International Maritime Organization GHG

The International Maritime Organization (IMO) is the UN specialized agency responsible for regulating international shipping, including its greenhouse gas (GHG) emissions. International shipping accounts for roughly 3% of global GHG emissions, and because emissions from international bunker fuels fall outside national inventories under the UNFCCC, the IMO has become the primary forum for governing them.

The IMO's GHG work is centered in the Marine Environment Protection Committee (MEPC) and operates principally through Annex VI of the MARPOL Convention. Key instruments include:

• The Energy Efficiency Design Index (EEDI), adopted in 2011, which sets mandatory efficiency standards for new ships.
• The Ship Energy Efficiency Management Plan (SEEMP), required for all ships above 400 gross tonnes.
• The Data Collection System (DCS) for fuel oil consumption, in force since 2019.
• The Energy Efficiency Existing Ship Index (EEXI) and Carbon Intensity Indicator (CII), which entered into force in November 2022.

In 2018, the MEPC adopted the Initial IMO Strategy on Reduction of GHG Emissions from Ships, targeting at least a 50% cut in annual GHG emissions by 2050 compared to 2008. This was superseded by the 2023 IMO GHG Strategy, adopted at MEPC 80 in July 2023, which raised ambition to net-zero GHG emissions from international shipping by or around 2050, with indicative checkpoints of roughly 20–30% reduction by 2030 and 70–80% by 2040 (relative to 2008).

In April 2025, MEPC 83 approved a draft "IMO Net-Zero Framework" combining a global fuel standard with a GHG pricing mechanism, slated for formal adoption in October 2025 and entry into force in 2027. If adopted, it would be the first sector-wide mandatory emissions pricing system at the global level.

Debates persist over the principle of Common But Differentiated Responsibilities (CBDR), the treatment of developing states, and revenue use from any levy.