The 84th Session of the IMO's Marine Environment Committee wasn’t just about the Net Zero Framework. The Committee also advanced a series of decisions that will directly affect ship operations — from ballast water management and plastic pellet carriage to underwater radiated noise and a new Emission Control Area in the North Atlantic. These issues may be less high profile than decarbonisation, but they are moving fast and will shape what ships need to do in practice over the coming years. This article breaks down what changed, what’s coming next, and what BIMCO is doing to support members.
Outcomes of MEPC 84
If you are seeking news and updates on the Net Zero Framework, we will publish a more thorough report once we have had time to reflect on the outcomes, the key points for members and the way forward.
Amendments to the BWM Convention and revised Guidelines for ballast water management plans (BWMPs)
Ballast water management was a key topic at MEPC 84, with the Committee advancing the ongoing review of the Convention and associated instruments.
The Committee approved draft amendments to the BWM Convention. The Secretariat will now prepare the consolidated revised Annex to the BWM Convention which is expected to be adopted at MEPC 85 later in 2026.
The draft amendments to the BWM Convention focus on strengthening implementation by clarifying and enhancing existing provisions rather than introducing new regulatory concepts. In particular, the revisions address the application of contingency measures, improve the content and approval of BWMPs, and introduce more explicit expectations on crew familiarisation and system maintenance, including record-keeping. The amendments also refine survey and certification provisions and provide greater clarity on the transition from prototype (D-4) systems to full D-2 compliance. Overall, the changes aim to improve consistency, transparency and practical application of the Convention in real-world operations.
We will provide BIMCO members with a detailed overview of the amendments to the BWMC and guidance on their practical application once adopted.
In parallel, the Committee adopted the revised 2026 Guidelines for ballast water management (BWM) and development of Ballast Water Management Plans (G4), which are intended to align with the amended Convention requirements and provide clearer and more consistent direction on the development and approval of ship-specific plans. The objectives of these Guidelines are to assist Governments, appropriate authorities, ships masters, operators and owners, and port authorities, as well as other interested parties, in preventing, minimizing and ultimately eliminating the risk of introducing harmful aquatic organisms and pathogens from ships' ballast water and associated sediments while protecting ships’ safety in applying the BWM Convention.
The revised Guidelines will apply from the date of entry into force of the Convention amendments, at which point existing Guidelines will be revoked. Until then, current Ballast Water Management Plans (BWMPs) remain compliant. However, the early adoption of the revised Guidelines is intended to provide Administrations and companies with sufficient time to review and update their BWMPs in preparation for the new requirements. BIMCO members may therefore wish to begin assessing potential updates to their plans at an early stage.
We will make the revised Guidelines on ballast water management and plans available to members once finalised by the IMO Secretariat, together with a summary of the key changes.
Work on the BWM Systems Code, including testing requirements, remains ongoing and will continue intersessionally. More broadly, discussions at the session highlighted an increasing focus on implementation challenges, including system performance in challenging conditions and the need for greater consistency in application.
At MEPC 85, the entry into force of the BWM Convention amendments will be determined and is expected to be concurrent with that of the amendments to the BWMS Code, depending on when the latter are also completed
Carriage of plastic pellets in freight containers
The carriage of plastic pellets continued to be a divisive topic with member states failing to reach a decision on under which IMO Convention (MARPOL, SOLAS or both) a code on plastic pellet carriage would be made mandatory. Nonetheless, the Committee instructed the Pollution Prevention and Response Sub-Committee (which will meet for its 14th session in early 2027) to develop the draft code noting that the text of the code is likely to be the same regardless of where it sits as well as developing potential consequential amendments to MARPOL and/or SOLAS with MEPC then making a policy decision at a future session. At BIMCO we support that any code should provide the same operational clarity and environmental protection that would be enabled by the allocation of a UN number and resulting carriage in accordance with the provisions of the International Maritime Dangerous Goods (IMDG) code- and this should happen without delay.
To inform our input into discussions at PPR we would urge any members with experience in applying the IMO Guidelines on the carriage of plastic pellets by sea in freight containers to get in touch. Underwater radiated noise (URN)
The Committee approved an extension of the Experience Building Phase on URN to 2028 which had been supported by BIMCO noting that
- Uptake of the 2023 revised guidelines is still at an early stage
- More time is needed to gather sufficient, reliable data
- Industry needs space to understand what measures are effective, feasible
In spring 2024, we launched a survey to track the number of ships that have adopted the revised guidelines. The survey, initiated by BIMCO, ICS and INTERTANKO, will help the shipping industry show progress in adapting to mitigating measures, even without mandatory IMO requirements on URN.
In addition, the Committee considered the development of a policy road map which would clarify immediate needs during the two-year EBP extension and outline the IMO’s mid-term policy priorities and long-term approaches to further prevent and reduce URN. We therefore expect proposals to be discussed at MEPC 85. The Committee also agreed to an IMO-commissioned study on URN emissions whilst recognising that there is a need to identify and secure the necessary financial resources. And finally, they approved the draft MEPC circular on the technical guidance on co-optimizing energy efficiency and underwater radiated noise at the design and retrofit stage. The purpose of this circular is to provide supplementary technical guidance to support the integration of URN reduction measures with energy efficiency considerations during ship design and retrofitting. Specifically, it seeks to clarify potential trade-offs between URN mitigation and conventional propeller design, and to promote co-benefits between quiet ship technologies and clean energy performance objectives.
The circular on energy efficiency and URN will be made available to members when published by the IMO.
Adoption of mandatory instruments
MEPC 84 adopted several amendments to MARPOL Annex VI, including clarifications to data reporting under Regulations 27 and 28, the designation of a new Emission Control Area in the North East Atlantic, and provisions on the use of multiple engine operation profiles.
Designation of the North-East Atlantic as an Emission Control Area
MEPC adopted the resolution that sees the designation of the North-East Atlantic as a new emission control area (ECA) for Nitrogen Oxides (NOX), Sulphur Oxides (SOX) and particulate matter. The ECA will come into effect on 1 September 2027.
The new ECA prohibits ships from using fuel with a sulphur content greater than 0.10% m/m, or achieve equivalent emission reductions using approved technology, and requires all ships constructed after a certain date to comply with NOXTier III limits as specified in Reg.13 of MARPOL Annex VI.
For ships constructed on or after 1 January 2027 and operating in the North-East Atlantic Emission Control Area the following regulation with regards to NOX Tier III will apply. A "ship constructed on or after 1 January 2027" means a ship:
- For which the building contract is placed on or after 1 January 2027 or
- In the absence of a building contract, the keel of which is laid or which is at a similar stage of construction on or after 1 July 2027 or
- The delivery of which is on or after 1 January 2031."
The North-East Atlantic Emission Control Area (NE Atlantic ECA) includes the Exclusive Economic Zones (EEZ) and territorial seas, extending up to 200 nautical miles from the baselines, of Greenland, Iceland, the Faroe Islands, Ireland, and the mainland of the United Kingdom, of France, of Spain, and of Portugal.
Collection and reporting of ship fuel oil consumption data
The amended regulation 27 of MARPOL will enter into force on 1 September 2027 and will provide for the collection, management, and controlled sharing of ship fuel oil consumption data through the IMO Ship Fuel Oil Consumption Database. The IMO grants Administrations, or organizations authorized by them, access to all reported data for their respective ships for previous calendar years.
Parties to the MARPOL Convention Annex VI will be granted access to a non anonymized dataset covering all ships subject to the regulation, strictly for analytical and consideration purposes. At the same time, the IMO maintains an anonymized version of the database to ensure that individual ships cannot be identified and facilitates access for public users.
Under the revised regulation, the IMO is responsible for the operation and management of the database in accordance with IMO guidelines. On an ad hoc basis, the IMO may share data with analytical consultancies and research entities, subject to strict confidentiality requirements.
Use of multiple engine operational profiles and clarification of engine test cycles
MEPC 84 adopted revised definitions, certification documentation, and NOX engine test cycles under MARPOL Annex VI to clarify how marine diesel engines are tested and certified, including when multiple engine operational profiles are used.
Amendments to the IAPP Certificate (Appendix I) includes new rows added to the Supplement to the International Air Pollution Prevention (IAPP) Certificate to allow recording of compliance using NTC 8 (Multiple Engine Operational Profiles).
Appendix II – Test Cycles and Weighting Factors has been fully replaced to clarify and standardise which test cycles apply to different engine and propulsion types when demonstrating compliance with NOX limits under regulation 13.
EEDI for ships equipped with a dual-fuel main or auxiliary engine
MEPC 84 adopted amendments to the 2022 Guidelines on the Method of Calculation of the Attained Energy Efficiency Design Index (EEDI), together with new 2026 Guidelines on survey and certification of the EEDI.
The revised guidelines clarify how the attained EEDI should be calculated for ships equipped with dual‑fuel main and/or auxiliary engines, including LNG‑fuelled engines, and how compliance is to be surveyed and certified. The changes aim to provide greater consistency and certainty for shipowners when building ships with dual‑fuel engines.
Continue to use the total distance travelled for CII calculations
MEPC 84 adopted amendments to the 2024 Guidelines for the development of a Ship Energy Efficiency Management Plan (2024 SEEMP Guidelines) in relation to increased granularity of data submitted annually to the IMO Data Collection System (IMO DCS).
MEPC 84 also adopted amendments to the 2022 Guidelines on operational carbon intensity indicators (CII) and the calculation methods. The amendments stress that transport work (W) for now continue to be defined as the product of a ship’s capacity (DWT or GT as applicable) and the total distance travelled (both under way and not under way) in a given calendar year. Shipowners and ship managers should therefore continue to use total distance travelled, and fuel oil consumption data from total distance travelled, when calculating a ship’s attained CII, until IMO makes a decision on whether to base the CII on fuel consumption while under way.
Interim guidance approved on the use of biofuels in relation to IMO DCS and CII
MEPC 84 approved a revised MEPC circular containing interim guidance on the use of biofuels under regulations 26, 27 and 28 of MARPOL Annex VI.
The revised guidance clarifies that, for biofuels blended with fossil fuel, the CO2 Emission Conversion Factor (Cf) should be calculated as a weighted average based on the mass of the fuels blended, rather than on an energy basis.
Biofuels, or the biogenic components within biofuel blends, that are not certified as ʺsustainableʺ or do not meet the well-to-wake (WtW) emission factor criteria set out in the Guidelines on life cycle GHG intensity of marine fuels (LCA Guidelines) should, in their entirety, be assigned a Cf equal to that of the equivalent fossil fuel type.
For the purpose of consistent annual reporting to the IMO Data Collection System (IMO DCS), shipowners, charterers and ship managers should be aware that the revised guidance on biofuels will apply from 1 January 2027.
Quantification of Methane (CH4) and Nitrous Oxide (N2O) emissions
The 2023 IMO Strategy on reduction of GHG emissions from ships specify that IMO should work to reduce emissions of methane (CH4) and nitrous oxide (N2O), both of which are greenhouse gases (GHG).
In this context, MEPC 84 adopted three guidelines:
- 2026 guidelines for test-bed and onboard measurements of methane (CH4) and/or nitrous oxide (N2O) emissions from marine diesel engines, which supersede the previous version of these guidelines
- New guidelines for engine load monitoring (ELM) and calculation of emission values (ELM Guidelines)
- New guidelines for continuous emission monitoring systems (CEMS) used to quantify methane (CH4) and/or nitrous oxide (N2O) emissions from marine diesel engines.
The ELM guidelines specify the method to establish factors that reflect the actual operation of a marine diesel engine using engine load monitoring, and for the calculation of emission values. The ELM may be used to monitor actual engine load during operation instead of the pre-defined weighting factors set out in section 3.2 of the NOX Technical Code 2008 and is intended to be used in combination with verified CH4 and N2O emission measurements to derive more representative emission values.
The CEMS guidelines provide a uniform framework for the onboard measurement and mass basis quantification of the emissions of methane and nitrous oxide emissions from marine diesel engines using continuous emission monitoring systems.
MEPC 84 agrees that for now on a voluntary basis actual tank-to-wake (TtW) emission values for methane and nitrous oxide emissions may be quantified, using the following approaches:
- Engine load monitoring, using the new ELM Guidelines, in conjunction with the 2026 Guidelines for test bed and onboard measurements of CH4 and/or N2O emissions from marine diesel engines, and/or
- Continuous emissions measurement system, using the new CEMS Guidelines.
The IMO encourages voluntary measurements and studies using the three guidelines and the sharing of information to support the further work of the Marine Environment Protection Committee (MEPC).
Attention on biodiversity beyond national jurisdiction
The Committee began to lay the groundwork as to how it will work in relation to the Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction (BBNJ Agreement) which entered into force in January 2026. We believe this is an important step as early clarity on the relationship between the IMO and the BBNJ Agreement is essential for ensuring that the realities of ship operations and the existing regulatory regimes are considered.
We will be undertaking membership engagement activities related to the BBNJ Agreement and we would encourage members to reach out to learn more.
Photo: “Marine Environment Protection Committee (MEPC 84)” by International Maritime Organization, CC BY 4.0
