[1] 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 twodimensional 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.

Strong growth in the civil aviation sector will accelerate in the future. Here, we confront the future net chemical (ozone, methane, sulfate, nitrate, black carbon, and water vapor) global climate impact of aviation at 2050 for three novel plausible scenarios constructed at the Volpe National Transportation Center using the U.S. Federal Aviation Administration (FAA) Aviation Environmental Design Tool (AEDT). The aviation net chemical climate impact is cooling in all cases and increases from −10 ± 4 mW m−2 in the contemporary climate up to –69 ± 21 mW m−2 by 2050. Future improvements in fuel efficiency provide the opportunity to reduce aviation's net chemical climate impact by ~50% relative to a baseline scenario of unconstrained growth. On the 20 year time horizon, the cooling net aviation chemical climate impact masks the aviation CO2 global warming by up to 50–100% in the contemporary and future atmospheres.

Abstract:A global land cover classification data set is used to divide the globe into seven regions to study surface temperature changes over different vegetation/surface classes. Statistically significant warming is found from the year 1900 over all regions (except for the ice sheets over Greenland and Antarctica). Outputs from three coupled climate models (CGCM2, HadCM2 and the Parallel Climate Model (PCM)) are used to examine the detection and attribution of surface temperature trends over the various vegetation classes for the past half century. An anthropogenic warming trend is detected in six of the seven regions. Observed trends are consistent with those simulated in response to greenhouse gas and sulfate aerosol forcing except over tropical forest and water where the models appear to overestimate the warming. The similarity between the resultant scaling factors for each region from the different models underscores the reliability of our detection results.

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