Poster's note: relevant to cirrus cloud Thinning https://www.atmos-chem-phys.net/19/8163/2019/
ACP <https://www.atmospheric-chemistry-and-physics.net/> | Articles <https://www.atmos-chem-phys.net/> | Volume 19, issue 12 <https://www.atmos-chem-phys.net/19/issue12.html> Atmos. Chem. Phys., 19, 8163-8174, 2019 https://doi.org/10.5194/acp-19-8163-2019 © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License. <https://creativecommons.org/licenses/by/4.0/> *Research article* | 27 Jun 2019 Contrail cirrus radiative forcing for future air traffic *Lisa Bock and Ulrike Burkhardt *Received: 14 Dec 2018 – Discussion started: 25 Jan 2019 – Revised: 17 May 2019 – Accepted: 23 May 2019 – Published: 27 Jun 2019 Abstract top <https://www.atmos-chem-phys.net/19/8163/2019/#top> The climate impact of air traffic is to a large degree 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 cirrus 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 climate 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 altitudes. 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 traffic areas over eastern Asia. The projected upward shift in air traffic attenuates contrail cirrus radiative forcing increases in the midlatitudes but reinforces it in the tropical areas. Climate change has an insignificant impact on global contrail cirrus radiative forcing, while regional changes are significant. Of the emission reductions it is the soot number emission reductions by 50 % that lead to a significant decrease in contrail cirrus optical depth and coverage, leading to a decrease in radiative forcing by approximately 15 %. The strong increase in contrail cirrus radiative forcing due to the projected increase in air traffic volume cannot be compensated for by the decrease in initial ice crystal numbers due to reduced soot emissions and improvements in propulsion efficiency. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/geoengineering. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/CAJ3C-04YhPJk2ENOZgSViP5v1CdftEXmqACed0FCwCB5LotL_Q%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
