Climate impact of supersonic air traffic: an approach to optimize a potential future supersonic fleet – results from the EU-project SCENIC

Abstract

Abstract. The demand for intercontinental transportation is increasing and people are requesting short travel times, which supersonic air transportation would enable. However, besides noise and sonic boom issues, which we are not referring to in this investigation, emissions from supersonic aircraft are known to alter the atmospheric composition, in particular the ozone layer, and hence affect climate significantly more than subsonic aircraft. Here, we suggest a metric to quantitatively assess different options for supersonic transport with regard to the potential destruction of the ozone layer and climate impacts. Options for fleet size, engine technology (nitrogen oxide emission level), cruising speed, range, and cruising altitude, are analyzed, based on SCENIC emissions scenarios for 2050, which underlay the requirements to be as realistic as possible in terms of e.g. economic markets and profitable market penetration. This methodology is based on a number of atmosphere-chemistry and climate models to reduce model dependencies. The model results differ significantly in terms of the response to a replacement of subsonic aircraft by supersonic aircraft. However, model differences are smaller when comparing the different options for a supersonic fleet. The base scenario, where supersonic aircraft get in service in 2015, a first fleet fully operational in 2025 and a second in 2050, lead in our simulations to a near surface temperature increase in 2050 of around 7 mK and with constant emissions afterwards to around 21 mK in 2100. The related total radiative forcing amounts to 22 mWm²in 2050, with an uncertainty between 9 and 29 mWm². A reduced supersonic cruise altitude or speed (from March 2 to Mach 1.6) reduces both, climate impact and ozone destruction, by around 40%. An increase in the range of the supersonic aircraft leads to more emissions at lower latitudes since more routes to SE Asia are taken into account, which increases ozone depletion, but reduces climate impact compared to the base case.

AirClim: an efficient tool for climate evaluation of aircraft technology

“…Efficacies for a variety of climate agents are taken from Ponater et al (2005Ponater et al ( , 2006. The climate sensitivities used in this study are identical to those in Grewe et al (2007) (their Table 7). …”

“…2.4.1) depending on the regarded 3-D emissions. For the lifetime of a stratospheric perturbation an uncertainty range of ±40% is regarded following Grewe et al (2007), whereas for the troposphere only ±20% are taken into account, since model uncertainties in e.g. simulating tropospheric ozone lifetimes agree within this range (Stevenson et al, 2006).…”

Do supersonic aircraft avoid contrails?

“…The different SCENIC air traffic datasets are discussed in detail in Rogers et al (2007) 1 . Here we give a short summary of the main characteristics of the subsonic (S1 and S4) and mixed fleet scenarios (S2 and S5) for the years 2025 and 2050 (Table 1).…”

Radiative forcing caused by rocket engine emissions

“…Ross et al [2010] demonstrated the significant potential rockets have to alter regional RF as well as the global circulation, should certain types of space transportation grow as planned. In this context, it is perplexing that detailed models of supersonic transport emissions continue to appear in the literature [e.g., Grewe et al, 2007] when such vehicles are not likely to appear soon whereas space transportation is a growing actuality.…”