Shipping is one of the least environmentally damaging forms of commercial transport; there has been a substantial reduction in marine pollution over the last 15 years, especially with regard to the amount of oil spilled into the sea, again despite a massive increase in world seaborne trade.
Figure 6 - Shipping and the Environment Source: Group of Experts on the Scientific Aspects of Marine Pollution (GESAMP)
It is estimated that land based discharge (sewage, industrial effluent and urban/river run off etc.) and atmospheric inputs from land industry sources account for some 77% of marine pollution generated from human activities. In contrast, maritime transport is only responsible for some 12% of the total and further reduction of this figure is vigorously pursued.
Maritime incidents do, of course, unfortunately happen from time to time and, when they do, they may result in loss of life and damage to the environment. However, every occasion in which a ship –
any ship – becomes involved in a pollution incident or a major casualty must be set against the literally billions of trouble-free, clean and economically efficient tonne-miles that shipping achieves every day, and all the consequent benefits that accrue from this activity.
Ship-generated water pollution
Definition: (a) Tonnes of harmful substances discharged into the sea operationally or accidentally from ships subject to IMO instruments.
Definition: (b) Number of spills occurring from ships subject to IMO instruments.
As directed by the Council (C/ES.23/D, paragraph 7.2 and 7.3), the Secretariat is examining the availability of statistics to monitor the strategic direction related to the impact of shipping on the environment, in particular for those indicators on which reporting against performance has not previously been possible owing to insufficient and relevant data sources. Appropriate proposals on such data sources will be submitted to a future session of the Council.
Definition: (c) Ratio of oil (cargo and bunkers) discharged into the sea, to total quantities carried by sea.
Figure 7 - Number of spills over 7 tonnes, but less that 700 onnes
Number of spills over 7 tonnes, but less than 700 tonnes
Source: ITOPF Annual Statistics Figure 8 - Number of oil spills over 700 tonnes Number of oil spills over 700 tonnes
Ship generated air pollution
The shipping industry is also a relatively small contributor to the total volume of atmospheric emissions compared to road vehicles and public utilities such as power stations while atmospheric pollution from ships has reduced in the last decade. There have been significant improvements in engine efficiency. Improved hull design and the use of ships with larger cargo carrying capacities have led to a reduction in emissions and an increase in fuel efficiency. Moreover, a new annex to IMO’s
MARPOL Convention (Marine Pollution Convention) entered into force in 2005 year, setting formal limits on sulphur oxide (SOx) and nitrogen oxide (NOx) emissions from ship-generated (bunkers or engine) exhausts and prohibiting deliberate emissions of ozone-depleting substances.
Figure 10 - comparison of CO2 emissions between different transport modes
In the future, improvements in hull design are expected to lead to further reductions in fuel oil consumption with consequent reductions in air pollution. The latest marine engines give a 30%-40% reduction in discharges of nitrogen oxide, with reductions of 60% likely in the future.In those sectors where it competes directly with other means of transport, shipping remains by far the most energy efficient. Research undertaken by the United Kingdom Government, for example, has demonstrated that energy consumption of road transport by truck lies in the range 0.7 to 1.2 Megajoules/tonne-km. By comparison, the consumption of a 3,000 dwt coastal tanker at 14 knots is about 0.3 Mj/tonne-km and that of a medium-size containership at 18.5 knots is about 0.12 Mj/tonne km.
