Case study: Carbon markets & offsets integrity — a city or utility pilot and the results so far

When the City of Los Angeles launched its Carbon Offset Integrity Pilot in January 2024, officials expected a modest procurement exercise. Instead, the 18-month initiative exposed systemic quality gaps across the voluntary carbon market: of 2.4 million credits initially screened for municipal procurement, independent verification found that only 38% met the city's integrity criteria for additionality, permanence, and measurable co-benefits. The pilot, which ultimately retired 420,000 verified credits across six project categories, has become a reference model for how municipal and utility buyers can apply rigorous quality screening to offset portfolios without abandoning carbon markets entirely.

Why It Matters

North American cities and utilities represent a growing share of voluntary carbon market demand. A 2025 survey by the American Cities Climate Challenge found that 74 of the 100 largest US cities have adopted net-zero targets, with 52 of those explicitly including carbon credit procurement as part of their transition strategies (Bloomberg Philanthropies, 2025). Combined municipal and public utility offset procurement in the US reached $1.8 billion in 2024, up from $640 million in 2022, making the public sector the fastest-growing demand segment in the voluntary market.

Yet quality concerns have accelerated. Investigations by The Guardian, Die Zeit, and academic researchers at the University of Cambridge found that a significant share of credits from major registry programs, particularly avoided deforestation (REDD+) and large-scale renewable energy projects in countries with existing renewable mandates, did not deliver the emissions reductions they claimed. The Integrity Council for the Voluntary Carbon Market (ICVCM) released its Core Carbon Principles assessment framework in 2023, but adoption among municipal buyers has been slow due to limited internal capacity for credit evaluation and a fragmented market with over 170 accredited project methodologies across four major registries.

For founders building carbon market infrastructure, MRV platforms, or credit rating tools, understanding how a major city navigated these challenges reveals where the market's quality infrastructure is insufficient and where commercial opportunities exist.

Key Concepts

Additionality refers to whether a project's emissions reductions would have occurred without carbon credit revenue. This is the most contested integrity criterion. A forestry project in a region where logging is already economically unviable may generate credits for "avoided" emissions that were never at risk. The Los Angeles pilot required project-level additionality assessments using investment analysis, barrier analysis, or common practice tests aligned with the ICVCM Core Carbon Principles.

Permanence addresses whether sequestered carbon will remain stored for the credited time period. The pilot required a minimum 40-year permanence guarantee for nature-based credits, backed by buffer pool contributions of 15 to 25% of total issuance held in reserve against reversal events such as wildfires or land-use changes. For engineered removal credits (direct air capture, enhanced weathering), the permanence threshold was set at 1,000 years.

Co-benefits verification ensures that offset projects deliver measurable social and environmental outcomes beyond carbon reduction. The city required third-party verification of at least two co-benefits per project: biodiversity gains, community employment, improved air quality, water resource protection, or energy access improvements. Projects that could not document co-benefits through independent monitoring were excluded regardless of carbon integrity scores.

Registry transparency refers to the availability of project documentation, monitoring reports, and issuance data through public registries such as Verra, Gold Standard, American Carbon Registry, and Climate Action Reserve. The pilot found significant variation in documentation quality, with 22% of screened projects lacking publicly accessible monitoring reports for the most recent verification period.

What's Working

The Los Angeles Carbon Offset Integrity Pilot

The City of Los Angeles Bureau of Sustainability developed its pilot framework in partnership with the Rocky Mountain Institute and Sylvera, a carbon credit rating platform. The procurement process covered the city's residual emissions from municipal operations after direct reduction measures, targeting 420,000 tonnes of CO2 equivalent annually.

The screening methodology applied a three-tier evaluation. Tier 1 automated screening used Sylvera's credit-level ratings to eliminate credits rated below "A" on additionality and below "B" on permanence, reducing the initial pool of 2.4 million available credits to 910,000. Tier 2 expert review involved a panel of five independent carbon market specialists who evaluated project documentation, methodology appropriateness, baseline assumptions, and monitoring data for the remaining credits. This step eliminated a further 340,000 credits, with avoided deforestation projects accounting for 62% of rejections due to inflated baselines and questionable additionality. Tier 3 co-benefits verification used site visits and third-party audit reports to confirm claimed community and environmental outcomes, yielding a final portfolio of 420,000 credits across improved cookstove projects in Sub-Saharan Africa (35%), US-based methane capture from landfills (28%), reforestation projects in Latin America with indigenous community partnerships (22%), and biochar carbon removal projects in the Pacific Northwest (15%).

The final portfolio carried a weighted average price of $18.40 per tonne, compared to the $6.20 average for unscreened credits on the open market. The 197% price premium reflects the cost of quality: credits that survive rigorous integrity screening command significantly higher prices because supply at this quality tier is constrained.

The Regional Greenhouse Gas Initiative's Offset Reform

RGGI, the cap-and-trade program covering power sector emissions across 12 northeastern and mid-Atlantic states, reformed its offset provisions in 2024 after years of criticism that its original offset categories lacked robust MRV protocols. The reform reduced eligible offset categories from five to three (landfill methane capture, SF6 reduction from electrical equipment, and afforestation on marginal agricultural land) and introduced mandatory satellite-based monitoring for afforestation projects using data from Planet Labs and Pachama.

The reform resulted in a 45% reduction in offset supply available to RGGI compliance buyers, which contributed to a 30% increase in allowance prices during the second half of 2024. However, the remaining credits demonstrated measurably higher environmental integrity: a 2025 audit by the RGGI independent monitor found that 94% of post-reform offset credits delivered verified emissions reductions within 10% of their claimed volumes, compared to 71% under the previous framework (RGGI Inc., 2025).

Seattle City Light's Utility Offset Portfolio

Seattle City Light, the municipal electric utility serving 460,000 customers, restructured its carbon offset portfolio in 2023 to align with the Oxford Principles for Net Zero Aligned Carbon Offsetting. The utility shifted from a portfolio dominated by avoided emissions credits (renewable energy certificates and REDD+ credits) to one emphasizing carbon removal and high-permanence sequestration.

By mid-2025, the portfolio comprised 55% engineered removal credits (primarily from Climeworks direct air capture operations in Iceland and CarbonCure mineralization in concrete), 30% high-integrity nature-based removals (reforestation and soil carbon projects verified by the Climate Action Reserve with 25% buffer pool contributions), and 15% methane destruction credits from dairy biogas projects in Washington State. The average price per tonne increased from $8.50 in 2022 to $42.00 in 2025, but the utility's board approved the premium as consistent with its long-term net-zero strategy and ratepayer transparency commitments.

What's Not Working

Municipal capacity constraints remain a significant barrier. The Los Angeles pilot required 14 months of staff time from three full-time equivalents in the Bureau of Sustainability, plus $380,000 in consulting fees for expert reviewers and platform subscriptions. Smaller cities lack this capacity. A survey of 30 mid-sized US cities (population 100,000 to 500,000) by the Carbon Trust found that 83% had no dedicated staff for offset procurement and relied entirely on broker recommendations, which creates conflicts of interest when brokers earn commissions on credit volume rather than quality (Carbon Trust, 2025).

Registry data gaps complicate quality assessment. The pilot team found that 18% of Verra-registered projects and 12% of Gold Standard projects had monitoring report delays exceeding 18 months, making it impossible to verify recent performance. Additionally, registry systems do not consistently flag when project boundaries, baselines, or methodologies have been revised, requiring manual comparison of successive verification reports to detect material changes.

Offset-first strategies undermine climate ambition. Despite explicit policies prioritizing direct emissions reductions, three of the 12 city departments participating in the Los Angeles pilot initially proposed using offsets to cover emissions that could have been reduced through fleet electrification or building retrofits. The pilot team implemented a "mitigation hierarchy gate" requiring departments to demonstrate that offset procurement addressed only genuinely residual emissions, but enforcement relied on self-reporting and lacked independent verification.

Price volatility creates budget uncertainty for municipal buyers. High-integrity credit prices fluctuated between $14 and $28 per tonne during the pilot period, making multi-year procurement planning difficult. Unlike compliance markets with forward auction mechanisms, the voluntary market lacks standardized forward contracting infrastructure for quality-screened credits.

Key Players

Established organizations: Verra (largest voluntary carbon credit registry with over 1.9 billion credits issued), Gold Standard (registry emphasizing co-benefits verification and SDG alignment), Climate Action Reserve (North America-focused registry with robust US forestry and livestock methane protocols), RGGI Inc. (administrator of the northeastern US cap-and-trade program), Integrity Council for the Voluntary Carbon Market (governance body developing Core Carbon Principles for credit quality)

Startups: Sylvera (AI-powered carbon credit rating and due diligence platform used by the LA pilot), Pachama (satellite and LiDAR-based forest carbon MRV platform), BeZero Carbon (carbon credit ratings and analytics for institutional buyers), Renoster (carbon credit risk analytics specializing in permanence and reversal risk modeling), CarbonCure Technologies (concrete mineralization carbon removal integrated into building materials supply chains)

Investors: Generation Investment Management (anchor investor in multiple carbon market integrity platforms), Breakthrough Energy Ventures (backing engineered carbon removal technologies including direct air capture), Lowercarbon Capital (investing across carbon removal and MRV infrastructure), Microsoft Climate Innovation Fund (largest single corporate buyer of high-permanence carbon removal credits)

Action Checklist

• Establish a mitigation hierarchy gate requiring documentation that offset procurement covers only genuinely residual emissions after direct reduction measures
• Subscribe to at least one independent credit rating platform (Sylvera, BeZero, or Calyx Global) to supplement registry-level information
• Define minimum integrity thresholds for additionality, permanence, and co-benefits before entering the market rather than evaluating credits opportunistically
• Require monitoring reports dated within 12 months and reject credits from projects with reporting delays exceeding 18 months
• Allocate budget for a 150 to 200% price premium over unscreened market averages when planning high-integrity offset procurement
• Diversify across at least three project categories and two geographies to reduce concentration risk from reversal events or methodology invalidation
• Publish procurement criteria and portfolio composition publicly to build stakeholder confidence and contribute to market transparency
• Engage with ICVCM Core Carbon Principles adoption to signal demand for standardized quality benchmarks

FAQ

Q: How much more do high-integrity carbon credits cost compared to standard voluntary market credits? A: Based on the Los Angeles pilot and comparable municipal procurement data, credits that pass rigorous additionality, permanence, and co-benefits screening typically cost $15 to $45 per tonne, compared to $4 to $8 for unscreened credits. Engineered carbon removal credits (direct air capture, enhanced weathering) command $200 to $600 per tonne but are expected to decline to $100 to $150 by 2030 as capacity scales. Municipal buyers should budget for a 2 to 5x premium over benchmark voluntary market prices when targeting high-integrity credits.

Q: What percentage of voluntary carbon credits on the market meet high-integrity standards? A: Estimates vary, but converging evidence suggests that 30 to 50% of credits currently listed on major registries would pass comprehensive integrity screening comparable to the Los Angeles pilot's methodology. Sylvera's 2025 market analysis rated 34% of assessed credits as "A" or "AA" quality, while BeZero Carbon's ratings placed 41% in their top three quality tiers. The gap is concentrated in older vintage avoided deforestation and large-scale renewable energy credits, while newer methodologies for methane destruction, biochar, and engineered removal show significantly higher integrity rates.

Q: Can small cities implement offset integrity screening without the resources available to Los Angeles? A: Yes, but the approach must be simplified. Small cities can adopt the ICVCM Core Carbon Principles as a minimum threshold and purchase only CCP-labeled credits once that labeling program is fully operational. In the interim, subscribing to a single credit rating platform ($15,000 to $50,000 per year depending on volume) and limiting procurement to credits rated in the top quality tier provides 80% of the screening benefit at 20% of the cost. Pooled procurement through organizations such as the Urban Sustainability Directors Network or C40 Cities can further reduce per-city transaction costs.

Q: How should cities handle the risk of credit invalidation after purchase? A: Credit invalidation risk can be managed through portfolio diversification (no single project type exceeding 40% of total portfolio), purchasing from registries with buffer pool mechanisms that compensate buyers in reversal events, and including contractual clawback provisions in procurement agreements. The Los Angeles pilot maintained a 10% reserve allocation (purchasing 462,000 credits to retire 420,000) as self-insurance against potential invalidation. Additionally, buyers should monitor post-issuance project performance through annual verification report reviews.

Sources

• Bloomberg Philanthropies. (2025). American Cities Climate Challenge: Net Zero Target Tracker and Carbon Market Participation Survey. New York, NY: Bloomberg Philanthropies.
• RGGI Inc. (2025). Regional Greenhouse Gas Initiative 2024 Offset Reform: Implementation Report and Independent Audit Findings. New York, NY: RGGI Inc.
• Carbon Trust. (2025). Municipal Carbon Credit Procurement Practices: Capacity Gaps and Quality Risks in Mid-Sized US Cities. London: The Carbon Trust.
• Sylvera. (2025). State of Carbon Credits 2025: Quality Ratings, Market Trends, and Integrity Gaps. London: Sylvera Ltd.
• Integrity Council for the Voluntary Carbon Market. (2024). Core Carbon Principles Assessment Framework: Implementation Guide for Public Sector Buyers. London: ICVCM.
• City of Los Angeles Bureau of Sustainability. (2025). Carbon Offset Integrity Pilot: Final Report and Procurement Outcomes. Los Angeles, CA: City of Los Angeles.
• Seattle City Light. (2025). Carbon Neutrality Program: Annual Report on Offset Portfolio Composition and Performance. Seattle, WA: Seattle City Light.
• BeZero Carbon. (2025). Voluntary Carbon Market Quality Assessment: Ratings Distribution and Trend Analysis. London: BeZero Carbon Ltd.