The Market That Lost Its Credibility Is Building New Infrastructure to Get It Back
The voluntary carbon market, the system of private market transactions in which companies purchase carbon credits representing greenhouse gas emission reductions or carbon removals to offset their own emissions and support their net-zero claims, entered its most severe credibility crisis in a generation between 2023 and 2025 when a series of investigative journalism exposés, academic studies, and regulatory investigations documented the systematic overstatement of emission reductions from the forest protection projects that had dominated voluntary carbon credit supply. The Guardian and Zeit's January 2023 investigation into Verra's REDD+ forest protection methodology, which found that over ninety percent of the forest protection carbon credits from the world's largest VCM standard organisation's flagship programme had not actually prevented the deforestation they claimed, triggered the reputational collapse that wiped approximately sixty to seventy percent of value from voluntary carbon credit prices between early 2023 and late 2024, caused major corporate buyers including Shell, Nestlé, and Gucci to publicly withdraw from voluntary carbon offset commitments they had previously announced, and precipitated the resignations of senior executives at South Pole, the world's largest carbon credit project developer, amid accounting irregularities at its Kariba REDD+ project in Zimbabwe. The market that emerged from this credibility destruction is structurally different from the one that entered it: the nature-based credits whose measurement, reporting, and verification had relied on satellite-based deforestation models whose assumptions the investigations challenged are being replaced or supplemented by the technology-based removals whose physical measurement and permanence is more directly verifiable, the corporate net-zero claims that had relied on cheap nature-based offset purchasing are being reformulated under the Science Based Targets initiative's net-zero standard whose scope restrictions and residual emissions coverage limits have significantly reduced the role of offsets in corporate decarbonisation strategy, and the market infrastructure whose rating agencies, integrity standards, and disclosure frameworks had been absent is now under construction.
The voluntary carbon market, measured in terms of credit issuance volume, declined from a peak of approximately five hundred million tonnes of CO2 equivalent in 2021 to approximately one hundred and fifty to two hundred million tonnes in 2025 before stabilising, and is projected to recover toward three hundred to four hundred million tonnes by 2027 as the new integrity infrastructure restores buyer confidence. The recovery is not expected to be uniform across credit types: technology-based removals including direct air capture, biochar, enhanced rock weathering, and blue carbon are capturing a disproportionate share of the recovering corporate buyer demand whose quality premium for measurement-certainty credits is wider than it was before the crisis, while nature-based credits are expected to recover more slowly as the new methodologies for their verification are established through the new Verra and Gold Standard methodology revisions and as the Article 6.4 mechanism creates the international compliance framework that provides the governance legitimacy that the purely voluntary market lacked.
Article 6.4 and the COP31 Finalization
The Paris Agreement's Article 6.4, the mechanism that establishes the UN-supervised international carbon market whose credits, designated as Article 6.4 Emission Reductions or A6.4ERs, are intended to function as internationally recognised compliance instruments rather than voluntary market credits, has been under development since COP21 in 2015 and has made the most progress toward operational functionality in the 2024 to 2026 period. The Article 6.4 Supervisory Body, established at COP26 in Glasgow and operationalised through subsequent COP decisions, has developed and is seeking COP31 approval for the methodology requirements, removal activity standards, and baseline setting approaches that will determine what types of emission reduction and removal projects can generate Article 6.4 credits, what measurement and verification standards they must meet, and how their credits will be adjusted for the Corresponding Adjustments that prevent double-counting between the host country's nationally determined contribution and the international credit buyer's use. COP31 in Antalya, Turkey from November 9 to 20 2026, which is six weeks away from today, is the scheduled decision point for the Article 6.4 methodology approvals that would allow the first A6.4ER-generating projects to be registered and to begin credit issuance, creating the international compliance credit whose ICAO-aligned accounting would make it acceptable for international aviation's CORSIA obligations and whose UN supervision would provide the governance legitimacy that the voluntary market's methodological controversies had eroded.
South Pole, the Swiss carbon project developer and trading company whose Kariba REDD+ project controversies and senior executive departures made it the most commercially damaged major player from the 2023 to 2025 credibility crisis, has repositioned its business model toward the project advisory and carbon management consulting revenue that does not depend on the proprietary credit issuance whose reputational risk the Kariba investigation created. BeZero Carbon and Sylvera, the UK carbon credit rating agencies whose independent assessment of credit quality provides the buyer due diligence infrastructure that the VCM's absence of credit ratings had previously required buyers to supply through their own expensive project-level due diligence, have emerged as the critical market infrastructure whose rating coverage of the recovering VCM's credit supply is the buyer confidence signal that the recovering market requires to enable carbon credit purchasing at scale without project-level due diligence burden.
The VCMI Claims Code and the Demand Signal
The Voluntary Carbon Markets Integrity Initiative's Claims Code of Practice, whose 2023 publication established the buyer-side integrity standard for how companies can credibly use voluntary carbon credits in their climate claims without misleading investors or consumers, is the demand-side market infrastructure whose adoption by major corporate buyers determines what types of credits and what claims they support as legitimate corporate decarbonisation communication. The VCMI Claims Code's tiered approach, which allows companies to make climate contribution claims reflecting the beyond-value-chain mitigation they are funding rather than the offset accounting that the earlier voluntary market's net-zero claims implied, is creating the demand signal for high-integrity credits whose quality premium supports the technology-based removal and Article 6.4 credit prices that make the most verifiable emission reduction projects commercially viable.
Top 10 Companies in Voluntary Carbon Markets, Article 6, and Carbon Credit Integrity Globally
- Verra: US carbon standard organisation with Verified Carbon Standard and ongoing REDD+ methodology revision; its methodology reform programme and its market standard role create the carbon standard whose post-controversy reform is the most commercially critical for VCM recovery because the majority of previously issued nature-based credits were Verra-certified and the credibility of future nature-based credit supply depends on Verra's reformed methodology standards.
- Gold Standard: Swiss carbon standard with SDG-linked project certification competing with Verra; its sustainable development integration and its Swiss institutional backing create the carbon standard whose smaller but more selective credit registry positions it as the premium alternative to Verra for the corporate buyers whose quality preference over volume is driving the bifurcation in VCM buyer preferences post-crisis.
- BeZero Carbon: UK carbon credit rating agency with independent quality assessment of voluntary carbon credits; its project-level risk scoring and its institutional investor client base create the credit rating infrastructure whose independent assessment of credit quality enables carbon credit purchasing decisions without requiring the project-level due diligence that only the largest corporate buyers can resource independently.
- Sylvera: UK carbon credit rating company with data-driven project quality assessment; its satellite data integration and its credit scoring create the competing credit rating infrastructure whose quantitative approach to VCM credit quality assessment provides the buyer due diligence alternative to BeZero's more qualitative risk framework, creating the multiple independent ratings that a mature credit market requires.
- South Pole: Swiss carbon project developer and advisor repositioned toward carbon management consulting; its project development expertise and its post-Kariba business model pivot create the carbon company whose reputational rehabilitation and advisory revenue model represent the VCM industry's most commercially significant recovery story whose success or failure signals whether the project development business model can survive the credibility crisis.
- Climeworks: Swiss direct air capture company with Mammoth Iceland DAC plant producing the highest-integrity carbon removal credits; its physical carbon removal verification and its corporate offtake agreements with Microsoft, Boston Consulting Group, and others create the technology removal company whose credits command the highest price in the VCM because their measurement certainty and permanence are the furthest from the nature-based credit controversies.
- VCMI (Voluntary Carbon Markets Integrity Initiative): UK-international initiative with Claims Code of Practice for corporate VCM use; its demand-side integrity framework and its corporate adopter network create the market infrastructure whose buyer-side standard is the complement to Verra's and Gold Standard's supply-side integrity frameworks, together creating the integrity architecture whose absence created the VCM credibility crisis.
- Xpansiv: US carbon and environmental commodity exchange with CBL carbon trading platform; its voluntary carbon credit trading infrastructure and its digital MRV integration create the exchange whose market liquidity and price discovery for VCM credits provide the financial market infrastructure that the recovering VCM requires for institutional buyers to size and manage carbon credit positions with the same tools they apply to other commodity trading.
- Pachama: US nature-based carbon project developer with satellite verification of forest carbon; its satellite and machine learning forest monitoring and its Amazon and other forest project portfolio create the nature-based carbon developer whose technology-driven verification approach most directly addresses the monitoring inadequacy that the Verra REDD+ investigations identified as the root cause of the credit quality crisis.
- CarbonPlan: US carbon market research organisation with independent assessment of carbon credit integrity; its academic-standard project quality research and its public database of credit quality assessments create the non-commercial research organisation whose independent methodology analysis has been the most influential source of the evidence base that has driven VCM methodology reform, providing the analytical credibility that industry-funded research organisations cannot claim.