Outcomes of the Marine Environment Protection Committee (MEPC 83)

The Marine Environment Protection Committee (MEPC) met for its 83rd session in person at IMO Headquarters in London from April 7-11, 2025. The meeting was chaired by Dr. Harry Conway (Liberia), with Mr. Hanqiang Tan (Singapore) as Vice-Chair.

Highlights included:

Tackling climate change

• The Committee finalized and approved the draft legal text for the "IMO Net-Zero Framework," to be included as a new chapter in Annex VI to the International Convention for the Prevention of Pollution from Ships (MARPOL).
• The IMO Net-Zero Framework includes a set of "mid-term measures" aimed at reducing greenhouse gas emissions from international shipping, in line with the reduction targets set out in the 2023 IMO GHG Strategy. These measures consist of a technical and an economical element. 
• The Committee agreed that in the period between the adoption of the IMO Net-Zero Framework and its entry into force, further assessment (qualitative and quantitative, as appropriate) of the potential impacts of an increase in maritime transport costs on food security resulting from the adopted framework should be conducted.

Review of the short-term GHG reduction measures 

• The Committee finalized Phase 1 of the review of IMO's short-term GHG reduction measures, which were adopted in 2021 and entered into force in 2022. Key elements of the short-term measures include: Energy Efficiency Existing Ship Index (EEXI), enhanced Ship Energy Efficiency Management Plan (SEEMP), and Carbon Intensity Indicator (CII) rating scheme.
• Additionally, the Committee took the following actions:
  • Carbon intensity (CII) reduction factors for 2027-2030 – amendments adopted
  • Access to the IMO Data Collection System for ship fuel consumption – amendments approved
  • Workplan for Phase 2 of the review of short-term GHG reduction measures agreed
  • Ship Energy Efficiency Management Plan (SEEMP) framework – amendments adopted

Report on the annual carbon intensity and energy efficiency of the fleet

• The Committee noted the report by the IMO Secretariat on the carbon intensity of the international shipping fleet for the year 2023 (both demand- and supply-based), including a summary of carbon intensity developments of the fleet from 2019 to 2023. 

Onboard Carbon Capture and Storage (OCCS) and other energy efficiency matters

• The Committee approved a work plan on the development of a regulatory framework for the use of onboard carbon capture and storage (OCCS).
• The Committee adopted new Guidelines for testbed and onboard measurements of methane (CH4) and/or nitrous oxide (N2O) emissions from marine diesel engines.
• The Committee re-established the Correspondence Group on Measurement and Verification of Non-CO2 GHG Emissions and Onboard Carbon Capture, and tasked it with the following:
  • further develop the framework for the measurement and verification of actual methane (CH4) and nitrous oxide (N2O) emission factors and fuel slippage values for marine diesel fuels;
  • develop a regulatory framework for the use of onboard carbon capture and storage using the approved work plan; and
  • submit a written report to MEPC 84.

Addressing marine plastic litter 

• The Committee adopted the 2025 Action Plan to Address Marine Plastic Litter from Ships (2025 Action Plan) agreed by the Sub-Committee on Pollution Prevention and Response (PPR 12), and approved updated groupings of short-, mid- and long-term actions under this plan.
• With regard to the carriage of plastic pellets in freight containers by sea, the Committee noted that PPR 12 included a dedicated action for the development of mandatory measures to reduce the environmental risks of plastic pellets transported by sea in freight containers in the above 2025 Action Plan.

North-East Atlantic Ocean Emissions Control Area approved and Particularly Sensitive Sea Areas off Peru agreed in principle

• The Committee approved a proposal to designate the North-East Atlantic Ocean as an Emissions Control Area for Sulphur oxide emissions (SOX), particulate matter (PM) and nitrogen oxide emissions (NOX). The associated draft amendments to MARPOL Annex VI will be submitted to the extraordinary MEPC session in October 2025, with a view to adoption as part of the revised MARPOL Annex VI.
• The Committee agreed in principle to the designation of the "Reserva Nacional Dorsal de Nasca" (Nasca Ridge National Reserve) and the "Reserva Nacional Mar Tropical de Grau" (Grau Tropical Sea National Reserve) as Particularly Sensitive Sea Areas (PSSAs).

Review of the Ballast Water Management Convention 

• The Committee continued its ongoing review of the Ballast Water Management (BWM) Convention, including stocktaking of the progress made and consideration of the way forward with regard to the overall plan for completion of the review, with some high-level decisions needed to facilitate the achievement of the review targets.

Air pollution prevention 

• Exhaust Gas Cleaning Systems (scrubbers)

  • The Committee noted an update from the Sub-Committee on Pollution Prevention and Response (PPR) on regulating the discharge from EGCS or "scrubbers."

• Black Carbon emissions

  • The Committee noted the ongoing work on the concept of "polar fuels" (fuels that are most suitable for use in the Arctic to minimize environmental impact) and extended the target completion year for this output to 2027, to allow additional time to further develop the concept.

• Nitrogen Oxide (NOx) emissions

  • The Committee adopted the 2025 Guidelines on Selective Catalytic Reduction (SCR) Systems. SCR systems are active emission control technology systems used to reduce NOx emissions.

Amendments to NOx Technical Code adopted

• The Committee adopted amendments to the NOx Technical Code 2008 related to the following:
  • use of multiple engine operational profiles for a marine diesel engine, including clarifying engine test cycles (expected entry into force 1 March 2027);
  • certification of an engine subject to substantial modification or being certified to a tier to which the engine had not been certified at the time of its installation (expected entry into force 1 September 2026).

Pollution prevention and response

• The Committee considered and approved the report of the Sub-Committee on Pollution Prevention and Response (PPR12) and took the following actions:
  • approved Interim guidance on the carriage of blends of biofuels and MARPOL Annex I cargoes by conventional bunker ships;
  • approved Guidance on in-water cleaning of ships' biofouling; and
  • adopted amendments to the 2023 Guidelines for the development of the Inventory of Hazardous Materials, clarifying the relevant threshold in respect to cybutryne when samples are taken directly from the hull or from wet paint containers. The inventory is a key requirement under the Hong Kong International Convention for the Safe and Environmentally Sound Recycling of Ships.

Reports from other Sub-Committees approved

• The Committee, having approved the reports of the Sub-Committees on Carriage of Cargoes and Containers (CCC 10) and Implementation of IMO Instruments (III 10), and considered action requested of it by the Sub-Committee on Ship Design and Construction (SDC 11), took the following specific actions:
  • Casualty analysis reports and derived statistics
  • Draft Code on Alerts and Indicators, 2025

New outputs approved

• The Committee approved the following proposals for new outputs:
  • Development of a legally binding framework for the control and management of shipsʹ biofouling to minimize the transfer of invasive aquatic species;
  • Assessment of the implementation of the Hong Kong Convention through an experience building phase and development of clarifications and amendments to the Convention;
  • Review and amendment of the NOX Technical Code 2008 to provide a means for certification of engines that operate on non-carbon-containing fuel or mixtures of carbon-containing and non-carbon-containing fuels; and
  • Development of guidelines for the management of ammonia effluent generated by ships using ammonia as fuel.