Journal
ATMOSPHERIC ENVIRONMENT
Volume 244, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.atmosenv.2020.117834
Keywords
Aviation; Contrail cirrus; Climate; Radiative forcing; CO2; NOx
Funding
- UK Department for Transport
- European Union's Horizon 2020 Research and Innovation Programme by the UK National Environment Research Council (NERC) SMURPHS project [820829, NE/N006038/1]
- EU H2020 [821205]
- Norwegian Research Council (RCN) [300718]
- National Science Foundation [NSF 1540954]
- Oxford Martin Programme on Climate Pollutants
- NERC [NE/N006038/1] Funding Source: UKRI
Ask authors/readers for more resources
Global aviation operations contribute to anthropogenic climate change by emitting carbon dioxide, nitrogen oxides, water vapor, soot and sulfate aerosols, and increasing cloudiness due to contrail formation. The growth of aviation activity and climate change impact has shown a marked increase in recent years, with contrail cirrus being the largest contributor to the warming effect.
Global aviation operations contribute to anthropogenic climate change via a complex set of processes that lead to a net surface warming. Of importance are aviation emissions of carbon dioxide (CO2), nitrogen oxides (NOx), water vapor, soot and sulfate aerosols, and increased cloudiness due to contrail formation. Aviation grew strongly over the past decades (1960-2018) in terms of activity, with revenue passenger kilometers increasing from 109 to 8269 billion km yr(-1), and in terms of climate change impacts, with CO2 emissions increasing by a factor of 6.8 to 1034 Tg CO2 yr(-1). Over the period 2013-2018, the growth rates in both terms show a marked increase. Here, we present a new comprehensive and quantitative approach for evaluating aviation climate forcing terms. Both radiative forcing (RF) and effective radiative forcing (ERF) terms and their sums are calculated for the years 2000-2018. Contrail cirrus, consisting of linear contrails and the cirrus cloudiness arising from them, yields the largest positive net (warming) ERF term followed by CO2 and NOx emissions. The for-mation and emission of sulfate aerosol yields a negative (cooling) term. The mean contrail cirrus ERF/RF ratio of 0.42 indicates that contrail cirrus is less effective in surface warming than other terms. For 2018 the net aviation ERF is +100.9 milliwatts (mW) m(-2) (5-95% likelihood range of (55, 145)) with major contributions from contrail cirrus (57.4 mW m(-2)), CO2 (34.3 mW m(-2)), and NOx (17.5 mW m(-2)). Non-CO2 terms sum to yield a net positive (warming) ERF that accounts for more than half (66%) of the aviation net ERF in 2018. Using normalization to aviation fuel use, the contribution of global aviation in 2011 was calculated to be 3.5 (4.0, 3.4) % of the net anthropogenic ERF of 2290 (1130, 3330) mW m(-2). Uncertainty distributions (5%, 95%) show that non-CO2 forcing terms contribute about 8 times more than CO2 to the uncertainty in the aviation net ERF in 2018. The best estimates of the ERFs from aviation aerosol-cloud interactions for soot and sulfate remain undetermined. CO2-warming-equivalent emissions based on global warming potentials (GWP* method) indicate that aviation emissions are currently warming the climate at approximately three times the rate of that associated with aviation CO2 emissions alone. CO2 and NOx aviation emissions and cloud effects remain a continued focus of anthropogenic climate change research and policy discussions.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available