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IMO MARPOL Convention

The International Maritime Organization is a UN body for international shipping.

International shipping represents a substantial and growing source of emissions of air pollutants, including greenhouse gases. Emissions of air pollutants from international shipping are regulated by Annex VI to the International Convention on the Prevention of Pollution from Ships (MARPOL), which was originally signed in September 1997 and came into force in May 2005. Annex VI sets limits on the sulphur content of marine fuel oils and on the emissions of nitrogen oxides (NOx) from new ship engines.

However, the 1997 standards are so weak as to be hardly likely to have any appreciable effect, and on 9 October 2008 the IMO's Marine Environment Protection Committee (MEPC) agreed to revise and strengthen the emission standards in Annex VI. The revised law will enter force in July 2010.

The current global limit on sulphur in marine fuels is 4.5 per cent. Under the revised Annex this limit will fall in two stages to 3.5 per cent in 2012, and finally to 0.5 per cent in 2020 subject to a review in 2018. As an alternative to use low-sulphur fuels, ships are allowed to use exhaust gas cleaning systems (e.g. scrubbers) or use other methods to limit their sulphur emissions.

Annex VI also sets a limit of 1.5 per cent sulphur for marine fuel oil used by ships sailing in designated Emission Control Areas (ECAs) – the Baltic Sea was the first ECA to enter into force in 2006, followed by the North Sea in 2007. The revised Annex VI lowers the sulphur limit in ECAs to 1.0 per cent from July 2010 and to 0.1 per cent as from 2015.

Emissions of NOx are controlled by emission standards for new ship engines. The Tier I standards apply to all new engines as from January 2000, but these are so weak that in practise they do not have any appreciable effect. The revised Annex sets new Tier II standards that apply from 2011 and will cut emission by 16-22 per cent (relative to Tier I). It also sets Tier III standards that will cut emissions from new engines by about 80 per cent (relative to Tier I), but the Tier III standards will apply only in the specially designated emission control areas (ECAs).

The IMO has been considering how to reduce greenhouse gas (GHG) emissions since before 2000, when it received a report estimating those emissions and describing various potential measures to reduce them. So far, however, the IMO has failed to make any significant progress in talks on addressing GHG emissions from shipping. Progress has been thwarted mainly by the opposition of developing countries (non-Annex I countries under the Kyoto Protocol) to any IMO initiative on climate change that fails to respect the principle of "common but differentiated responsibilities".

Air Pollution & Climate Secretariat, Box 7005, SE-402 31 Göteborg, Sweden.
Phone. +46-31-711 45 15, Fax +46-31-711 46 20, info@airclim.org

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