Mid‐21st century chemical forcing of climate by the civil aviation sector

Abstract

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.

The global impact of the transport sectors on atmospheric aerosol: simulations for year 2000 emissions

“…They include yearly and monthly emissions at 0.5 • resolution for gases (CO, NO x , non-methane hydrocarbons (NMHCs), NH 4 and SO 2 ) and aerosols (black and organic carbon) for 12 sectors (biomass burning and anthropogenic sources, including land-based transport, international shipping and aviation as individual sectors). The NMHC speciation is realized according to the speciation fractions by von Kuhlmann et al (2003), which are consistent with the chemical mechanism of EMAC. The injection heights for the anthropogenic sectors (6 levels in the range 45-800 m) and for biomass burning (6 levels in the range 0-6 km) are chosen according to Pozzer et al (2009) and to the AeroCom recommendations (Dentener et al, 2006, hereafter D06), respectively.…”

“…In this region, the effect of aircraft induces also an interesting decrease in the NO 3 burden. This is caused by the formation of additional ammonium sulfate from aviation-induced SO 2 , which results in less ammonium available for the formation of ammonium nitrate, a typical effect in NH 3 -limited environments such as the upper troposphere (Unger et al, 2013).…”

The global impact of the transport sectors on atmospheric aerosol in 2030 – Part 2: Aviation

“…Another interesting aspect is the negative value for aerosol nitrate in Fig. 5, between −3 and −10 ng m −3 : this is a typical effect of the NH 3 -limited environment in the UTLS (Unger et al, 2013;R13) and is due to the competition between nitrate and sulfate for the available ammonium. We lastly note that the changes in the background concentrations as induced by the other sectors (right column of Figs.…”

“…Their estimate for the indirect effect cannot be compared with ours as they only considered the effect of BC on cirrus clouds, which is not covered here. The future impacts of aviation emissions on climate have also been simulated by Unger et al (2013), using RCP4.5 for background emissions and considering three different technology scenarios for aviation in 2050. However, their study only considered the direct aerosol effect (sulfate, nitrate and black carbon), reporting a range of [−65; −20] mW m −2 .…”

“…Unger et al (2013) discussed the future effects of aviation-induced aerosol, following RCP4.5 for the background combined with several aviation emission scenarios. They found that cooling effects induced by short-lived compounds can neutralize or even overcome the CO 2 warming, depending on the time horizon under consideration.…”