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:
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.
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.