American Carbon Registry (ACR): The First CCP-Labelled Registry & Winrock’s Integrity Incumbent

How ACR’s alignment-first strategy, four CCP-labelled methodologies, full CORSIA Phase 2 eligibility, and the Winrock ICE GreenTrace migration position it as the integrity incumbent in 2026.

By Abhishek Das • April 2026 • 13 min read

1. Why ACR Looks Different in the Integrity Era
2. The Winrock Context — Governance & Parent Organisation
3. First ICVCM CCP Program-Level Approval
4. The Four CCP-Labelled Methodologies
5. IFM Non-Federal US Forestlands v2.1 Deep-Dive
6. CORSIA Phase 1 & Phase 2 Eligibility
7. Paris Agreement Alignment & Article 6
8. ICE GreenTrace — The Registry Migration
9. Methodology Pipeline & What’s Next
10. Commercial Implications for Developers & Buyers
11. Frequently Asked Questions
12. What Project Developers Should Do Now

Why ACR Looks Different in the Integrity Era

If you have been tracking Verra’s VCS v5.0 overhaul or Gold Standard’s mandatory Paris Agreement alignment transition, you may have noticed something conspicuously absent: a comparable sweeping reform from the American Carbon Registry (ACR). That absence is not a story of inaction — it is the story of a registry that did the work earlier, held a tighter portfolio, and arrived at the 2026 Era of Integrity already positioned where its peers are now scrambling to stand.

ACR operates a deliberately narrow methodology portfolio relative to Verra. Where Verra maintains dozens of active methodologies spanning AFOLU, energy, industry, transport and waste, ACR has historically concentrated on a small number of high-confidence methodology families. This architectural choice has a compounding effect: fewer methodologies means less surface area to align, shorter revision cycles, and a programme that can absorb new integrity requirements by updating individual methodologies rather than rewriting the rulebook.

ACR also started aligning with Paris Agreement principles before the Integrity Council for the Voluntary Carbon Market (ICVCM) Core Carbon Principles framework was even finalised. When the ICVCM assessment process opened in 2023 and moved into program-level decisions in 2024, ACR was one of the first candidates ready — and in April 2024 it became the first registry in the world to receive a positive ICVCM program-level CCP decision, and the first to have a specific methodology designated as Paris Agreement-aligned.

The Winrock Context — Governance & Parent Organisation

ACR is operated by Winrock International, a non-profit organisation founded by Winthrop Rockefeller with a mission spanning agricultural development, natural resource management and environmental markets. Winrock’s carbon markets experience runs deep: the organisation launched the Environmental Resources Trust (ERT) registry in 1996, pre-dating most modern voluntary carbon market infrastructure. ACR as it exists today emerged from that heritage and has operated continuously as a registry since 1996, making it the oldest voluntary greenhouse gas registry in the world.

The governance model matters because it shapes incentives. As a non-profit, Winrock is insulated from the shareholder pressures that can push a standard towards quantity over quality. The ACR programme is overseen by a scientific advisory committee, and methodology approvals follow a published public consultation process. This governance structure has produced a registry that moves more slowly on methodology additions than its commercial peers — and that is precisely the attribute the integrity era now rewards.

The Winrock twin relationship with ART (Architecture for REDD+ Transactions) deserves a note here. Both ACR and ART sit under Winrock’s Environmental Resources Trust umbrella. They are separate standards with separate governance and separate methodology rulebooks — ACR handles project-scale crediting across multiple sectors while ART specialises in jurisdictional REDD+ — but they share operational infrastructure, and both are migrating to the ICE GreenTrace registry platform in Spring 2026. Buyers and developers working across both standards benefit from aligned account structures and shared operational teams.

First ICVCM CCP Program-Level Approval

The ICVCM Core Carbon Principles (CCP) framework is the closest thing the voluntary carbon market has to a unified quality standard. It consists of ten principles spanning governance, emissions impact and sustainable development, and it is applied in two stages: first at the program level (the registry/standard itself), and then at the category/methodology level. Only credits issued under a CCP-labelled methodology, on a CCP-approved programme, can be retired with the CCP tag.

In April 2024, the ICVCM Assessment Platform announced that ACR had become the first independent carbon crediting program to receive a positive program-level CCP decision. This decision confirmed that ACR’s governance, procedural integrity, transparency, and enforcement mechanisms meet the CCP requirements. Program-level approval does not by itself make any particular credit CCP-labelled — that still requires the underlying methodology to be approved separately — but it is the necessary precondition. Every CCP-labelled credit must come from a CCP-approved programme.

At the same time as its program-level approval, ACR also became the first standard to have a specific methodology designated as Paris Agreement-aligned by the ICVCM. That first-mover position matters for two reasons: it gives ACR credits the longest CCP track record of any registry, and it signals to regulators, buyers and ratings agencies that the programme has been operating to integrity era standards longer than its peers. For buyers building CCP-labelled portfolios, the ACR back-catalogue offers more eligible vintages than most other standards.

The Four CCP-Labelled Methodologies

As of early 2026, four ACR methodologies carry the ICVCM Core Carbon Principles label. These cover both avoidance and removal credit types, across industrial, waste and forestry sectors. Together they represent the backbone of ACR’s CCP-labelled issuance pipeline.

Each CCP label is attached to a specific methodology version. Credits issued under an older, non-labelled version of the same methodology remain valid ACR credits but cannot be retired with the CCP tag. Buyers must check the methodology version and the issuance date to confirm CCP eligibility, and registries publish this information alongside the serial number range of each issuance.

IFM Non-Federal US Forestlands v2.1 Deep-Dive

ACR’s Improved Forest Management (IFM) on Non-Federal US Forestlands is the programme’s flagship forestry product and one of the most scrutinised methodologies in the US voluntary market. Version 2.1, published in 2024, addresses many of the additionality, baseline and leakage concerns that have dogged earlier generations of forest carbon methodologies. ICVCM conditionally approved v2.0 under the CCPs, and ACR has indicated that v2.1 will carry the full label once the conditional requirements are resolved.

The programme enrols approximately 18 registered project activities spanning roughly 500,000 acres of privately owned and tribally owned forestland across the United States. Project activities are diverse: extended harvest rotations, conversion to uneven-aged management, reduced-impact logging, and permanent conservation easements. The methodology applies only to non-federal land — federal forestland is excluded — which keeps the programme focused on private and tribal owners who would otherwise have limited access to carbon finance.

Key v2.1 refinements include a tightened additionality test based on regional harvest benchmarks, explicit discounting for potential activity-shifting leakage to nearby forests, a risk-weighted buffer pool contribution calculated from wildfire and disturbance probability, and long-term monitoring requirements. The buffer pool is ACR’s primary mechanism for managing reversal risk — if a wildfire or pest outbreak reverses stored carbon, credits are retired from the pooled buffer to restore integrity without penalising the affected project.

CORSIA Phase 1 & Phase 2 Eligibility

The ICAO Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) is the second pillar of ACR’s integrity positioning. In early 2024, the ICAO Technical Advisory Body (TAB) recommended ACR for CORSIA Phase 1 (2024–2026), and subsequently extended that recommendation to Phase 2 (2027–2029). Phase 2 eligibility is significant because it is broader than Phase 1: all of ACR’s actively operating methodologies are eligible under the Phase 2 approval, whereas Phase 1 was restricted to a narrower methodology set.

CORSIA eligibility is not automatic for individual credits. A credit must meet three layered requirements: the methodology must be on the ICAO eligible list, the project start date and vintage year must fall within the CORSIA eligibility window for the Phase, and the host country must have granted the necessary letter of authorisation confirming corresponding adjustments (Letter of Authorisation – LOA). Airlines sourcing credits for CORSIA compliance should therefore always cross-check the ICAO eligible-unit list rather than relying on a general “CORSIA-eligible” label on the registry.

For project developers, Phase 2 eligibility expands the addressable market. ACR credits from previously-non-CORSIA-eligible methodologies will become eligible for 2027+ vintages, subject to host country authorisation. This is particularly relevant for developers with IFM and A/R projects who have historically been excluded from CORSIA demand.

Paris Agreement Alignment & Article 6

ACR’s Paris Agreement alignment strategy differs from Gold Standard’s. Where Gold Standard is running a mandatory, all-portfolio transition to PA-aligned methodologies with a hard 1 January 2026 vintage cutoff, ACR has taken an incremental, methodology-by-methodology approach. The programme was the first to have a methodology designated as Paris Agreement-aligned by the ICVCM, and subsequent methodology revisions are being aligned as they move through the normal update cycle.

For Article 6.2 cooperative approaches, ACR credits can be used subject to host country authorisation and the standard corresponding adjustment requirements. For the Article 6.4 Mechanism (PACM, the UNFCCC-operated successor to CDM), ACR is not itself a host registry but ACR-eligible project activities may transition or be dual-registered depending on host country choice. The practical bottleneck for both pathways is host country readiness: most tropical forest countries that could host ACR IFM or A/R projects have not yet published their full Article 6 authorisation frameworks.

The practical implication for developers: if your project is based in the United States (as most ACR IFM and landfill gas projects are), Article 6 is not currently a relevant pathway because the US has not yet signalled intent to authorise corresponding adjustments for voluntary carbon projects on its territory. For projects in Article 6-ready host countries, ACR’s PA-alignment provides the methodology layer, but the host country layer remains the critical path.

ICE GreenTrace — The Registry Migration

The most operationally significant event on the ACR 2026 calendar is not a methodology revision — it is an infrastructure migration. In Spring 2026, Winrock’s Environmental Resources Trust, the operator of the ACR and ART Registry, is migrating account holdings and issuance infrastructure to ICE GreenTrace, a next-generation carbon registry platform developed by Intercontinental Exchange (ICE). Winrock is ICE’s launch partner for GreenTrace, and the migration will run both ACR and ART accounts onto the same platform while preserving each standard’s independent governance and methodology rulebook.

ICE GreenTrace is designed as an enterprise-grade registry infrastructure with four headline features: real-time issuance and retirement updates, APIs that expose issuance and retirement data to third-party applications (marketplaces, ratings providers, ESG reporting tools), an enterprise audit trail that links project documents to the serial-number level, and a settlement layer that enables atomic credit transfers similar to financial market infrastructure. For buyers integrating ACR credits into ESG disclosures or corporate compliance systems, the API layer alone is a meaningful upgrade over polling-based integrations.

The migration is being managed with a parallel-access window during the cutover. Existing ACR account holders will receive migration instructions directly from Winrock, and all historical issuances, retirements and serial numbers will be preserved through the transition — no re-serialisation, no loss of provenance. Account credentials will be re-issued on the new platform, and API keys for the legacy registry will be migrated or re-issued as part of the process. A Q1 2026 preview webinar is planned for marketplaces, ratings providers and high-volume buyers.

Methodology Pipeline & What’s Next

Beyond the four currently CCP-labelled methodologies, ACR maintains an active methodology pipeline covering additional sectors that fit its integrity-first positioning. Methodology revisions and new approvals work through ACR’s public stakeholder consultation process, with drafts published for comment before the Scientific Advisory Committee reviews and the board approves. ACR has signalled that additional methodologies are under active ICVCM assessment as part of the ongoing CCP category-level review.

Where ACR is most likely to add new methodology footprint in 2026–2027 is at the intersection of removal credits and the ICVCM’s ongoing category assessments. Durable removal categories (mineralisation, bio-oil sequestration, enhanced rock weathering) are areas where ACR’s compact governance and scientific advisory structure are well-suited to rapid methodology development. The trade-off is volume: ACR is unlikely to chase large-volume AFOLU categories that have had integrity concerns flagged by ICVCM, Science Based Targets, or the Voluntary Carbon Markets Integrity Initiative.

The practical read for 2026: expect ACR to issue additional CCP-labelled methodologies on the existing portfolio, expect tightening of additionality and leakage parameters within the IFM and A/R families, and expect continued refinement of the buffer pool risk-rating approach. Do not expect a sweeping v5-style restructuring — it would be architecturally inconsistent with how ACR has always operated.

Commercial Implications for Developers & Buyers

For project developers, ACR offers a distinct value proposition in 2026: a stable methodology portfolio, a first-to-CCP track record, and Phase 2 CORSIA eligibility across all active methodologies. The trade-off is scope — if your project type is outside the four CCP-labelled methodologies, you will need to decide whether to wait for ACR to approve a new methodology or register on a registry with an existing methodology (typically Verra). For US forestland and landfill gas developers, ACR is often the default choice because the methodology fit is already CCP-labelled.

For buyers, ACR credits offer three pricing tiers: CCP-labelled credits (premium pricing, growing share of retirements), non-CCP-labelled ACR credits (standard voluntary pricing), and CORSIA-eligible ACR credits (which may trade at a distinct compliance-driven price when the airline compliance window opens). The forthcoming ICE GreenTrace migration will improve price discovery by exposing issuance and retirement data to marketplaces and ratings providers in real time, narrowing the bid-ask spread particularly for CCP-labelled vintages.

Credit volumes for 2026+ are expected to grow modestly. ACR is not aggressively expanding its methodology portfolio, which limits supply growth, but existing projects are continuing to verify and issue. The IFM Non-Federal US Forestlands programme is the largest single driver of new removal credit supply, with the pipeline of enrolled projects continuing to grow through 2026–2027. Buyers planning multi-year CCP-labelled retirement strategies should engage directly with ACR-registered project developers rather than relying on spot market availability.

Frequently Asked Questions

These are the questions that come up most often when project developers and corporate buyers consider ACR as a primary or supplementary registry for their 2026 carbon strategies.

What Project Developers Should Do Now

ACR’s stability does not mean there is nothing to do. Here is the practical checklist for project developers and corporate buyers through the first half of 2026:

(1) Confirm your methodology version and CCP status. Pull the current version of the methodology you are verifying under and confirm whether it is CCP-labelled. If it is not but the underlying methodology family is labelled, review whether re-verification under the current version is commercially justified — CCP-labelled retirements command premium pricing.

(2) Prepare for ICE GreenTrace migration. Winrock will communicate migration instructions directly to existing account holders. Review your internal systems for API dependencies on the legacy registry, plan for parallel-access testing during the cutover window, and update any integration that parses serial numbers.

(3) Review CORSIA Phase 2 eligibility. If your project is on a methodology that was not CORSIA-eligible under Phase 1 but is eligible under Phase 2, engage airline buyers early. Confirm your project start date and vintage year fall within the Phase 2 eligibility window and that your host country is prepared to issue the necessary authorisation letter.

(4) Budget for IFM v2.1 transition if applicable. For US forestland developers, confirm whether your project is on v2.0 or v2.1, and budget for the additionality, leakage and buffer pool recalculation if you are upgrading. New projects should use v2.1 from the start.

(5) Engage forward-sale counterparties. Buyers building CCP-labelled portfolios are increasingly writing CCP-label delivery clauses into forward contracts. If you have pre-sold ACR credits, review whether your forward contracts reference the CCP label and whether your methodology version meets that contractual specification.

(6) Monitor the ICVCM assessment pipeline. Additional ACR methodologies are under active ICVCM category-level review. Outcomes through 2026 will determine which additional ACR methodologies receive the CCP label — staying informed helps you anticipate which project types will command premium pricing next.

(7) Coordinate with ART if you operate at both scales. Project developers who operate at both project scale (ACR) and jurisdictional scale (ART) should use the shared Winrock ERT account structure to coordinate cross-standard reporting and avoid double-counting. The ICE GreenTrace migration will simplify this in Spring 2026.