Air Pollution and GHG Emissions from Oceangoing Ships

In a world of global supply chains and rapidly expanding trade, ocean shipping—currently the dominant mode of transport for international cargo—is becoming an increasingly important source of air pollution and greenhouse gas emissions.

Today, ocean-going vessels transport 90 percent of all trade by volume to and from the 25 members of the European Community (EC), and nearly 80 percent by weight of all goods shipped in and out of the United States. Over the last three decades, activity in the marine shipping sector, as measured in metric ton-kilometers, has grown on average by 5 percent every year. Since emissions from ocean-going vessels have only been moderately controlled, this growth has been accompanied by a commensurate increase in the sector’s contribution to local and global air pollution.
Relative to other sectors, the regulation of commercial marine vessels represents a significant political and legal challenge as ships operate largely outside of national boundaries. Ocean-going vessels are mainly subject to oversight by the International Maritime Organization(IMO), under the purview of the United Nations.Unfortunately, IMO efforts to mitigate environmental impacts of emissions from global shipping have not kept pace with the industry’s growth and the evolution of control technologies for controlling emissions. The international process for establishing new regulatory requirements is further complicated by the complex relationships that exist between those nations to which most ships are registered under so-called“flags of convenience” and the large shipping in-terests (typically headquartered in other nations) that own most of the ships. As a result, the IMO adopted standards in 1997 that represented only a modest improvement in emissions from un-regulated engines. When these standards entered into force they reflected levels already achieved by the average in-use engine. The IMO’s current fuel sulfur limit of 4.5 percent is almost twice the average sulfur content of fuels in use in ships today and several thousand times the sulfur level of fuels used on-road in Europe and NorthAmerica. These standards at best codify the industry’s existing practices.
Under these circumstances, accelerated adoption of cleaner marine fuels and wider deploy-ment of existing pollution control technologies and emission reduction strategies could dramatically improve the environmental performance of the shipping sector. To explore these opportunities, the ICCT undertook a review of the status of pollution control measures and programs implemented to date throughout the world. This report describes the results of the ICCT review,focusing on the emission-reduction potential,feasibility, costs, and cost- effectiveness of avail-able environmental mitigation measures for the shipping sector. It also analyzes the legal context within which local, regional, and international programs can be developed. The report concludes with a series of policy recommendations aimed at achieving steady, incremental progress towards reducing emissions from marine vessels that will result in significant environment and public health benefits.