© Author(s) 2007. This work is licensed under a Creative Commons License. Atmospheric Chemistry and Physics Multi-model simulations of the impact of international shipping on

Abstract. The global impact of shipping on atmospheric chemistry and radiative forcing, as well as the associated uncertainties, have been quantified using an ensemble of ten state-of-the-art atmospheric chemistry models and a pre-defined set of emission data. The analysis is performed for present-day conditions (year 2000) and for two future ship emission scenarios. In one scenario ship emissions stabi-lize at 2000 levels; in the other ship emissions increase with a constant annual growth rate of 2.2 % up to 2030 (termed the “Constant Growth Scenario ” (CGS)). Most other an-thropogenic emissions follow the IPCC (Intergovernmental Panel on Climate Change) SRES (Special Report on Emis-sion Scenarios) A2 scenario, while biomass burning and nat-ural emissions remain at year 2000 levels. An intercompari