Shipping and the
environment
Shipping accounts for less than three per cent of CO2 emissions. However, in tonne-mile terms it delivers the vast majority of the world's transported goods by a very energy-efficient mode of transport. Today, the diesel engines which power most commercial vessels produce emissions of SOx and NOx. SOx emissions are caused by the widespread use of high-sulphur fuel in marine engines.
When ships operate in coastal waters, NOx and SOx emissions contribute to reduced air quality and acid rain. SOx emissions are also associated with the formation of low-level cloud, which is thought to have a cooling effect. This tends to offset global warming but also has other climate impacts.
This combination of environmental drivers, coupled with the increasing size of the global fleet, raises important questions about future vessel design and, in particular, the choice of propulsion system and fuel type.
