Impact of increasing ship emissions on air quality and deposition over Europe by 2030

A global chemistry-transport model has been used to study the effect of shipping emissions on air quality and ecosystems over Europe, through changes in surface ozone and surface sulphate aerosols, and changes in the deposition of sulphur and oxidised nitrogen. Scenarios are chosen to determine the impact of current (2000) shipping emissions, and the combined impact of changes in land-based and shipping emissions by 2030. The effects of shipping on ozone are small, compared to land-based emissions changes, and can be both positive and negative. Due to the non-linear nature of ozone chemistry, the effects of shipping depend on the magnitude of the emission change, and on the choice of scenario for the land-based emissions. The effects on sulphate aerosol levels and deposition fluxes of sulphate aerosols and oxidised nitrogen species are larger, and are comparable to expected changes in land-based emissions. This is particularly true for SO2 emissions from shipping. SO2 has a sufficiently short lifetime that most of the impacts are felt within the European region, although much of that is over the sea. The increase in sulphate aerosols and sulphur deposition due to the SO2 from shipping will offset 75 % of the benefits in air quality that would be expect from land-based emission controls under the SRES A2 scenario.