MEPC 83 — IMO Net-Zero Framework + GHG Fuel Standard

MEPC 83 (7-11 April 2025) adopted the IMO Net-Zero Framework — the largest single regulatory adoption in IMO history in terms of forward economic + operational impact. The Framework consists of two interlocking instruments: (a) the GHG Fuel Standard (GFS) setting a mandatory declining well-to-wake (WtW) GHG intensity trajectory for marine fuels, and (b) the IMO Net-Zero Fund establishing a marine carbon-pricing mechanism with remedial-unit (RU) trading. Together they operationalise the 2023 IMO Strategy targets (MEPC.377(80)) — 20% GHG reduction by 2030, 70% by 2040, net-zero by or around 2050. The Framework enters into force 2027 with first compliance year 2028. Every merchant vessel Master + DPA + fleet Chief Engineer needs to understand the mechanics.

The two-part Framework

GHG Fuel Standard (GFS)

Every ship >5,000 GT engaged in international voyages must not exceed a declining WtW GHG intensity limit measured in gCO2eq/MJ. The base year is 2008 (baseline ~93.3 gCO2eq/MJ per IMO calculation). Two-tier reduction trajectory:

Base Target (mandatory). Progressive reduction — 4% below baseline by 2028, ~30% by 2035, ~65% by 2040, ~89% by 2050.
Direct Compliance Target (stricter, elective). Approximately additional 10-15 pp below Base at each year. Ships meeting Direct earn Surplus Units for trade.

IMO Net-Zero Fund + Remedial Units

Non-compliant ships must acquire Remedial Units (RUs) to close the gap between actual emissions + the compliance target. Two price tiers proposed at MEPC 83:

Tier 1 RU price: ~$100/tCO2eq for shortfall below Direct Compliance Target but above Base Target.
Tier 2 RU price: ~$380/tCO2eq for shortfall below Base Target (much more penal).

Fund proceeds finance: (a) Just Transition programmes for developing-country seafarer + shipyard workers, (b) R&D for zero-carbon fuel production + bunker infrastructure, (c) Small Island Developing States (SIDS) + Least Developed Countries (LDC) climate adaptation.

Well-to-wake (WtW) GHG intensity — the measurement basis

GFS uses full well-to-wake life-cycle emissions accounting — a major shift from the tank-to-wake (TtW) basis used for CII and EEXI. WtW captures upstream extraction + processing + transport emissions in addition to combustion. Practical implication: fossil fuels get roughly the same score under WtW as TtW (~90-95 gCO2eq/MJ). But alternative fuels see substantial differentiation:

e-methanol (green H2 + captured CO2). ~5-15 gCO2eq/MJ WtW — deep decarbonisation.
Bio-methanol (waste feedstock). ~10-30 gCO2eq/MJ WtW.
Blue ammonia (H2 from natural gas + CCS). ~40-60 gCO2eq/MJ WtW.
LNG (fossil). ~76-95 gCO2eq/MJ WtW depending on methane slip — the IMO 2020 sulphur cap fuel of choice becomes problematic post-2030 unless methane slip mitigated.
VLSFO / MGO / HFO (fossil). ~90-95 gCO2eq/MJ WtW baseline.

Timeline + entry into force

Year	Milestone	Status
2023 (MEPC 80)	2023 IMO Strategy (MEPC.377(80)) — targets 20/70/net-zero	Adopted
April 2025 (MEPC 83)	IMO Net-Zero Framework (GFS + Fund) adopted as MARPOL Annex VI amendments	Adopted (subject to tacit acceptance)
March 2027	Framework enters into force (16 months tacit acceptance)	Planned
Jan 2028	First GFS compliance year begins	Planned
2030	Interim milestone — 20% total sector GHG reduction target	Target
2035	GFS trajectory 30% reduction; MEPC review of Framework	Scheduled review
2040	70% total sector GHG reduction target	Target
2050	Net-zero (or around)	Aspiration

Interaction with existing regulations

EU ETS (in force 2024). Existing EU emission trading scheme continues in parallel. Vessels calling EU ports still owe EU allowances on their Europe-portion emissions. Regional-vs-global regulatory overlap is a known operational cost.
EU FuelEU Maritime (in force 2025). The EU's own WtW GHG intensity standard for vessels calling EU ports — trajectory is broadly aligned but stricter than IMO GFS Base Target. Ships operating primarily on EU trades will find FuelEU the binding constraint.
CII rating (in force 2023). CII continues alongside; performance rating (A-E) is unchanged. See /reference/cii-rating.
EEXI (in force 2023). Continues — technical design constraint on existing ships.

Practical implications for shipowners + officers

Fuel accounting. Every bunker delivery note must carry certified WtW GHG intensity documentation. Fuel supplier certification is expected to be regulated separately by 2027.
Voyage-level reporting. Each vessel reports annual GHG intensity + fuel consumption + Surplus/Remedial Unit balance. Extends existing MRV + SEEMP framework.
Newbuild fuel choice. Ordering a fossil-fuel-only ship in 2026 with 25-year design life is now a commercial + regulatory risk — the ship will face escalating Tier 2 RU costs from 2028 onward and progressive economic obsolescence.
Ammonia + methanol dual-fuel becoming standard. Yard order books for 2027-2030 delivery are dominated by dual-fuel ammonia-ready + methanol-capable designs. See /reference/methanol-ammonia-dual-fuel.
Officer training. STCW-level training in ammonia + methanol handling becoming standard requirement. IMO Model Course updates in progress.