Comparison of model estimates of the effects of aviation emissions on atmospheric ozone and methane

One of the significant uncertainties in understanding the effects of aviation on climate is the effects of aviation emissions on ozone and atmospheric chemistry. In this study the effects of aviation emissions on atmospheric ozone for 2006 and two projections for 2050 are compared among seven models. The models range in complexity from a two-dimensional coupled model to three-dimensional offline and fully coupled three-dimensional chemistry-climate models. This study is the first step in a critical assessment and comparison among these model results. Changes in tropospheric O-3 burdens range from 2.3 Tg-O-3/Tg-N to 3.0 Tg-O-3/Tg-N, ozone radiative forcings range from 6 to 37 mW/m(2), and methane radiative forcings range from -8.3 to -12.5 mW/m(2) for the 2006 aviation emissions. As a group, the chemistry transport models tend to have similar responses while the fully coupled models tend to separate from this group and do not show similar responses to each other.