Global climate impact of civil aviation for standard and desulfurized jet fuel

Aircraft emissions can affect climate change through increasing carbon dioxide (CO 2 ) but also via a host of other short‐lived non‐CO 2 effects that are complex, involve impacts that are both warming and cooling and are unique to this sector. Previous assessments of aviation climate impacts have used a segmented approach whereby each effect was calculated separately and the effects summed. Integrated approaches using newly available Earth System models that allow simulation of more realistic interactions between effects are now possible. The NASA GISS Earth System Model (ModelE) is applied to reassess the net climate impact of civil aviation emissions based on a new inventory for year 2006 developed using the Federal Aviation Administration's (FAA) Aviation Environmental Design Tool (AEDT). The model simulates all known non‐CO 2 aviation climate impacts except linear contrails and contrail‐cirrus for which a recent estimate is assumed. For standard jet fuel, the net global climate impact for sustained constant year 2006 aviation emissions is +44 ± 10 mWm −2 (2/3 due to non‐CO 2 effects) on a 20‐year timescale and +73 ± 10 mWm −2 (over 1/3 due to non‐CO 2 effects) on a 100‐year timescale. For desulfurized jet fuel, the net climate impact is +40 ± 10 mWm −2 on the 20‐year timescale, slightly less warming than the standard fuel case due to the complex interplay between sulfate and nitrate and the competition for ammonia. Ozone (O 3 ) greenhouse efficiency (W per g O 3 change) is 20–60% larger for aviation than surface transportation emissions.