Boundary layer ozone pollution caused by future aircraft emissions

[1] In addition to their impact on the radiative forcing of climate and on the composition of the upper-troposphere and lower-stratosphere region, global aircraft NOx emissions are found to contribute significantly to transport emission induced future ozone air pollution in Europe and in the United States. Based on various projections of 2050 emissions of short-lived pollutants by the three major transport sectors (i.e., road transportation, shipping, and aircraft), we show that aircraft NOx exhaust contribute by 30–40% to the summertime 8h-average daily maximum surface ozone increase due to transport emissions in Europe and in the United States. Depending on the future scenario, over these two regions, an annual mean contribution of aircraft emissions of 25–48% to the boundary layer ozone burden increase associated with transport emissions in 2050 is simulated. Shipping emissions also represent a significant, and often dominant, contribution to future boundary layer ozone change due to transport emissions over land downwind of maritime corridors in the range 32–60% depending on the emission scenario. In the context of tighter emission standards for road transport in the future, these results indicate that aircraft and shipping emissions deserve consideration as a mean to improve air quality and reduce ozone pollution episodes.