Many ships use diesel fuel, particularly when entering and leaving port. Diesel fuel produces less air pollution than heavy bunker oil which has a higher sulphur content resulting in sulphur dioxide emissions. New rules requiring ships to only use low sulphur fuel oil are effective from 21 November 2006, along with several other measures to minimise air pollution from ships.

Operational Measures for ships to reduce greenhouse gasses

• Until international agreement is reached on additional regulations to reduce greenhouse gas emissions by ships, the following voluntary measures have been suggested
  • ships reduce their speed by half a knot
  • ships use weather routing systems to avoid storms and strong head winds, which if encountered would increase their fuel oil consumption
  • the development of more fuel efficient ship engines and propellers
  • building larger ships that can carry more cargo thereby reducing the number of ships required to carry the world’s cargo