This scheme is closed to other trading systems, such as the EU ETS and the CDM. We conclude that an emissions trading scheme is the most effective and the most cost-effective global MBM. It also scores well on most of the other criteria. The GHG fund is slightly less effective and less cost-effective, because it does not incentivise the shipping sector to implement all cost-effective abatement options. The Baseline-and-Credit Scheme is less effective because it does not have an emissions cap, and less cost-effective because it does not incentivise all cost-effective abatement options and is closed to trade with other sectors and the CDM.