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Rating the raters: Assessing the quality of carbon credit rating agencies

The study ‘Assessing and comparing carbon credit rating agencies’ has assessed the performance of four major carbon credit rating agencies (BeZero, Calyx, Renoster and Sylvera). The study highlights discrepancies among agencies’ assessments by evaluating approaches to additionality, non-permanence risks, leakage risks, and co-benefits and safeguards. It has been commissioned by Carbon Market Watch and conducted by Perspectives Climate Group.

Carbon credit rating agencies are organisations that assess and rate the quality of carbon credits in the voluntary carbon market (VCM). These agencies develop and use their own frameworks to comprehensively and impartially evaluate the likelihood that a carbon credit truly represents a tonne of CO2e that has been reduced or removed by a project.

Whilst their actions support a drive for higher integrity in the market, confusion is routinely created due to assessments of the same projects being starkly different. At worst, this risks legitimising the use of low-quality carbon credits. The conclusion is that approaches to rate carbon credit quality are generally well thought out, even though there is still some room for improvement.

CMW’s recommendations for carbon credit rating agencies:

  • Reversal risk should be assessed over a 100-year period.
  • Provide different non-permanence ratings based on credit vintages.
  • If you can’t measure leakage, don’t assume it’s 0.
  • The additionality score should be the maximum score a project can get.
  • Co-benefits should be assessed for any project, based on the SDGs.
  • Safeguards ratings should be incorporated into the credit quality score.
  • Frameworks should be publicly available.
  • Some ratings should be publicly available.
  • Install a strong policy that monitors developments and sets a timeframe for updates of ratings.

CMW’s recommendations for buyers:

  • Don’t shoot the messenger. Strict rating frameworks by design assess risks more thoroughly. Don’t focus blame on rating agencies for low scores, but rather on low-scoring projects for their shortcomings.
  • Engage with ratings. Try to understand what the rating truly means by looking at the scaling system and being careful with provisional ratings.
  • A tonne is not a tonne. Don’t use carbon credits to claim carbon neutrality.



This briefing was supported by Brot für die Welt (BfdW) and the EU’s Life programme. The content does not necessarily reflect the position or opinion of BfdW or the European Union.

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