Part of this is that besides CO2, the other pollution has local effects too. So places where ships moor for long periods have a local incentive to force them t

Part of this is that besides CO2, the other pollution has local effects too. So places where ships moor for long periods have a local incentive to force them to burn cleaner fuels (or plug into shore for electricity) when in their immediate area. The industry does have various plans for the wider CO2 issue, similar to the airline industry. A recurring theme is that even mild regulation or carbon pricing (or Russia invading your neighbour) provides enough motivation for a lot of low hanging fruit to be found and fixed. In shipping, the practice of going really fast then waiting around for weeks is being phased out. It mostly hinges on contracts sharing the risks when it goes wrong one time in a hundred. They've also identified that one size fits all ship designs can have efficiency impacts depending on what speed they intend to move at, which can depend on cargo and purpose. The further you reduce the CO2 the harder it gets to wring out further improvements but they have a wide range of decarbonisation plans in motion.