30 Mar 2022
30 Mar 2022
Status: a revised version of this preprint is currently under review for the journal ACP.

Aviation contrail climate effects in the North Atlantic from 2016–2021

Roger Teoh1, Ulrich Schumann2, Edward Gryspeerdt3, Marc Shapiro4, Jarlath Molloy5, George Koudis5, Christiane Voigt2,6, and Marc Stettler1 Roger Teoh et al.
  • 1Centre for Transport Studies, Department of Civil and Environmental Engineering, Imperial College London, London, SW7 2AZ, United Kingdom
  • 2Institute of Atmospheric Physics, Deutsches Zentrum für Luft- und Raumfahrt, 82234 Oberpfaffenhofen, Germany
  • 3Grantham Institute – Climate Change and Environment, Imperial College London, London, SW7 2AZ, United Kingdom
  • 4Orca Sciences, 4110 Carillon Point, Kirkland, WA 98033, United States
  • 5NATS, 4000 Parkway, Whiteley, Fareham, Hampshire, PO15 7FL, United Kingdom
  • 6Institute of Atmospheric Physics, University Mainz, 55099 Mainz, Germany

Abstract. Around 5 % of anthropogenic radiative forcing (RF) is attributed to aviation CO2 and non-CO2 impacts. This paper quantifies aviation emissions and contrail climate forcing in the North Atlantic, one of the world’s busiest air traffic corridors, over 5 years. Between 2016 and 2019, growth in CO2 (+3.13 % per annum, p.a.) and nitrogen oxide emissions (+4.5 % p.a.) outpaced increases in flight distance (+3.05 % p.a.). Over the same period, the annual mean contrail cirrus net RF (204–280 mW m-2) showed significant interannual variability caused by variations in meteorology. Responses to COVID-19 caused significant reductions in flight distance travelled (-66 %), CO2 emissions (-71 %), and the contrail net RF (-66 %) compared to the prior one-year period. Around 12 % of all flights in this region cause 80 % of the annual contrail energy forcing, and the factors associated with strongly warming/cooling contrails include seasonal changes in meteorology and radiation, time of day, background cloud fields, and engine-specific non-volatile particulate matter (nvPM) emissions. Strongly warming contrails in this region are generally formed in wintertime, close to the tropopause, between 15:00 and 04:00 UTC, and above low-level clouds. The most strongly cooling contrails occur in the spring, in the upper troposphere, between 06:00 and 15:00 UTC, and without lower-level clouds. Uncertainty in the contrail cirrus net RF (216–238 mW m-2) arising from meteorology in 2019, is smaller than the interannual variability. The contrail RF estimates are most sensitive to the humidity fields, followed by nvPM emissions and aircraft mass assumptions. This longitudinal evaluation of aviation contrail impacts contributes a quantified understanding of inter-annual variability and informs strategies for contrail mitigation.

Roger Teoh et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-169', Xavier Vancassel, 21 Apr 2022
  • RC2: 'Comment on acp-2022-169', Anonymous Referee #2, 22 Apr 2022
  • AC1: 'Comment on acp-2022-169', Marc Stettler, 26 May 2022

Roger Teoh et al.


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Short summary
Aircraft condensation trails (contrails) contribute to over half of the climate forcing attributable to aviation. This study uses historical air traffic and weather data to simulate contrails in the North Atlantic over 5 years, from 2016 to 2021. We found large intra- and inter-year variability in contrail radiative forcing and observed a 66 % reduction due to COVID-19. The most warming contrails predominantly result from night-time flights in winter.