The Carbon Intensity Indicator (CII) is one of the short-term measures introduced by the International Maritime Organization(IMO) to reduce greenhouse gas emissions from shipping. This policy brief reviews the measure and providesimprovement recommendations, focusing on how emission standards at sea and at port should be dealt with. Key Highlights: CII is currently insufficient for capturing emissions accurately at sea and at port and incentivising emission reduction A range of revision options could be considered such as excluding port emissions, adjustments for time at port, or separate metrics for at sea and at port Other areas that could be considered include allowance for actual cargo, well-to-wake emissions, and pilot fuel Recommended revision for CII is to use separate metrics for at sea and at port emissions.