On October 10, the 57th session of the International Maritime Organization's (IMO) Marine Environment Protection Committee (MEPC) concluded without any action on a plan for regulations to control GHG emissions from ocean-going ships. The maritime shipping industry accounts for between 3 and 4 percent of the world's GHG emissions; emissions from that sector are expected to double in the next two decades. The IMO, a specialized agency of the United Nations, has been considering issues related to maritime GHG emissions since at least 2000, and one of the agenda items for the October meeting was discussion of GHG controls for ocean-going vessels.

Two primary issues stalled discussion on GHG regulations: whether GHG controls should apply equally to all ships, regardless of their flag state, or only to those ships flying the flags of more developed nations; and the possible use of market-based regulatory instruments (such as a cap-and-trade system) to control GHG emissions. It is now unclear whether the IMO will meet its stated goal of having a proposal for GHG regulations ready for presentation at the 2009 climate summit in Copenhagen.

One significant accomplishment did come out of the meeting: the unanimous adoption of an amendment to MARPOL Annex VI, which limits other harmful emissions from ships. The amendment places more stringent limitations on the emissions of sulfur oxides (SOx) and nitrogen oxides (NOx). In July 2008, President Bush signed the Maritime Pollution Protection Act of 2008, which implemented the previous version of Annex VI in the United States, and paved the way for the U.S.'s participation in the most recent round of meetings.