This report presents research on international shipping emissions and climate change undertaken at The University of Manchester by the Tyndall Centre for Climate Change Research and the Sustainable Consumption Institute (SCI). The research considers the role that the shipping sector could play in mitigating total global emissions, with a particular focus on assessing the potential for UK unilateral action. The report begins by quantifying the scale of the climate change challenge faced, considers the role of shipping in relation to mitigation, presents and assesses a range of apportionment methods for estimating CO2 emissions from international shipping at a national scale, and quantifies the UK