Integration of air quality and climate change policies in shipping: The case of sulphur emissions regulation

Ship air pollution has attracted much attention from the shipping community. Besides Greenhouse Gases (such as carbon dioxide) that contribute to Climate Change, shipping emits many other gases including sulphur and nitrous oxides. There is much scientific evidence that measures to reduce these pollutants do improve air quality but, at the same time, contribute to the acceleration of global warming, because they result in removing the cooling effect of these gases. Until now climate change and air quality regulations have been discussed independently. This work tries to assess the effect of policies to improve air quality on climate change, and vice versa. This paper discusses an approach to assess the impact of SOx reduction measures on global warming by presenting a way to place both emissions on a common scale to allow a comparison between them and to estimate their aggregate effect. Such integration can lead to better decisions by policymakers.