Emission metrics for quantifying regional climate impacts of aviation
Marianne T. Lund1, Borgar Aamaas1, Terje Berntsen1,2, Lisa Bock3, Ulrike Burkhardt3, Jan S. Fuglestvedt1, and Keith P. Shine41CICERO, Center for International Climate and Environmental Research Oslo, Norway 2Department of Geosciences, University of Oslo, Norway 3Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany 4Department of Meteorology, University of Reading, UK
Received: 31 Jan 2017 – Accepted for review: 06 Feb 2017 – Discussion started: 07 Feb 2017
Abstract. This study examines the impacts of emissions from aviation in six source regions on global and regional temperature. We consider the NOx-induced impacts on ozone and methane, aerosols and contrail-cirrus formation, and calculate the global and regional climate metrics Global Warming Potential (GWP), Global Temperature change Potential (GTP) and Absolute Regional Temperature change Potential (ARTP). GWPs and GTPs vary by a factor 2–4 between source regions. We find the highest aviation aerosol metric values for South Asian emissions, while contrail-cirrus metrics are higher for Europe and North America, where contrail formation is prevalent, and South America plus Africa, where the optical depth is large once contrails form. The ARTP illustrate important differences in the latitudinal patterns of radiative forcing (RF) and temperature response: The temperature response in a given latitude band can be considerably stronger than suggested by the RF in that band, also emphasizing the importance of large-scale circulation impacts. To place our metrics in context, we quantify the temperature response in the four broad latitude bands following a one-year pulse emission from present-day aviation, including CO2. Aviation over North America and Europe cause the largest net warming impact in all latitude bands, reflecting the higher air traffic activity here. For all regions, the largest single warming contribution is from contrail-cirrus 20 years after the emissions, while CO2 becomes dominant at 100 years, although contrail-cirrus remain important in several regions also on this time scale. Our emission metrics can be further used to estimate regional temperature impact under alternative aviation emission scenarios. A first evaluation of the ARTP in the context of aviation suggests that further work to account for vertical sensitivities in the relationship between RF and temperature response would be valuable for further use of the concept.
Lund, M. T., Aamaas, B., Berntsen, T., Bock, L., Burkhardt, U., Fuglestvedt, J. S., and Shine, K. P.: Emission metrics for quantifying regional climate impacts of aviation, Earth Syst. Dynam. Discuss., doi:10.5194/esd-2017-11, in review, 2017.