increase in air traffic volume, changes in propulsion efficiency and emissions, in particular soot emissions, and the modification of the contrail cirrus climate impact due to anthropogenic cli- mate change. Global contrail cirrus radiative forcing increases by a factor of 3 from 2006 to 2050, reaching 160 or even 180 mW m−2, which is the result of the increase in air traffic volume and a slight shift in air traffic towards higher alti- tudes. Large increases in contrail cirrus radiative forcing are expected over all of the main air traffic areas, but relative increases are largest over main air…