Uncertainties in climate assessment for the case of aviation NO

摘要

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 decompo sition captures major features of the ensemble, and also shows which processes drive the total uncertainty in several climate me trics. 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 an ticorrelation between the short-lived and long-lived RF perturba tions (R～2 = 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.