This paper's purpose is to investigate the role of sea ports in helping to mitigate the GHG emissions associated with the end-to-end maritime transport chain. The analysis is primarily focused on the UK, but is international in application. The paper is based on both the analysis of secondary data and information on actions taken by ports to reduce their emissions, with the latter data collected for the main UK ports via their published reports and/or via interviews. Only a small number of ports (representing 32% of UK port activity) actually measure and report their carbon emissions in the UK context. The emissions generated by ships calling at these ports are analysed using a method based on Department for Transport Maritime Statistics Data. In addition, a case example (Felixstowe) of emissions associated with HGV movements to and from ports is presented, and data on vessel emissions at berth are also considered. Our analyses indicate that emissions generated by ships during their voyages between ports are of a far greater magnitude than those generated by the port activities. Thus while reducing the ports' own emissions is worthwhile, the results suggest that ports might have more impact through focusing their efforts on reducing shipping emissions.