From UNFCCC 1992 through MARPOL Annex VI, CII, EEXI, the 2023 GHG Strategy, and the Net-Zero Framework. Three layers of detail — including Marine Engineer Notes.
30+Milestones
1992–2050Coverage
3Detail Layers
Category
UN / UNFCCC
IMO / MEPC
MARPOL Annex VI
GHG Studies
Net-Zero Framework
EU Instruments
Future Checkpoints
Era
Mode
EEDIEnergy Efficiency Design Index — technical standard for new ships
EEXIEnergy Efficiency Existing Ship Index — one-off compliance for existing ships
WTWWell-to-Wake — full lifecycle GHG accounting from fuel production to combustion
TTWTank-to-Wake — combustion emissions only, excludes upstream production
OCCSOn-board Carbon Capture and Storage — methodology under IMO development
EPLEngine Power Limitation — primary EEXI compliance method via governor seal
Parallel instruments — same objective, different jurisdiction
Item
FuelEU Maritime
IMO GFI (NZF)
Regulator
European Union
IMO (MARPOL Annex VI)
Scope
EU port calls & voyages
Global — all ships ≥5,000 GT
In force
1 January 2025
Target: 1 January 2028
Baseline year
2020
2008
Reference value
~91.16 gCO₂eq/MJ (2020)
93.3 gCO₂eq/MJ (2008)
Accounting method
Well-to-Wake (WTW)
Well-to-Wake (WTW)
Enforcement mechanism
Financial penalty to verifier
Remedial Units — pay into IMO fund
ZNZ / reward tier
No reward mechanism
ZNZ ≤19.0 gCO₂eq/MJ receives credits
2030 reduction target
−6% vs 2020 baseline
−20% total GHG vs 2008 (indicative)
2050 target
−80% vs 2020
Net-zero by/around 2050
OPS (onshore power)
Mandatory in EU ports by 2030
Not covered
No matching events found.
Foundations & Early Studies · 1992–2009
1992
UNFCCC Adopted — Rio Earth Summit
Foundational legal instrument for all international climate action. Shipping GHG responsibility placed under IMO via Kyoto Protocol Article 2.2.
The United Nations Framework Convention on Climate Change (UNFCCC) was adopted at the Rio Earth Summit. Under Article 2, it set the objective to stabilise GHG concentrations. International shipping GHG was excluded from the Kyoto Protocol (Article 2.2), placing responsibility on IMO.
This is the root legal instrument from which all maritime decarbonisation obligations flow.
Oral exam angle: When asked about the legal basis for IMO GHG rules, trace it to UNFCCC 1992 → Kyoto Protocol Art. 2.2 → MARPOL Annex VI Chapter 4. This lineage shows the examiner you understand why IMO has jurisdiction, not just what the rules are.
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1997
Kyoto Protocol & MARPOL Annex VI Adopted
Kyoto assigns shipping GHG to IMO. MARPOL Annex VI adopted — first international air pollution rules creating the regulatory vehicle for all future GHG measures.
The Kyoto Protocol (Article 2.2) assigned responsibility for controlling shipping GHG emissions to IMO. In the same year, MARPOL Annex VI (Prevention of Air Pollution from Ships) was adopted, focusing initially on SOx, NOx, and ODS — creating the legal vehicle within which GHG rules (Chapter 4, 2011) would later be embedded.
Kyoto ProtocolMARPOL Annex VI
Ref: Kyoto Protocol Art. 2.2 | MARPOL Annex VI 1997
Marine Engineer Notes
Oral exam angle: MARPOL Annex VI 1997 addressed SOx and NOx only — CO₂ was not regulated. Examiners test whether candidates understand that GHG rules came 14 years later via Chapter 4 (2011). The Annex was the framework; Chapter 4 was the GHG content.
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2000
1st IMO GHG Study Published
Shipping confirmed at ~1.8% of global CO₂ (~430 Mt/yr, 1996 data). First scientific baseline for all subsequent IMO regulatory work.
IMO published its first comprehensive study on GHG emissions from ships — estimating international shipping contributed ~1.8% of global anthropogenic CO₂ emissions (~430 million tonnes CO₂/yr in 1996). This was the first scientific foundation for IMO's regulatory trajectory.
GHG StudyCO₂ Baseline1st Study
Ref: First IMO GHG Study, 2000
Marine Engineer Notes
Context to retain: Five GHG studies have now been commissioned — 2000, 2009, 2014, 2020, and 2026 (5th study, ToR finalised at MEPC 84). Each study recalculates shipping's share and informs tighter measures. Knowing the sequence shows an examiner you understand the evidence-based regulatory cycle.
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19 May 2005
MARPOL Annex VI Enters into Force
First mandatory international air pollution rules for ships — the regulatory vehicle within which Chapter 4 (GHG) would be embedded six years later.
MARPOL Annex VI entered into force on 19 May 2005, establishing mandatory regulations for SOx, NOx, and ODS from ships. It did not yet address CO₂. Entry into force created the legal mechanism within which Chapter 4 (EEDI/SEEMP, 2011) would subsequently be inserted.
MARPOL Annex VIEIF 2005
Ref: MARPOL Annex VI, 19 May 2005
Marine Engineer Notes
IAPP Certificate: MARPOL Annex VI entry into force required ships to hold an International Air Pollution Prevention (IAPP) Certificate. This is the same certificate under which EEXI compliance is now recorded. Know your ship's IAPP Certificate — examiners ask about survey intervals and what endorsements it carries.
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2009
2nd IMO GHG Study & COP15 Copenhagen
Shipping at ~2.7% of global CO₂ (~870 Mt). Projections: 150–250% growth by 2050 without action. COP15 fails — pressure shifts fully to IMO.
The Second IMO GHG Study (2009) estimated international shipping emitted ~870 Mt CO₂ in 2007 (~2.7% of global). Projections showed 150–250% growth by 2050 without action. COP15 in Copenhagen failed to produce a binding global agreement, redirecting pressure entirely onto IMO to act independently.
2nd GHG StudyCOP15870 Mt CO₂
Ref: 2nd IMO GHG Study, 2009 | COP15 Copenhagen
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First Mandatory Measures · 2011–2018
July 2011
MEPC 62 — EEDI & SEEMP Adopted
Chapter 4 added to MARPOL Annex VI — the first mandatory global GHG measures for international shipping. EEDI for new ships, SEEMP for all ships.
EEDI (Energy Efficiency Design Index): Technical measure for new ships. Progressive Phase 0→3 reductions in CO₂/tonne-mile. Applied to 7 ship types initially; required values tighten by 30% by 2030 vs Phase 0.
SEEMP (Ship Energy Efficiency Management Plan): Operational measure — all ships ≥400 GT must develop and implement a SEEMP as part of their SMS. Not prescriptive on targets; focuses on systematic monitoring and improvement planning.
MEPC 62EEDISEEMPChapter 4
MARPOL Reg.Ref: MEPC 62, July 2011 | MARPOL Annex VI Reg. 20–22
Marine Engineer Notes
Onboard — SEEMP: The SEEMP must be kept onboard and available to PSC. It should include voyage planning practices, trim optimisation procedures, slow steaming policy, and waste heat recovery if fitted. SEEMP Part II (fuel oil data collection) and Part III (CII management plan) were added later.
MEO oral angle: "What is Chapter 4 of MARPOL Annex VI?" — EEDI (Reg. 20–21), EEXI (Reg. 23), CII (Reg. 26–28), SEEMP (Reg. 22). Know all four regulations by number and what they cover.
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2014
3rd IMO GHG Study
Shipping at ~2.2% of global CO₂ (~938 Mt, 2012 data). Confirmed DCS need for verified fuel data. Directly influenced MEPC 70's decision to mandate the IMO DCS in 2016.
The Third IMO GHG Study (2014) updated the emissions inventory: international shipping emitted ~938 Mt CO₂ in 2012 (~2.2% of global). Projections showed 50–250% growth by 2050 depending on economic and energy scenarios.
Crucially, the study highlighted the absence of a verified fuel data collection system — an evidence gap that strongly influenced IMO's decision to mandate the DCS (Data Collection System) at MEPC 70 in 2016. Without standardised verified fuel data, CII would have had no operational foundation.
3rd GHG Study938 Mt CO₂DCS Catalyst
Ref: Third IMO GHG Study, 2014 | MEPC 67
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December 2015
Paris Agreement — COP21
Global 1.5°C / 2°C climate target agreed by 196 parties. Created the political forcing environment that made MEPC 72's ambitious 2018 GHG Strategy politically possible.
The Paris Agreement (COP21, December 2015) committed parties to limiting global temperature rise to well below 2°C, pursuing 1.5°C. Shipping was not directly regulated under Paris — but the Agreement created the political environment in which IMO could no longer defer a meaningful GHG strategy. MEPC 72's 2018 Initial GHG Strategy was strongly influenced by the ambition level Paris had established.
COP21Paris Agreement1.5°C
Ref: Paris Agreement, UNFCCC, December 2015
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October 2016
IMO DCS Mandated — MEPC 70
Mandatory fuel oil consumption reporting for all ships ≥5,000 GT from 2018. The verified data pipeline that made CII operationally possible — without DCS, there is no CII.
MEPC 70 (October 2016) adopted amendments to MARPOL Annex VI adding Regulation 22A — the IMO Data Collection System (DCS). Ships ≥5,000 GT must collect and report annual fuel oil consumption data from 1 March 2018.
This is the invisible foundation of CII. Without standardised verified fuel data at fleet scale, the Carbon Intensity Indicator (adopted MEPC 76, 2021) cannot function. DCS is the data pipeline; CII is the output.
MEPC 70IMO DCSReg 22AFuel Data
MARPOL Reg.Ref: MEPC 70, October 2016 | MARPOL Annex VI Reg. 22A
Marine Engineer Notes
Onboard — DCS: The Chief Engineer is responsible for collecting and reporting fuel oil consumption data to the company's DCS system. Data is collected per voyage leg (fuel type, quantity, distance, hours underway). The SEEMP Part II documents the methodology. Data is verified by your flag state-approved verifier annually before submission to the IMO Ship Fuel Oil Consumption Database.
MEO oral angle: Examiners ask "How does CII work?" — start with DCS. Annual fuel consumption data (verified via SEEMP Part II) feeds the CII calculation. The rating is then reported on the SEEMP Part III and sent to the Administration.
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April 2018
MEPC 72 — Initial IMO GHG Strategy Adopted
Watershed session. IMO commits to ≥50% total GHG reduction by 2050 vs 2008, and phase-out ASAP. 2008 established as the universal baseline year for all subsequent instruments.
MEPC 72 (April 2018) adopted the Initial IMO Strategy — the first time IMO committed to absolute GHG reduction targets:
Carbon intensity: ≥40% reduction by 2030 vs 2008; strive for 70% by 2050 Total GHG: ≥50% reduction by 2050 vs 2008; pursue phase-out as soon as possible 2008 baseline: Confirmed as the universal reference year for all subsequent instruments (EEXI, CII, NZF)
The strategy mandated short-, mid-, and long-term measures and created the political architecture for everything that followed.
MEPC 72Initial GHG Strategy50% by 20502008 Baseline
Why 2008 matters: 2008 is the peak year in the shipping industry's emissions history — it was chosen precisely because it sets the most demanding baseline. When examiners ask why 2008 was selected, the answer is: it represents the highest pre-crisis emissions year and ensures targets are genuinely ambitious rather than starting from a depressed baseline.
MEO oral angle: The Initial Strategy is the parent document for EEXI, CII, and the NZF. All three short-term and mid-term measures are responses to mandates established at MEPC 72.
IMO–Norway partnership programme to support developing nations in implementing the Initial GHG Strategy. Operates through active technical workstreams: Ships & Port Efficiency, Alternative Fuels, and others — delivering practical implementation tools directly to flag states and industry.
GreenVoyage2050 is a joint IMO–Norway technical cooperation programme established to help developing countries and small island developing states (SIDS) implement the 2018 Initial IMO GHG Strategy. It operates through several active workstreams translating strategy into practical tools:
Ships & Port Efficiency Workstream: Focuses on reducing emissions through operational efficiency at sea and in port. Outputs include:
• Port Call Optimisation (PCO) Guide — practical guidance for ships, ports, and operators to reduce idle time, minimise anchor waiting, and improve berth scheduling coordination. 🔵 Class/Industry-reported
• Wind Propulsion Technology — draft submission covering wind-assisted propulsion as a viable decarbonisation pathway; currently under review. 📊 MIW Analysis
• Just-In-Time (JIT) Arrival Concept Pilot — piloting JIT concepts for FIFO (First-In-First-Out) ports to eliminate unnecessary high-speed transit followed by extended anchorage waiting. Significant fuel savings potential: studies suggest JIT arrival alone can reduce port-related emissions by 10–20%.
Why this matters: GreenVoyage2050 is the bridge between IMO strategy text and real-world implementation — particularly critical for flag states that lack the technical capacity to act unilaterally. The PCO Guide and JIT pilots directly address the operational efficiency gap that CII regulations expose but do not solve.
Scope: Partner countries across Asia-Pacific, Africa, Caribbean, and Pacific SIDS. Programme runs through IMO's Integrated Technical Cooperation Programme (ITCP).
PCO & JIT — the Chief Engineer's stake: Port call optimisation directly affects your fuel consumption record and, by extension, your CII rating. A vessel that transits at high speed only to anchor for 18 hours accumulates fuel burn with no cargo movement — the worst possible CII outcome. JIT arrival eliminates that dead mileage: the port authority communicates the berth-ready time and the vessel adjusts speed accordingly. The SEEMP Part I should document your company's JIT and slow steaming policy.
Wind Propulsion: Wind-Assisted Propulsion Systems (WAPS) — Flettner rotors, rigid sails, kite sails — are increasingly being fitted on bulk carriers and tankers. From a GFI perspective, the key question is how wind contribution is credited in the fuel intensity calculation. IMO methodology for this is still developing — watch MEPC circulars.
MEO oral angle: If asked about operational efficiency measures, structure your answer around the three pillars: (1) voyage planning and JIT arrival, (2) trim and hull optimisation, (3) auxiliary load management. GreenVoyage2050's PCO Guide formalises pillar one at an international level.
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1 January 2020
Global Sulphur Cap — 0.50% Global Limit / 0.10% ECA Limit
The most operationally significant MARPOL Annex VI change since entry into force. Global 0.50% S limit (from 3.5%) — required fleet-wide fuel management system changes overnight.
MARPOL Annex VI Regulation 14 reduced the global sulphur limit for fuel oil from 3.50% to 0.50% m/m from 1 January 2020. ECA limit remained at 0.10% m/m.
Compliance options: (1) switch to VLSFO/MGO, (2) fit an approved exhaust gas cleaning system (scrubber), (3) use LNG. This regulation directly accelerated investment in environmental compliance technologies — scrubbers, LNG propulsion, and VLSFO blending infrastructure — that the later decarbonisation framework builds upon.
Sulphur Cap0.50% GlobalMARPOL Reg. 14VLSFO
Ref: MARPOL Annex VI Regulation 14 | MEPC 70
Marine Engineer Notes
Onboard operational change: Vessels without scrubbers must carry VLSFO (≤0.50% S). Fuel changeover procedures must be documented in the Oil Record Book and the ship's Fuel Oil Changeover Procedure Manual. The Fuel Oil Non-Availability Report (FONAR) procedure applies if compliant fuel is unavailable at a port.
Scrubber operation: Open-loop scrubbers are prohibited in certain waters (Baltic, North Sea, some port state waters). The Chief Engineer must know the ship's scrubber compliance map and ECA entry/exit procedures.
MEO oral angle: Know Regulation 14 (sulphur), Regulation 13 (NOx), and Chapter 4 (GHG) as distinct regulatory structures within MARPOL Annex VI. Examiners frequently test whether candidates can differentiate between them.
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2020
4th IMO GHG Study (MEPC 75)
Shipping at ~2.89% of global CO₂ (~1,076 Mt, 2018 data). 2008 baseline confirmed at 93.3 gCO₂eq/MJ — this is the GFI reference value against which all NZF compliance is measured.
The Fourth IMO GHG Study (MEPC 75, 2020): international shipping emitted ~1,076 Mt CO₂ in 2018 (~2.89% of global). Without action, projections showed 90–130% growth by 2050 above 2008 levels.
Critically, the study confirmed the 2008 reference value for GFI calculations as 93.3 gCO₂eq/MJ (well-to-wake basis) — the figure against which all Net-Zero Framework compliance is measured.
MEPC 754th GHG Study93.3 gCO₂eq/MJ
Ref: 4th IMO GHG Study, MEPC 75, 2020
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June 2021
MEPC 76 — EEXI, CII & SEEMP III Adopted
The short-term measures package. EEXI (one-off technical threshold for existing ships), CII (annual A–E operational rating), SEEMP Part III (verified CII plan). Mandatory from 1 January 2023.
EEXI (Energy Efficiency Existing Ship Index — Reg. 23): One-off compliance for existing ships ≥400 GT. Engine Power Limitation (EPL) is the primary remedy. Unlike CII, EEXI is fixed at point of compliance — it does not change annually.
CII (Carbon Intensity Indicator — Reg. 26–28): Annual operational rating (A–E) for ships ≥5,000 GT. A D rating for three consecutive years, or an E rating for one reporting period, triggers a mandatory corrective action plan to be submitted to the Administration. Per MARPOL Annex VI / MEPC.339(77).
SEEMP Part III (Reg. 26): Verified CII management plan required for ships ≥5,000 GT. All entered into force: 1 November 2022. Mandatory compliance: 1 January 2023.
MEPC 76EEXICIISEEMP III
MARPOL Reg.Ref: MEPC 76, June 2021 | MARPOL Annex VI Reg. 23–28
Marine Engineer Notes
Onboard — EEXI: If your vessel was EPL-fitted, the shaft power limiter is a physical seal on the fuel rack or governor — cannot be removed without flag state approval. Know where it is, what its documented limit is, and which certificate records it (IAPP Certificate, Supplement).
Onboard — CII: Every tonne of fuel oil consumed is a data point in your annual rating. Slow steaming, trim optimisation, auxiliary load management, and waste heat recovery directly affect the A–E score. The Chief Engineer should understand the ship's CII trajectory and what operational levers move it.
SEEMP Part III: Kept onboard — PSC can request it. It must include the ship's annual CII required value, actual CII, rating, and a corrective action plan where required — mandatory if rated D for three consecutive years, or E for one reporting period (MARPOL Annex VI Reg. 26 / MEPC.339(77)).
MEO oral angle: "Difference between EEXI and CII?" — EEXI is a one-time design/technical threshold (like EEDI for existing ships); CII is a continuous operational performance metric reviewed annually. Both under MARPOL Annex VI Chapter 4.
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1 January 2023
First CII Rating Year Begins
First year of mandatory CII operational data collection for ships ≥5,000 GT. The fleet's first encounter with annual carbon intensity scoring as a compliance obligation.
EEXI, CII, and SEEMP Part III entered mandatory compliance on 1 January 2023. This was the first year shipping companies collected annual CII operational data with the knowledge that ratings would be formally reported and recorded.
First EEXI certification was required at the first IAPP Certificate annual or renewal survey on or after 1 January 2023. CII ratings from 2023 data were reported in 2024 — the first year where a D rating (for one year, building toward the three-consecutive-year trigger) or an E rating (triggering corrective action immediately after one reporting period) could formally require a corrective action plan.
CII Year 1EEXI ComplianceSEEMP III
Ref: MARPOL Annex VI Chapter 4 | MEPC.1/Circ.896
Marine Engineer Notes
Practical consequence: From 2023, CII rating is a commercial factor — charterers, financiers, and P&I clubs increasingly reference CII rating in contracts and cover terms. A persistent D/E rating creates commercial liability beyond regulatory non-compliance.
What the Chief Engineer controls: Fuel type selection (GHG factor per fuel), speed (cubic relationship to fuel consumption), trim (direct drag coefficient), waste heat recovery utilisation, and auxiliary load management. All feed directly into the annual CII calculation.
MEO oral angle: CII reduction factors tighten each year through to 2030. The required CII value becomes more demanding annually — a ship rated B today may be rated C or D in two years without operational improvement.
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2022–2023
EU ETS Extended to Maritime & FuelEU Maritime Adopted
EU creates the first hard financial penalty mechanism for shipping GHG on European trades. Phase-in: 40% coverage (2024) → 70% (2025) → 100% (2026). Key distinction: 2026 is the first 100% coverage year — allowances for 2026 emissions are reported in 2027 and surrendered by the applicable EU ETS deadline under EU Regulation 2023/957.
EU ETS (Emissions Trading System): Extended to maritime. Coverage phase-in: 40% (2024) → 70% (2025) → 100% (2026). Key distinction: 2026 is the first year of 100% emissions coverage — for 2026 emissions (reported in 2027), 100% allowance coverage applies, with allowances surrendered by the applicable EU ETS deadline under EU Regulation 2023/957. Reporting year and surrender year are distinct: a vessel's 2026 emissions are verified and reported in 2027, with allowances surrendered thereafter. Ships on EU trades must purchase and surrender EU Allowances (EUAs).
FuelEU Maritime (EU Reg 2023/1805): In force 1 January 2025. Requires vessels ≥5,000 GT on EU routes to reduce GHG intensity vs 2020 baseline on a Well-to-Wake basis. Reduction pathway: −2% (2025) → −6% (2030) → −14.5% (2035) → −80% (2050). Prevents gaming via nominally zero-carbon fuels with carbon-intensive upstream production.
EU ETSFuelEU MaritimeWTW2020 Baseline
EU LegislationRef: EU ETS Directive (amended) | EU Reg 2023/1805 (FuelEU Maritime)
Marine Engineer Notes
Onboard — EU ETS: The shipping company (typically the shipowner or bareboat charterer) is responsible for monitoring, reporting, and surrendering EUAs. The Chief Engineer's role is accurate fuel consumption recording — the same data feeds both IMO DCS/CII and EU MRV (Monitoring, Reporting, Verification). Errors in fuel logs have dual regulatory consequences.
Onboard — FuelEU: FuelEU evaluates the full Well-to-Wake GHG intensity of every fuel used. This means the fuel's production pathway matters — LNG from conventional sources has a different WTW value than bio-LNG. Bunker delivery notes and fuel certificates must capture fuel type with upstream GHG data.
MEO oral angle: Examiners increasingly ask about the EU instruments as well as IMO instruments. Key distinction: EU ETS is an economic (financial) mechanism; FuelEU is a technical (intensity) standard. Both apply simultaneously to EU-trading vessels.
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2023 GHG Strategy & Net-Zero Path · 2023–2024
July 2023
MEPC 80 — Revised 2023 IMO GHG Strategy
Net-zero by or around 2050 confirmed. Checkpoints: ≥20% total GHG reduction by 2030 (striving 30%), ≥70% by 2040 (striving 80%). ZNZ fuels ≥5% of energy by 2030.
MEPC 80 (July 2023) adopted the Revised IMO 2023 Strategy:
2030: ≥20% total GHG vs 2008, striving 30% 2040: ≥70% reduction, striving 80% 2050: Net-zero by or around (close to) 2050 ZNZ uptake: ≥5% of energy (striving 10%) from zero/near-zero GHG fuels by 2030
MEO oral angle: The 2023 Strategy replaced the 2018 Initial Strategy. Key upgrade: the 2018 strategy said ≥50% reduction by 2050; the 2023 strategy says net-zero by or around 2050 — a materially more ambitious target. Examiners may ask you to compare them. The 2023 strategy also introduced the ZNZ uptake target — something entirely absent from the 2018 version.
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2024
MEPC 81 & 82 — Mid-Term Measure Legal Text Development
Two instruments confirmed: GFI standard + carbon pricing. GFI reference locked at 93.3 gCO₂eq/MJ. Legal text drafted for MARPOL Annex VI amendment.
MEPC 81 (March 2024) and MEPC 82 (October 2024) confirmed: (1) GFI standard (technical), (2) carbon pricing mechanism (economic). Scope: all ships ≥5,000 GT (~85% of shipping CO₂). GFI reference: 93.3 gCO₂eq/MJ (2008 baseline, WTW). ISWG-GHG groups drafted MARPOL Annex VI Chapter 5 legal text.
World's first instrument combining mandatory emissions limits AND GHG pricing across an entire industry sector. Approved 63-16. GFI reference 93.3 gCO₂eq/MJ. ZNZ ≤19.0 gCO₂eq/MJ for 2028–2034.
A landmark session. MEPC 83 (April 2025) approved the draft legal text for the IMO Net-Zero Framework (NZF) — new Chapter 5 of MARPOL Annex VI — by a 63-16 majority vote:
GFI Standard: Phase 1 (2028–2034): Base ~89.6 gCO₂eq/MJ (−4% from 93.3) | ZNZ reward threshold: ≤19.0 gCO₂eq/MJ From 2035: Base tightens; ZNZ threshold drops to 14.0 gCO₂eq/MJ 2040: Base target = 65% reduction (~32.7 gCO₂eq/MJ)
Economic Mechanism: Ships below base threshold acquire Remedial Units (pay into IMO fund); ZNZ ships receive financial rewards.
MEPC 83NZFChapter 5GFI Standard63-16 Vote
IMO ResolutionRef: MEPC 83, April 2025 | MARPOL Annex VI Draft Chapter 5
Marine Engineer Notes
What 93.3 gCO₂eq/MJ means in practice: This is the WTW GHG intensity of the average 2008 marine fuel mix. HFO today sits at approximately 89–91 gCO₂eq/MJ (TTW basis) — above the base threshold even before WTW uplift from upstream production. No conventional fossil fuel will meet the ZNZ threshold of 19.0 gCO₂eq/MJ. Green ammonia and green hydrogen can, subject to certified upstream pathways.
MEO oral angle: The NZF is the mid-term measure called for by both the 2018 and 2023 strategies. It sits in MARPOL Annex VI Chapter 5 (separate from Chapter 4 which houses EEDI/EEXI/CII). Know the chapter structure.
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Pending IMO confirmation
October 2025
MEPC/ES.2 — Extraordinary Session: Adoption Not Concluded
Extraordinary session convened to formally adopt NZF amendments to MARPOL Annex VI. Concluded without adoption — text returned to working groups for refinement, not a simple procedural adjournment.
The Extraordinary Session of MEPC (MEPC/ES.2) was convened specifically to formally adopt the Net-Zero Framework as new Chapter 5 of MARPOL Annex VI. The session concluded without formal adoption — the text was returned to working groups for refinement due to unresolved disagreements, primarily around the design of the economic mechanism and Remedial Unit revenue redistribution.
Practical impact: Earliest possible entry into force shifts from March 2027 to potentially March 2028. The 1 January 2028 GFI monitoring start date remains the commercial deadline — but industry planning faces continued uncertainty.
Source note: This event is reported by DNV, LR, and ClassNK MEPC summary documents. Pending publication of an official IMO circular. Marked for verification.
MEPC/ES.2NZF DelayedText to WG
Class SocietyRef: DNV/LR/ClassNK MEPC/ES.2 Reports — IMO circular pending
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April 2026
MEPC 84 — NZF Guidelines, 5th GHG Study & NE Atlantic ECA
NZF implementation guidelines reviewed. 5th GHG Study ToR finalised — significant: will recalculate shipping's share, assess EEXI/CII effectiveness, and inform 2033–2035 NZF reviews. NE Atlantic ECA adopted.
MEPC 84 (April 2026) approved several items:
NZF Guidelines: Mid-term measure guidelines reviewed; revised work plan approved. OCCS: Revised work plan; Correspondence Group re-established to develop on-board carbon capture methodology. 5th IMO GHG Study: Terms of Reference finalised. Study commences 2026, to be completed by 2028. This study will: (1) recalculate shipping's current share of global emissions, (2) assess whether EEXI and CII have reduced carbon intensity as intended, (3) provide the emissions data needed to inform GFI tightening in the 2033/2035 NZF 5-year review, and (4) support the 2040 checkpoint assessment. NE Atlantic ECA: New Emission Control Area covering Greenland waters — extends SOx/NOx controls to Arctic trade routes. ISWG-GHG 22 & 23: Two intersessional sessions scheduled before MEPC 85 to progress NZF legal text.
MEPC 845th GHG StudyOCCSNE Atlantic ECA
Class SocietyRef: MEPC 84, April 2026 | ClassNK/LR/DNV MEPC 84 Reports
Marine Engineer Notes
Why the 5th GHG Study matters to you onboard: Its findings will directly determine how aggressively GFI thresholds tighten from 2035 onward. If the study shows EEXI/CII have delivered meaningful carbon intensity reductions, the 5-year NZF review may set more achievable 2035 targets. If they haven't, expect tighter thresholds.
OCCS relevance: On-board carbon capture systems — if the IMO methodology is approved — would allow a vessel to claim credit for CO₂ captured and stored. This could change CII calculations and GFI reporting. Watch for MEPC circulars on OCCS methodology post-MEPC 84.
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Future Checkpoints & Targets · 2027–2050
Forecast / Expected
2026 (Expected)
MEPC/ES.3 — Second Attempt at NZF Adoption
A second extraordinary MEPC session is expected to attempt formal NZF adoption. Not yet officially scheduled — conditional on ISWG-GHG 22 & 23 resolving outstanding text issues.
Following the October 2025 adjournment, a second extraordinary MEPC session (MEPC/ES.3) is expected in 2026. ISWG-GHG 22 and 23 (both scheduled before MEPC 85) will attempt to resolve the outstanding disagreements on the economic mechanism before any adoption session is convened.
This is a scenario-based outlook, not a confirmed IMO scheduled event. If adopted in 2026, entry into force via the tacit acceptance procedure would be 2027–2028. If not resolved, the 1 January 2028 GFI monitoring start date may be at risk.
Ships ≥5,000 GT begin collecting annual GFI data for compliance reporting.
Base threshold: ~89.6 gCO₂eq/MJ (−4% from 93.3 ref.) | ZNZ threshold: ≤19.0 gCO₂eq/MJ
No conventional fossil fuel qualifies for the ZNZ reward tier — including low-methane-slip LNG. Green hydrogen, green ammonia, advanced biofuels, and e-methanol can qualify subject to certified WTW pathways.
GFI Phase 12028 ComplianceZNZ 19.0Remedial Units
Ref: IMO NZF, MEPC 83 | Bureau Veritas NZF Analysis
Marine Engineer Notes
Commercial consequence for fleet operators: The Remedial Unit cost is effectively a carbon tax on conventional fuel use above the base threshold. Fleet operators will model this cost against the capital cost of alternative fuel conversions. The Chief Engineer's fuel consumption data directly informs that commercial decision.
MEO oral angle: When asked about alternative fuels for GFI compliance, structure your answer: (1) WTW accounting basis — upstream production matters; (2) ZNZ threshold is 19.0 gCO₂eq/MJ 2028–2034, drops to 14.0 from 2035; (3) no fossil fuel qualifies; (4) green NH₃ and green H₂ are the primary candidates.
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2030
2030 Indicative Checkpoint
Total GHG: −20% vs 2008 (striving −30%). Carbon intensity: −40%. ZNZ fuels ≥5% of energy (striving 10%). Not a hard legal limit — an indicative milestone under the 2023 GHG Strategy.
2023 IMO GHG Strategy checkpoint: ≥20% total GHG vs 2008 (striving 30%) | Carbon intensity ≥40% improvement | ZNZ fuels ≥5% of energy (striving 10%).
This is not a hard legal limit with individual ship sanctions. It is a fleet-level strategic checkpoint. CII annual reduction factors continue tightening under MARPOL Annex VI through this period.
2030 Checkpoint-20% GHGZNZ 5%
Ref: 2023 IMO GHG Strategy | MEPC 80
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2035
GFI Phase 2 — ZNZ Threshold Tightens
ZNZ threshold drops from 19.0 → 14.0 gCO₂eq/MJ. Base tier tightens further. 5-year NZF review (~2033) may adjust based on fuel availability and technology maturity.
From 2035, GFI thresholds tighten significantly: ZNZ drops from 19.0 → 14.0 gCO₂eq/MJ. Practical compliance will require green hydrogen, green ammonia, e-methanol, or advanced biofuels. The first 5-year NZF review (~2033) may revise these thresholds.
GFI Phase 2ZNZ 14.0H₂ / NH₃
Ref: IMO NZF, MEPC 83
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2040
2040 Indicative Checkpoint
Total GHG: −70% vs 2008 (striving −80%). GFI base target: −65% from reference (~32.7 gCO₂eq/MJ). Near-complete elimination of conventional marine fuels required at fleet scale.
2023 IMO GHG Strategy: ≥70% total GHG reduction vs 2008, striving 80%. GFI base target for 2040: 65% reduction from 93.3 gCO₂eq/MJ reference (~32.7 gCO₂eq/MJ). Near-complete elimination of HFO and conventional marine fuels from the global fleet required.
2040 Checkpoint-70% GHGGFI 65%
Ref: 2023 IMO GHG Strategy | IMO NZF | MEPC 80/83
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By/Around 2050
IMO Net-Zero GHG Goal
Net-zero GHG from international shipping — well-to-wake basis. "Close to 2050" allows for fuel transition realities. OCCS may close the final gap. NZF reviewed every 5 years.
Net-zero GHG emissions from international shipping by or around (close to) 2050 — well-to-wake accounting. All fleet segments covered. On-board Carbon Capture and Storage (OCCS) may close the final gap — methodology under development. NZF reviewed every 5 years to adjust targets based on fuel availability and market conditions.
MEO oral perspective: "Net-zero by or around 2050" is deliberately qualified — the phrase "close to" was inserted to acknowledge that full net-zero may not be technically achievable for all ship types by exactly 2050. Carbon capture (OCCS) is being developed precisely for this residual gap.
Career context: Engineers sitting MEO Class 1 orals today will be Senior Superintendents and Fleet Technical Managers when the 2040 checkpoint is assessed. The regulatory sequence — EEDI → DCS → CII → EEXI → NZF → Net-Zero — is the entire arc of your professional career in the industry.
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About this timeline: Compiled by Marine Intelligence Weekly from IMO meeting summaries, MARPOL Annex VI texts, and class society MEPC reports. EU Instruments (EU ETS, FuelEU) are parallel regional measures — not IMO instruments. Future Checkpoints are indicative targets from the 2023 IMO GHG Strategy and NZF, not yet legally binding milestones unless adopted as MARPOL amendments. Events marked "Pending IMO confirmation" are sourced from secondary class society summaries; primary IMO circulars are pending. Events marked "Forecast / Expected" are scenario-based outlooks, not officially scheduled sessions. Corrections: contactus@marineintelligenceweekly.com
Source classification:IMO Resolution Official IMO meeting outcome or adopted instrument
MARPOL Reg. MARPOL Annex VI regulation text
Class Society DNV / LR / ClassNK / BV analysis
EU Legislation EU regulation or directive text