Possible influence of anthropogenic aerosols on cirrus clouds and anthropogenic forcing

Penner, Joyce E.; Chen, Yang; Wang, Minghuai; Liu, Xiaohong

doi:10.5194/acp-9-879-2009

Cited by 117 publications

(151 citation statements)

References 75 publications

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“…Other important RFs from aviation include CO 2 , contrails, and induced cirrus. Current CO 2 forcing is about þ28 mW m þ120 mW m −2 (36,37)]. These steady-state contrail and cirrus RF estimates should be increased by about 15% to compare with the 1 TgðNÞ a −1 values used here.…”

Section: Discussionmentioning

confidence: 99%

Uncertainties in climate assessment for the case of aviation NO

Holmes

Tang²,

Prather³

2011

Proc. Natl. Acad. Sci. U.S.A.

122

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Nitrogen oxides emitted from aircraft engines alter the chemistry of the atmosphere, perturbing the greenhouse gases methane (CH 4 ) and ozone (O 3 ). We quantify uncertainties in radiative forcing (RF) due to short-lived increases in O 3 , long-lived decreases in CH 4 and O 3 , and their net effect, using the ensemble of published models and a factor decomposition of each forcing. The decomposition captures major features of the ensemble, and also shows which processes drive the total uncertainty in several climate metrics. Aviation-specific factors drive most of the uncertainty for the short-lived O 3 and long-lived CH 4 RFs, but a nonaviation factor dominates for long-lived O 3 . The model ensemble shows strong anticorrelation between the short-lived and long-lived RF perturbations (R 2 ¼ 0.87). Uncertainty in the net RF is highly sensitive to this correlation. We reproduce the correlation and ensemble spread in one model, showing that processes controlling the background tropospheric abundance of nitrogen oxides are likely responsible for the modeling uncertainty in climate impacts from aviation.aviation emissions | error correlation | model sensitivity Q uantifying uncertainties in climate processes is a major priority for climate research, as exemplified by the widespread use of probability distributions and uncertainties in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (1). To understand and attribute changes in the greenhouse gases and aerosols that force climate change, we rely on chemistry-transport models (CTMs), which require further characterization of their errors (e.g., 2-5). Aviation emissions are estimated to contribute 5% of anthropogenic climate forcing, with a nearly threefold uncertainty (6). This forcing occurs mainly through aviation-induced cloudiness and emissions of CO 2 and nitrogen oxides. Climate impacts of other aviation emissions-CO, SO 2 , soot, hydrocarbons, and water vapor-are highly uncertain, but estimated to be much smaller (6). In this paper we quantify one type of climate forcing and its uncertainty, the impact of aviation emissions on the greenhouse gases ozone (O 3 ) and methane (CH 4 ).Aircraft engines emit NO and NO 2 (NOx), which are indirect greenhouse gases through their chemical reactions impacting O 3 production and the CH 4 lifetime. As an O 3 precursor, NOx emissions increase the tropospheric column of O 3 and its radiative forcing. Aviation NOx emissions have a stronger impact on O 3 than surface emissions on a per molecule basis because they occur at high altitudes (7). Previous model-based estimates of the amount of O 3 generated by aviation NOx emissions vary by up to 100% and these differences have been attributed to a range of causes: e.g., the ratios of NO∶NO 2 and OH∶HO 2 , background NOx levels (8), location and time of emissions (9-11), the amount of sunlight (12), and atmospheric mixing (13,14).Early work on climate forcing by aviation assumed that the impacts would be short-lived and limited to the northern latitudes ...

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Section: Discussionmentioning

confidence: 99%

Uncertainties in climate assessment for the case of aviation NO

Holmes

Tang²,

Prather³

2011

Proc. Natl. Acad. Sci. U.S.A.

122

View full text Add to dashboard Cite

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“…By assuming high heterogeneous ice nucleation efficiency for aviation BC, Penner et al (2009) and Liu et al (2009) found that aviation BC could produce radiative forcing of a wide range, either positive or negative, under different sensitivity tests. More recently, Zhou and Penner (2014) simulated large aviation BCinduced radiative forcing when preactivation of aviation soot was assumed.…”

Section: Aviation Bcmentioning

confidence: 99%

“…Hendricks et al (2005Hendricks et al ( , 2011 found that aviation BC could significantly increase the crystal concentration if aviation BC could serve efficiently as ice nuclei. Furthermore, Penner et al (2009) reported, by assuming aviation BC as highly efficient heterogeneous ice nuclei, that aviation BC could induce an indirect forcing ranging between −161 and +25 mW m −2 under different sensitivity tests. Liu et al (2009) also found a similar range for the forcing of aviation BC with high uncertainty depending on the assumptions made.…”

Section: Introductionmentioning

confidence: 99%

Simulated 2050 aviation radiative forcing from contrails and aerosols

Chen

Gettelman

2016

Atmos. Chem. Phys.

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Abstract. The radiative forcing from aviation-induced cloudiness is investigated by using the Community Atmosphere Model Version 5 (CAM5) in the present (2006) and the future (through 2050). Global flight distance is projected to increase by a factor of 4 between 2006 and 2050. However, simulated contrail cirrus radiative forcing in 2050 can reach 87 mW m −2 , an increase by a factor of 7 from 2006, and thus does not scale linearly with fuel emission mass. This is due to non-uniform regional increase in air traffic and different sensitivities for contrail radiative forcing in different regions.CAM5 simulations indicate that negative radiative forcing induced by the indirect effect of aviation sulfate aerosols on liquid clouds in 2050 can be as large as −160 mW m −2 , an increase by a factor of 4 from 2006. As a result, the net 2050 radiative forcing of contrail cirrus and aviation aerosols may have a cooling effect on the planet. Aviation sulfate aerosols emitted at cruise altitude can be transported down to the lower troposphere, increasing the aerosol concentration, thus increasing the cloud drop number concentration and persistence of low-level clouds. Aviation black carbon aerosols produce a negligible net forcing globally in 2006 and 2050 in this model study.Uncertainties in the methodology and the modeling are significant and discussed in detail. Nevertheless, the projected percentage increase in contrail radiative forcing is important for future aviation impacts. In addition, the role of aviation aerosols in the cloud nucleation processes can greatly influence on the simulated radiative forcing from aircraft-induced cloudiness and even change its sign. Future research to confirm these results is necessary.

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“…The effect of AIC has been estimated from observational data and the level of scientific understanding is judged to be very low. Modeling studies of the climate impact of aviation soot cirrus remain inconclusive because of the uncertainties in soot abundance and ice-nucleating properties (Hendricks et al 2005;Penner et al 2008;Liu et al 2009). Therefore, we will not discuss this issue any further in this paper, even though the effect potentially may be important.…”

mentioning

confidence: 99%