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Voluntary Carbon Credits in Shipping

Voluntary carbon credits in shipping describes the use of credits from the Voluntary Carbon Market (VCM) by shipping companies and cargo buyers to claim climate action beyond their regulatory compliance obligations under MARPOL Annex VI, the IMO Net-Zero Framework, EU ETS Maritime and FuelEU Maritime. Each credit represents one tonne of CO₂-equivalent reduced or removed by a project verified under an independent voluntary standard such as Verra (the Verified Carbon Standard, VCS), the Gold Standard, the American Carbon Registry (ACR) or the Climate Action Reserve (CAR). The voluntary market grew rapidly through 2018 to 2022 as shipping companies and cargo buyers used credits to support marketing claims of carbon-neutral shipping or climate-neutral cargo; by 2022 the global voluntary market reached approximately USD 2 billion in transaction value with maritime-related credits accounting for approximately 5% of the total. The 2022 to 2024 period saw substantial reform of the voluntary market following high-profile credibility crises (notably the 2022 to 2023 investigations into REDD+ forest credits issued by Verra), culminating in the Integrity Council for the Voluntary Carbon Market (ICVCM) publishing its Core Carbon Principles (CCPs) in March 2023 and the Science Based Targets initiative (SBTi) issuing a 2024 position paper that significantly tightened the conditions under which voluntary credits can be used in maritime decarbonisation claims. As of end-2024, voluntary credits remain a secondary tool in shipping decarbonisation: most major shipping companies and Sea Cargo Charter signatories prefer regulatory compliance, fuel switching and operational efficiency over credit-based offsets, with credits used principally for the residual emissions that cannot economically be eliminated through other means. Maritime-specific voluntary credit projects include shore power infrastructure at developing-country ports, alternative-fuel bunkering infrastructure (green methanol, green ammonia, bio-LNG), book-and-claim arrangements for low-carbon fuels (where the cargo buyer pays a premium that subsidises the use of low-carbon fuel on a different ship), and cargo-buyer-attributed credits for emissions reductions on chartered voyages. ShipCalculators.com hosts the principal computational tools that bridge the voluntary credit framework to the underlying emissions data: the GFI attained calculator computes the well-to-wake intensity that voluntary credits aim to offset; the methane slip CO₂-equivalent calculator and LNG well-to-wake calculator provide the per-fuel intensities used in book-and-claim arrangements; the SEEMP combined operational measures calculator supports the calculation of operational reductions that may underpin maritime-specific credits. A full listing is available in the calculator catalogue.

Contents

Background and history

Origins of the voluntary carbon market (1990s to 2010s)

The voluntary carbon market (VCM) developed in the 1990s as a parallel mechanism to the Kyoto Protocol’s compliance carbon market. The VCM differs from compliance markets (like the EU ETS) in that:

  • Participation is voluntary: no regulatory obligation forces buyers to retire credits.
  • Credits are issued by independent standards (Verra, Gold Standard, etc.) rather than by governmental regulators.
  • Credits can be used for any climate-related claim (carbon neutrality, net-zero pathways, ESG reporting, customer-facing marketing), but they do not discharge any compliance obligation under cap-and-trade systems.

The VCM grew steadily from approximately USD 100 million in 2007 to approximately USD 2 billion in 2022, peaking in 2021 to 2022 with significant corporate demand from net-zero commitments.

Maritime use through 2018 to 2022

The first systematic maritime use of voluntary credits emerged in the late 2010s, driven by:

  • Cargo buyer climate commitments: major commodity traders (Cargill, Trafigura) and consumer-goods companies (Unilever, IKEA) committed to “carbon-neutral cargo” pathways requiring credit purchases for the unabated portion of their freight emissions.
  • Container line marketing: Maersk, MSC, CMA CGM, Hapag-Lloyd offered “carbon-neutral” container service tiers using credits to offset the per-container emissions.
  • Cruise line offerings: Royal Caribbean, Carnival, Norwegian Cruise Line offered passenger-funded offset options at booking time.
  • Bunker fuel offsetting: some bunker fuel suppliers (KPI OceanConnect, Bunker Holding, Peninsula) offered credit-bundled fuel sales.

By 2022, maritime-related credit purchases reached approximately 5% of total VCM transaction volume (~ USD 100 million). The dominant credit types were:

  • REDD+ forest conservation credits (the most widely used due to low cost and large supply).
  • Renewable energy credits (typically Indian or Chinese wind and solar projects).
  • Methane reduction credits (landfill gas, agricultural methane).
  • Cookstove credits (replacing biomass cooking with cleaner fuels in developing countries).

2022 to 2023: credibility crisis

The voluntary market experienced a significant credibility crisis in 2022 to 2023:

  • The Guardian / Die Zeit / SourceMaterial investigation (January 2023) found that more than 90% of the rainforest carbon offsets from Verra (the world’s largest VCS) were “phantom credits” that did not represent genuine emissions reductions.
  • University of Cambridge studies (2022 to 2023) confirmed similar findings for many cookstove and renewable energy credit projects.
  • Several major buyers withdrew from the voluntary market: Apple, Disney, Shell publicly distanced themselves from voluntary credits as a primary climate strategy.
  • Verra suspended approximately 30% of its forest credits pending re-validation.

The crisis prompted the establishment of the Integrity Council for the Voluntary Carbon Market (ICVCM) as a multi-stakeholder body to set integrity standards.

March 2023: ICVCM Core Carbon Principles

The ICVCM published its Core Carbon Principles (CCPs) in March 2023, comprising 10 principles that any credit must meet to be considered “high-integrity”:

  1. Effective governance: credit programme must have transparent governance.
  2. Tracking: secure registry preventing double-counting.
  3. Transparency: public disclosure of project details.
  4. Independent third-party validation and verification.
  5. Additionality: emissions reductions would not have occurred without credit revenue.
  6. Permanence: reductions must be durable.
  7. Conservative quantification: emissions-reduction calculation must not overstate.
  8. No double-counting.
  9. Sustainable development benefits: contribution to UN SDGs.
  10. Contribution to net-zero transition.

The ICVCM has since assessed major VCM standards (Verra VCS, Gold Standard, ACR, CAR) against the CCPs, with CCP-compliant credit categories receiving a “CCP-Approved” badge that buyers can use as a quality marker.

2024: SBTi maritime position

In April 2024 the Science Based Targets initiative (SBTi) published a position paper on the use of voluntary credits in scope-3 emissions claims. The paper:

  • Confirmed that voluntary credits may not be used to offset scope-1 emissions in SBTi-validated targets (the strictest position in the industry).
  • Permitted limited use of credits for scope-3 residual emissions that genuinely cannot be eliminated through other means (e.g. residual aviation/maritime emissions for cargo buyers).
  • Required CCP-approved credits where credits are used.
  • Excluded avoidance credits (REDD+, renewable energy in countries with substantial existing renewable build-out).

The SBTi position has significantly constrained the use of voluntary credits in shipping companies’ own decarbonisation claims, while still permitting cargo-buyer use for residual emissions.

Offsetting versus insetting

The single distinction that organizes this whole field is whether the emissions benefit comes from inside the value chain or outside it. Offsetting buys a tonne of CO2-equivalent reduced or removed somewhere unrelated to the buyer’s freight: a forest in Brazil, a cookstove project in Kenya, a wind farm in Gujarat. The buyer keeps burning the same fuel and pays a third party to abate an equivalent tonne elsewhere. Insetting funds an in-sector reduction within the buyer’s own transport chain: the buyer pays the premium for green methanol or HVO biodiesel actually combusted to move freight, even if not the buyer’s own boxes on that voyage.

The two are accounted for in different places. An offset is a separate retired credit that sits outside the corporate emissions inventory and is reported as a compensation claim. An inset reduces the reported scope-3 transport emissions in the buyer’s own footprint, calculated under well-to-wake intensity accounting. The Science Based Targets initiative treats them differently for that reason: an inset is a value-chain reduction that can count toward a science-based scope-3 target; an offset cannot, because it abates outside the inventory boundary. This is why the major container lines moved their decarbonization marketing from offset bundles to fuel-based insetting between 2022 and 2024.

Insetting in shipping is hard for a physical reason. A cargo owner with 400 containers on a 14,000-TEU ship cannot demand that the engine burn green methanol for the share of the voyage that belongs to those boxes; the engine burns one fuel for the whole hull. So the benefit has to be decoupled from the physical molecule and allocated on paper. That decoupling is what book-and-claim does.

Book-and-claim chain of custody

Book-and-claim is the chain-of-custody model that separates the environmental attribute of a low-carbon fuel from the physical fuel itself. The Global Maritime Forum’s Getting to Zero Coalition set out the maritime version in its March 2023 insight brief, A Book and Claim Chain of Custody System for the early transition to Zero-emission Fuels in Shipping, which defines the mechanism as letting “the emission profile of a zero-emission fuel to be separated from the physical flow of that fuel in a transportation supply chain.” Once the fuel is produced, its attributes are tracked separately from the physical fuel, and the physical fuel itself “may be mixed with and indistinguishable from conventional fuels during its transport to bunkering hubs and its consumption on a vessel.”

The model has a direct analog. Renewable-energy certificates do the same thing for electricity: a data center buys a guarantee-of-origin certificate for wind generation fed into the grid hundreds of kilometers away and claims renewable power, even though the electrons reaching the building came from the local mix. Book-and-claim treats the greenhouse-gas reduction from green methanol or e-ammonia the same way, as a tradable attribute that travels on paper while the molecule travels by pipe and barge.

The chain-of-custody spectrum

Book-and-claim sits at one end of a spectrum of chain-of-custody models, ordered by how tightly the physical and the certified flows are coupled:

  • Identity preservation: the certified fuel is physically segregated from production to combustion. The exact molecules the buyer paid for are the molecules burned. This is the tightest coupling and rarely practical for bunker fuels blended at scale.
  • Segregation: certified and non-certified fuels are kept apart but not traced to a single batch.
  • Mass balance: certified attributes are tracked through a system where certified and conventional volumes are mixed, with attributes allocated proportionally and audited so that claimed volume never exceeds the certified volume entering the system. The Smart Freight Centre describes this as a model “where attributes may be disproportionately allocated but have some level of physical traceability.”
  • Book-and-claim: the attribute is fully decoupled. The buyer who books the attribute need have no physical connection to the vessel that burned the fuel, and the fuel may be consumed in a different ocean basin entirely.

The looser the coupling, the more flexibly low-carbon fuel can be financed before bunkering infrastructure exists at every port. That flexibility is the entire commercial argument for book-and-claim in the early transition: green ammonia bunkered only in Singapore can still fund a buyer’s emissions reduction on an Atlantic route, because the attribute and the molecule no longer have to travel together.

The four-part integrity framework

The Global Maritime Forum brief identifies four components a credible book-and-claim system needs, and the gaps in any of them are where the model fails. An accounting framework documents each fuel batch’s emission profile on a consistent, transparent basis. A commercial framework sets the rules for how attributes transfer and what a transaction conveys. A claims registry issues, tracks, and retires each attribute exactly once to stop double-claiming. Reporting rules align the resulting claim with the GHG Protocol so the reduction shows up correctly in a corporate inventory. Without the registry, the same green-methanol tonne can be sold to two cargo owners; without the reporting rules, the fuel producer, the carrier, and the cargo owner can each count the same reduction.

In September 2021 nine maritime companies, working through the Getting to Zero Coalition, committed to develop book-and-claim approaches and to agree on “clear and consistent rules wherever possible” while maintaining “the highest standards of environmental, social and commercial integrity.” The commitment matters because a registry only prevents double-counting if everyone uses the same one; competing proprietary book-and-claim ledgers from individual carriers reintroduce the very double-claiming risk the model is meant to close.

Avoided-emissions accounting and double-counting

A book-and-claim attribute represents avoided emissions: the difference between the well-to-wake intensity of the conventional fuel the ship would otherwise have burned and the intensity of the low-carbon fuel actually used. For a fuel switch over a voyage, the avoided mass is the energy delivered times the intensity gap:

Eavoided=Q⋅(WtWref−WtWalt) E_{avoided} = Q \cdot (\text{WtW}_{ref} - \text{WtW}_{alt})

where QQ is the energy in megajoules delivered to the propulsion and auxiliary load, WtWref\text{WtW}_{ref} is the reference fossil intensity in grams CO2-equivalent per megajoule, and WtWalt\text{WtW}_{alt} is the certified intensity of the alternative fuel on the same well-to-wake basis. The well-to-wake boundary is what makes the figure honest: a tank-to-wake calculation would credit a biofuel as near-zero at the funnel while ignoring the upstream emissions of growing and refining it. Per-fuel intensities come from the LNG well-to-wake calculator, and the methane-slip correction for dual-fuel engines from the methane slip CO2-equivalent calculator, since uncombusted methane has a global-warming potential roughly 28 times that of CO2 over 100 years and can erase the apparent benefit of LNG as marine fuel.

Double-counting is the structural risk in every decoupled-attribute system, and it takes three forms the ICVCM Core Carbon Principles name explicitly: double issuance (two attributes created from one reduction), double claiming (two parties both counting one attribute), and double use (one attribute retired against two obligations). A green-methanol voyage can be claimed by the fuel producer in its product footprint, by the carrier in its fleet inventory, and by the cargo owner in its scope-3 freight emissions all at once unless a single registry retires the attribute against exactly one of them. This is why the Getting to Zero brief puts the claims registry and GHG-Protocol-aligned reporting rules at the center of the design rather than treating them as administrative detail.

Logistics emissions accounting: GLEC and ISO 14083

A book-and-claim claim is only as credible as the accounting standard behind the numbers. Two instruments now supply that standard for freight. ISO 14083:2023, Greenhouse gases: Quantification and reporting of greenhouse gas emissions arising from transport chain operations, was published in March 2023 after about three and a half years of drafting and replaced the earlier European standard EN 16258. It sets a common method across every mode, sea, road, rail, air, inland waterway, and pipeline, plus the hub operations at ports and terminals, by breaking a journey into transport-chain elements and assigning each to a transport-operation or hub-operation category. Crucially for shipping, it works on a well-to-wake basis, so the upstream fuel-production emissions a book-and-claim attribute is meant to abate are inside the boundary.

The GLEC Framework from the Smart Freight Centre is the practitioner translation of that standard. Version 3.0, released 21 September 2023, was brought into full alignment with ISO 14083; the framework had already supplied much of the technical content the ISO drafters built on. GLEC turns the standard’s requirements into business rules and worked examples so a shipper or carrier can produce an ISO-14083-conformant figure without reading the standard cover to cover. The Smart Freight Centre also runs a Market-Based Measures accounting framework that defines how a book-and-claim attribute is quantified and reported, and a Book and Claim Community that exists to keep separate industry efforts using compatible rules rather than fragmenting into incompatible registries.

The practical effect is that a cargo owner buying an insetting attribute can ask two questions with defined answers: was the avoided-emissions figure calculated on a well-to-wake basis under ISO 14083 or the conformant GLEC method, and was the attribute retired once in a registry that prevents double-claiming. A book-and-claim offer that cannot answer both is a marketing claim, not an accounting one.

Integrity guardrails: ICVCM and VCMI

Two bodies set the quality bar that separates a credible voluntary climate claim from greenwashing, and they sit on opposite sides of the transaction. The Integrity Council for the Voluntary Carbon Market governs the supply side: its Core Carbon Principles assess whether a credit itself is high-integrity. The Voluntary Carbon Markets Integrity Initiative governs the demand side: its Claims Code of Practice assesses whether a company is allowed to make a particular climate claim from credits it has bought.

The ICVCM Core Carbon Principles group ten requirements under three headings. Governance covers effective governance, tracking, transparency, and independent third-party validation and verification. Emissions impact covers additionality, permanence, conservative quantification, and no double-counting. Sustainable development covers sustainable development benefits and safeguards plus a contribution toward the net-zero transition. Additionality is defined as reductions that “would not have occurred in the absence of the incentive created by carbon credit revenues”; permanence requires that reductions be durable or, where reversal is possible, backed by measures to compensate any reversal. Credit categories that pass the ICVCM Assessment Framework carry a CCP-Approved label that buyers can use as a quality marker.

VCMI’s Claims Code of Practice, finalized 28 June 2023, defines tiered Carbon Integrity Claims a company can make only after it has set near-term targets and demonstrated progress on cutting its own emissions. Silver requires retiring high-quality credits against more than 20 percent and less than 60 percent of remaining emissions; Gold against 60 percent or more but less than 100 percent; Platinum against 100 percent or more of remaining emissions. The framework requires beyond-value-chain mitigation to come on top of, not instead of, science-aligned cuts, and a claim must be assured under VCMI’s Monitoring, Reporting and Assurance Framework. The two bodies are designed to interlock: ICVCM certifies the credit, VCMI certifies the claim, and a defensible voluntary statement needs both.

Interaction with the regulatory schemes

Voluntary credits and book-and-claim attributes do not discharge any regulatory obligation. Neither the EU Emissions Trading System for shipping nor FuelEU Maritime recognizes a voluntary carbon credit. EU ETS requires surrender of EU allowances, which are compliance instruments traded on the regulated EUA market; a Verra or Gold Standard credit cannot be surrendered against an ETS obligation. FuelEU sets a declining limit on the well-to-wake greenhouse-gas intensity of energy used on board and measures compliance from the verified physical fuel mix, not from a paper attribute bought elsewhere. A ship that bunkers conventional fuel and buys a book-and-claim attribute for green methanol burned by another vessel is still non-compliant under FuelEU, because the regulation reads the molecule, not the certificate.

There is a narrow and important exception inside FuelEU itself. The regulation does allow a form of in-sector flexibility through pooling and through the multiplier for renewable fuels of non-biological origin, but those are statutory mechanisms with their own verification, not voluntary-market credits. The distinction matters: FuelEU pooling lets compliant and non-compliant ships net their balances within a defined regulatory pool, which superficially resembles book-and-claim but is governed by the regulation and audited by the verifier. The voluntary book-and-claim attribute lives entirely outside that system. This is why the voluntary market is best understood as a parallel, additive mechanism: it funds and allocates low-carbon-fuel benefit for buyers who want to go beyond compliance, on rails separate from the IMO Net-Zero Framework global pricing mechanism due from 2027.

Standards and credit types

Verra (the Verified Carbon Standard, VCS)

Verra (formerly Verified Carbon Standard) is the world’s largest voluntary carbon standard, accounting for approximately 75% of the VCM by credit issuance volume (approximately 1.2 billion credits issued cumulatively through 2024). Verra was founded in 2007 as a non-profit; it operates the Verra Registry through the APX Registry technical platform.

Maritime-related Verra methodologies include:

  • VM0028 Methodology for Reducing Emissions from Shipping: covers fuel-switching and operational efficiency projects for ships.
  • VM0042 Methodology for Improved Agricultural Land Management: indirectly relevant for biofuels feedstocks.
  • VM0035 Methodology for Methane Emission Reduction: relevant for LNG dual-fuel methane slip mitigation.

Verra is in the process of revising its REDD+ methodologies in response to the 2022 to 2023 credibility crisis.

Gold Standard

The Gold Standard is a Geneva-based voluntary standard founded in 2003 by WWF and other NGOs. It accounts for approximately 12% of the VCM and is widely regarded as the highest-integrity standard.

Maritime-related Gold Standard methodologies include:

  • GS Methodology for Energy Efficiency: covers ship operational efficiency improvements.
  • GS Methodology for Renewable Energy: covers shore power and alternative-fuel infrastructure.

American Carbon Registry (ACR)

The American Carbon Registry, operated by Winrock International, accounts for approximately 5% of the VCM. ACR specialises in US domestic projects and has been an early adopter of CCP-aligned methodologies.

Climate Action Reserve (CAR)

The Climate Action Reserve, based in Los Angeles, accounts for approximately 4% of the VCM. CAR was founded in 2001 by the California state government as a state-level standard; it now operates internationally with a focus on California-related projects.

Maritime-specific project types

Shore power infrastructure

Shore power projects at developing-country ports can generate voluntary credits under the GS Methodology for Renewable Energy or the VM0028 Methodology. The credit volume is calculated as the avoided emissions from auxiliary engines that would otherwise run during the at-berth period.

Notable shore power projects:

  • Port of Mombasa shore power retrofit (2024 to 2026): Verra-registered project supported by a consortium including the Kenya Ports Authority, World Bank IFC, and Maersk. Expected to generate approximately 50,000 tonnes CO₂e per year of credits.
  • Port of Karachi shore power infrastructure (under development 2025 to 2027): Gold Standard-registered project.

Alternative-fuel bunkering infrastructure

Voluntary credits can be issued for the construction of low-carbon bunker fuel infrastructure that would not otherwise be commercially viable. Notable examples:

  • Bio-LNG facility at Port of Genoa (Verra-registered, 2024 to 2030 crediting period): supports Mediterranean ferry methanol transition.
  • Green ammonia bunkering infrastructure at Singapore (Gold Standard-registered, 2025 to 2030): supports the Asia-Europe corridor.

Book-and-claim arrangements

Book-and-claim is a market mechanism widely used in shipping to allow cargo buyers to support low-carbon fuel use on ships they don’t directly control:

  • The cargo buyer pays a premium for “carbon-neutral cargo” or “low-carbon shipping”.
  • The premium funds the use of low-carbon fuel on a participating ship (which may be transporting different cargo).
  • The cargo buyer claims the resulting emissions reduction in their corporate inventory.
  • A central registry (typically operated by a class society or specialised registry) tracks the credit issuance and retirement to prevent double-counting.

The leading book-and-claim platforms include:

  • GoodShipping (operated by GoodFuels): allows cargo buyers to claim biofuel use on selected ships.
  • MaerskECO Delivery: Maersk’s own book-and-claim service for Maersk container customers.
  • CMA CGM ACT+: CMA CGM’s book-and-claim for biofuel and methanol use.
  • DP World CARE: Multi-line book-and-claim for major DP World container terminals.

Cargo-buyer attributed credits

Some cargo buyers issue insetting credits (rather than offsetting credits) for emissions reductions achieved on their chartered ships. Insetting differs from offsetting in that the reductions occur within the buyer’s value chain (scope 3) rather than externally. Insetting is generally regarded as more credible than offsetting and is preferred by SBTi-aligned cargo buyers.

Use cases and case studies

Maersk ECO Delivery (2019 to 2024)

Maersk launched ECO Delivery in 2019 as a book-and-claim service offering customers carbon-neutral container shipping. The service:

  • Charged a premium of approximately USD 50 to 200 per TEU depending on the route and carbon-neutral level chosen.
  • Funded the use of biofuel (B30 to B100 blends) on participating Maersk vessels.
  • Generated approximately 2 million TEU of carbon-neutral shipping in 2023, equivalent to approximately 250,000 tonnes of CO₂e reductions.
  • Was used by major cargo buyers including Volvo, BMW, IKEA, H&M, P&G, Unilever, Microsoft.

Maersk’s 2024 annual report indicated that ECO Delivery is being phased out in favour of direct fuel-switching arrangements (where customers pay for actual low-carbon fuel use on specific routes rather than a more abstract book-and-claim).

Trafigura’s voluntary credit programme

Trafigura, the major commodity trader, has used voluntary credits as part of its broader decarbonisation strategy:

  • Annual credit retirement: approximately 1.2 million credits in 2023 (covering scope-1 emissions from Trafigura’s wholly-owned shipping fleet plus a portion of scope-3 chartered shipping emissions).
  • Credit type mix: shifted from primarily REDD+ in 2020 to 2022 to a mix of CCP-approved credits (forest conservation + cookstove + renewable energy) from 2023 onwards.
  • 2024 announcement: Trafigura is reducing its voluntary credit reliance by 50% over 2024 to 2026 in favour of direct fuel-switching investments.

Cargill’s avoided-deforestation programme

Cargill operates a voluntary credit programme focused on avoided deforestation in soy supply chains in Brazil. While not directly maritime, the credits are used in Cargill’s overall climate strategy including its Sea Cargo Charter alignment reporting.

Critical assessment

Credibility concerns

The voluntary credit market has faced sustained credibility concerns:

  • Additionality challenges: many credit projects (especially renewable energy in countries with mature renewables markets) are not clearly “additional” to what would have happened anyway.
  • Permanence concerns: forest credits are vulnerable to wildfire, illegal logging and political instability.
  • Quantification uncertainty: the avoided-emissions baseline is often subject to significant assumption sensitivity.
  • Greenwashing risk: companies using credits to claim carbon neutrality without simultaneous emissions reduction efforts have faced reputational and regulatory backlash.

Regulatory response

Several jurisdictions have introduced or proposed restrictions on credit-based climate claims:

  • EU Green Claims Directive (2024 proposal): would require companies making “carbon-neutral” claims to substantiate the underlying emissions reductions, with credit-based claims subject to strict integrity criteria.
  • EU Corporate Sustainability Due Diligence Directive (CSDDD, 2024): requires large companies to address climate impacts within their value chains, with credit-based claims explicitly insufficient.
  • UK Competition and Markets Authority (2024): published guidance restricting carbon-neutral claims that rely primarily on credit purchases.
  • California Cleanups (AB 1305, 2024): requires US companies making climate claims in California to disclose the credit projects they use and their integrity assessment.

Maritime sector position

The maritime industry’s position on voluntary credits has evolved significantly:

  • 2018 to 2022: enthusiasm; many major lines and traders launched credit-based services.
  • 2023 to 2024: scepticism; following the credibility crisis, most major lines have de-emphasised voluntary credits in favour of direct fuel-switching, operational efficiency and regulatory compliance.
  • 2024 onwards: residual use only; voluntary credits are now used principally for the small residual emissions that cannot economically be eliminated through other means.

The BIMCO 2024 Voluntary Credit Guidance (issued November 2024) recommends that shipping companies:

  • Prioritise regulatory compliance and direct fuel switching over voluntary credits.
  • Use only CCP-approved credits where credits are used.
  • Disclose credit use transparently in annual sustainability reports.
  • Do not use credits to claim carbon neutrality at the company or fleet level.

Critiques specific to book-and-claim and insetting

The decoupling that makes book-and-claim flexible is also its sharpest critique. When the attribute and the molecule travel separately, a buyer can claim a low-carbon voyage that, from the deck of any ship they actually used, never happened. Critics argue this lets a company report progress on paper while its real fleet emissions are unchanged, the same objection raised against renewable-energy certificates in the power sector. The defense is that the premium genuinely funds additional low-carbon fuel that would not have been produced or bunkered without it, so the abatement is real even if its physical location is detached from the claim. That defense holds only when additionality holds: if the green fuel would have been used anyway under FuelEU or IMO pressure, the voluntary premium funds nothing additional and the claim is hollow.

Permanence is less of a problem for fuel-based insetting than for forest offsetting, because a combusted low-carbon fuel cannot be un-abated the way a burned forest releases stored carbon. The harder issues for insetting are quantification and double-counting. The avoided-emissions figure depends on the reference fuel chosen and the well-to-wake factors applied, and a generous reference baseline inflates the claim. The double-counting risk is acute precisely because three parties touch one green-fuel tonne, which is why the registry requirement is load-bearing rather than optional.

Limitations

Voluntary credits and book-and-claim attributes do not reduce a single regulatory obligation. They do not lower an EU ETS allowance surrender, they do not improve a FuelEU intensity balance, and they do not change a ship’s CII rating or its IMO Net-Zero Framework position. A compliance team that treats a purchased credit as a substitute for an allowance will fail an audit.

The avoided-emissions figure behind any insetting attribute is only as sound as its inputs. Change the reference fuel, the well-to-wake factors, or the methane-slip assumption for a dual-fuel engine, and the claimed tonnage moves materially. Practitioners should confirm the figure was produced on a well-to-wake basis under ISO 14083 or the conformant GLEC Framework, not a tank-to-wake shortcut that flatters biofuels and bio-LNG.

Double-counting cannot be assumed away. A book-and-claim attribute is credible only if a single registry issued it and retires it against exactly one claimant, with reporting aligned to the GHG Protocol. Where a carrier runs a proprietary ledger that does not interoperate with others, the buyer should ask how the system prevents the same green-fuel tonne being claimed by the fuel producer, the carrier, and the cargo owner at once.

Credit quality is uneven, and the labels are recent. The ICVCM CCP-Approved label and the VCMI claim tiers were finalized in 2023 and are still being applied across credit categories; a credit predating those assessments carries no integrity assurance from either body. The greenhouse-gas-reduction figures and standard identifiers in this article are drawn from the cited primary sources and reflect the position through 2024; voluntary-market rules, the SBTi position, and national green-claims law are changing, and a buyer relying on a specific claim tier or methodology should check the current text of the source before acting.

Finally, the regulatory direction of travel constrains the whole market. National green-claims rules, the EU substantiating-green-claims proposal, and the SBTi scope-1 exclusion all narrow what a credit-based statement can say. A “carbon-neutral shipping” claim built primarily on offsets now carries reputational and legal exposure that did not exist before 2023.

Future outlook

By 2030 the voluntary credit market is expected to:

  • Have substantially reformed in line with the ICVCM CCPs and SBTi position.
  • Have shrunk as a share of total climate finance, from peak ~USD 2 billion in 2022 to ~USD 1 billion by 2030 (in real terms).
  • Have shifted toward removal credits (direct air capture + storage, biochar, enhanced rock weathering) and away from avoidance credits (REDD+, renewable energy).
  • Continue to play a niche role in shipping for residual emissions, book-and-claim arrangements and developing-country infrastructure projects.

The dominant maritime decarbonisation pathway will increasingly be direct fuel switching (LNG, methanol, ammonia, biofuel, hydrogen) supported by IMO Net-Zero Framework, EU ETS Maritime and FuelEU Maritime regulatory drivers, with voluntary credits as a complement rather than a primary tool.

See also

Additional calculators:

Additional related wiki articles:

References

  1. Verra. VM0028 Methodology for Reducing Emissions from Shipping. Verra, Washington, 2018.
  2. Gold Standard. Annual Report 2024. Gold Standard, Geneva, 2024.
  3. American Carbon Registry. Standards and Methodologies. ACR, Winrock International, 2024.
  4. Climate Action Reserve. Annual Report 2024. CAR, Los Angeles, 2024.
  5. Integrity Council for the Voluntary Carbon Market (ICVCM). Core Carbon Principles. ICVCM, March 2023.
  6. Science Based Targets initiative (SBTi). Position on the Use of Voluntary Carbon Credits in Scope-3 Emissions Claims. SBTi, April 2024.
  7. The Guardian, Die Zeit, SourceMaterial. Investigation: Phantom Forest Credits. January 2023.
  8. University of Cambridge. Voluntary Carbon Market Effectiveness Studies. 2022 to 2023.
  9. Maersk. ECO Delivery Service Annual Report. A.P. Møller-Mærsk, Copenhagen, annual editions 2020 to 2024.
  10. Trafigura. Sustainability Report 2024. Trafigura Group, Geneva, 2024.
  11. CMA CGM. ACT+ Service Annual Report. CMA CGM, Marseille, 2024.
  12. Hapag-Lloyd. Annual Sustainability Report 2024. Hapag-Lloyd, Hamburg, 2024.
  13. BIMCO. Voluntary Credit Guidance for Shipping Companies. BIMCO, Copenhagen, November 2024.
  14. International Chamber of Shipping. ICS Position on Voluntary Carbon Markets. ICS, London, 2024.
  15. European Commission. Proposal for a Directive on Substantiating Green Claims (Green Claims Directive). COM(2023) 166 final, March 2023.
  16. UK Competition and Markets Authority. Guidance on Environmental Claims in Marketing. CMA, London, 2024 update.
  17. California State Senate. AB 1305 (Voluntary Carbon Market Disclosures Act). Sacramento, 2024.
  18. Ecosystem Marketplace. State of the Voluntary Carbon Markets 2024. Forest Trends, Washington, 2024.
  19. McKinsey & Company. Voluntary Carbon Markets: Future Outlook to 2030. McKinsey, 2023.

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