Carbon Ratings Methodology
This document sets out how SYNE constructs, weights, scores, and governs a Carbon Rating for carbon credit projects, issuers, and carbon-intensity performance. It covers scope, data sources, the full criteria framework, grade assignment, governance, review cycle, and appeals.
Twelve sections, start to finish.
Scope & Applicability
Who is eligible to be rated, and how a rating is commissioned.
02Data Sources & Collection
Registry documents, field verification, and third-party data.
03Carbon Market Principles
Additionality, permanence, leakage and double-counting, explained.
04Criteria Framework
80 criteria across additionality, permanence, MRV and co-benefits.
05Weighting & Scoring Methodology
How individual criterion scores combine into one composite score.
06Data Quality Adjustment
Why a score needs verified MRV data to reach the top grade bands.
07Continuous Monitoring
Ongoing satellite and registry surveillance between review cycles.
08Grade Assignment & Rating Scale
How the composite score maps to the shared AAA–D scale.
09Mapping to the SYNE Index
How this rating becomes a position on the two-axis Index.
10Governance & Independence
Who signs off on a rating, and how conflicts are managed.
11Review Cycle, Triggers & Appeals
When ratings are revisited, and how to challenge one.
12Limitations & Version History
What this rating does not do, and how the methodology has changed.
Who and what this methodology rates.
This methodology applies to carbon credit projects, carbon credit issuers, and carbon-intensity performance assessments, across voluntary and compliance carbon markets and any of SYNE's 71 licensed jurisdictions. It does not apply to corporate ESG performance, which falls under the ESG or Sustainability Ratings Methodology, or to suppliers, which fall under the Supplier Ratings Methodology.
A project becomes eligible for a Carbon Rating once it has a registered methodology with a recognised registry (such as Verra VCS or Gold Standard), or has submitted an equivalent feasibility and baseline package directly to SYNE for pre-issuance assessment. Ratings can be commissioned by the project developer or issuer, or requested by a prospective buyer or investor with the developer's cooperation.
At a glance
- Applies to
- Carbon credit projects, issuers & carbon-intensity assessments
- Minimum eligibility
- Registered registry methodology, or an equivalent feasibility & baseline package
- Commissioned by
- The project developer or issuer, or a prospective buyer with cooperation
- Geographic scope
- Any of SYNE's 71 licensed jurisdictions
- Excludes
- Corporate ESG performance and suppliers - see the respective methodologies
Where the underlying evidence comes from.
Every Carbon Rating draws on registry documentation, independent geospatial verification, licensed market data, and independent third-party data, weighted toward independently verifiable evidence wherever possible.
Registry documentation
Project design documents, monitoring reports, and validation/verification (VVB) reports filed with the registry.
Geospatial & field verification
Satellite and remote-sensing analysis, cross-referenced with SYNE's Biomass Atlas, plus field verification data where available.
Independent data providers
Data from accredited VVBs, satellite imagery providers, and standards bodies, sourced independently of the project developer.
Licensed market & pricing data
Carbon pricing and trading data licensed through SYNE Data and Carbon Intelligence, used to contextualise market-wide performance.
The core concepts every criterion is built on.
Before scoring a single criterion, every analyst applies the same four industry-standard concepts that underpin credible carbon accounting. These aren't SYNE-specific definitions - they're the same principles referenced in the GHG Protocol, IPCC guidance, and the ICVCM Core Carbon Principles.
Would it have happened anyway?
Whether the emissions reduction or removal is genuinely caused by the project, and would not have occurred under a business-as-usual baseline.
How long does it last?
How durable a reduction or removal is, and the reversal risk that stored carbon could later be released back into the atmosphere.
Did it just move elsewhere?
Whether emissions reduced in one place are genuinely avoided, or simply displaced to a location outside the project boundary.
Is it claimed only once?
Ensuring the same tonne of avoided or removed carbon isn't claimed by more than one party, registry, or country's national inventory.
80 weighted criteria across four dimensions.
Each criterion is scored on a normalised 0–100 basis by a lead analyst, using a documented scoring rubric aligned to GHG Protocol, IPCC guidance, and the ICVCM Core Carbon Principles, before dimension and composite scores are calculated.
Additionality & Baseline
Whether the emissions reduction or removal is real, and beyond what would have happened anyway.
- Baseline Scenario Construction
- Regulatory & Financial Additionality Test
- Leakage Risk Assessment
- Double-Counting & Registry Cross-Checks
Permanence & Reversal Risk
How durable the emissions reduction or removal is, and what could reverse it.
- Reversal Risk Assessment
- Buffer Pool Contribution Adequacy
- Monitoring Period Length
- Legal Title & Land Tenure Security
MRV & Data Integrity
Measurement, reporting and verification quality - including satellite and field data.
- Satellite & Remote Sensing Verification (Biomass Atlas)
- Field Measurement Protocol Quality
- Third-Party Validation & Verification (VVB)
- Data Transparency & Traceability
Co-benefits & Safeguards
Biodiversity, community and social impact beyond the carbon claim itself.
- Biodiversity & Ecosystem Co-benefits
- Community Consent & Benefit-Sharing
- Environmental & Social Safeguards
- SDG Alignment
How 80 individual scores become one number.
Each of the 80 criteria carries a base weight set by project-type materiality mapping, reviewed annually against evolving registry methodologies. Criterion scores are aggregated into a dimension score using the weighted average of that dimension's criteria, and dimension scores are then combined into the composite score using the dimension weights shown in Section 04.
Project-type materiality mapping
Criterion weights are adjusted by project type - for example, permanence criteria carry more weight for a forestry project than for a renewable energy project.
Weighted average, not simple average
No criterion is dropped for missing data; a missing criterion is scored as zero unless a documented exemption applies, preventing silent grade inflation.
Non-compensatory floors
No project can reach AAA or AA without independently verified MRV data - a strong additionality claim on unverified data caps the composite score.
A strong score on unverified MRV data isn't a strong rating.
Every criterion score carries a parallel data quality flag - Assured, Disclosed, or Estimated - based on the strength of its underlying evidence. A composite score cannot reach the AAA or AA band unless at least 80% of its criteria carry an Assured or Disclosed data quality flag, and no more than 10% are flagged Estimated.
Independently verified
Backed by third-party VVB verification, satellite cross-checks, or an independently verifiable registry record.
Developer-disclosed, unassured
Reported directly by the project developer without independent assurance, but consistent with other available evidence.
Modelled or inferred
Estimated using methodology defaults or regional proxies where direct monitoring data isn't yet available.
What happens between scheduled review cycles.
A rating is not frozen for a full year between reviews. Continuous monitoring tracks satellite and registry signals that could affect a project's score in real time, feeding into the interim review triggers described in Section 11.
Satellite & remote sensing alerts
New deforestation, fire, or land-use change signals are flagged as they're detected, not held until the next scheduled review.
Quarterly registry data refresh
Registry issuance, retirement, and monitoring report data refreshes at least quarterly.
Threshold-based escalation
A monitoring signal that crosses a defined materiality threshold is escalated to the Rating Committee for an interim review decision.
How the composite score becomes a letter grade.
The composite score, after data quality adjustment, is mapped to the six-tier AAA–D scale shared across every SYNE product.
Requires Assured data quality on at least 80% of criteria, per Section 06.
Requires Assured or Disclosed data quality on at least 80% of criteria.
Material gaps identified in permanence or MRV, being actively addressed.
Significant improvement needed in baseline, permanence or verification.
Fundamental gaps in additionality or measurement integrity.
No material evidence of genuine, verifiable emissions impact.
How this rating becomes a point on the Index.
The SYNE Index plots every rating on two axes: Standards Alignment and Data Quality & Assurance. For Carbon Ratings, the Standards Alignment axis is derived from the weighted average of the Additionality & Baseline, Permanence & Reversal Risk, and Co-benefits & Safeguards dimension scores; the Data Quality & Assurance axis is derived directly from the MRV & Data Integrity dimension and the data quality flags described in Section 06. See the SYNE Index Methodology for the full cross-product calculation.
Front Runners
Strong additionality, permanence and co-benefits, backed by rigorously verified MRV data.
Rising Stars
Strong project fundamentals, with MRV verification depth still maturing.
Emerging Stars
Rigorously verified data, applied to a narrower additionality or permanence case.
Backmarkers
Weak additionality or permanence case, with limited or unverifiable MRV data.
Who signs off on a rating, and how conflicts are managed.
Independent Rating Committee
A committee separate from the lead analyst reviews and approves every rating before publication.
No pay-for-rating influence
Fees are agreed before an engagement begins and have no bearing on the rating outcome; analysts hold no financial interest in rated companies.
Factual accuracy review only
Rated companies may review a draft rating once, strictly for factual accuracy - not to negotiate the score.
When a rating is revisited, and how to challenge one.
Annual review
Every rating is fully reassessed at least once every 12 months, aligned to the company's own reporting cycle where possible.
Interim review triggers
A material controversy, restatement, M&A event, or leadership change can trigger an interim review ahead of the next scheduled cycle.
Factual accuracy window
Rated companies have 10 business days from draft delivery to raise a factual accuracy challenge before a rating is finalised.
What this rating does not do.
A Carbon Rating is an opinion of a project's or issuer's carbon integrity as of the rating date - it is not a guarantee that credits will be issued, a price forecast, or an investment recommendation. It relies on registry documentation, field data and geospatial analysis available at the time, and cannot detect fraud or concealment that no available evidence would reveal.
| Version | Effective date | Summary of changes |
|---|---|---|
| v2.1 | Jul 2026 | Added Carbon Market Principles and Continuous Monitoring sections; added independent third-party data as a distinct source category. |
| v2.0 | Jan 2026 | Introduced the non-compensatory MRV data quality floor; expanded Biomass Atlas geospatial integration. |
| v1.1 | Jan 2025 | Added Co-benefits & Safeguards as a standalone dimension, previously scored within Additionality. |
| v1.0 | Jan 2023 | Initial publication of the Carbon Ratings Methodology. |
This document is available in full, including prior versions, on request as part of SYNE's regulatory disclosure pack. For questions about how a specific criterion is scored, contact SYNE's methodology team.
See how this methodology applies to your project.
Talk to our team about commissioning a Carbon Rating, or request a pre-issuance feasibility assessment first.