Tokenisation has occupied an outsized share of carbon-market discourse since 2021. Some of that energy produced durable engineering progress; much of it conflated ledger structure with environmental integrity. CAS's view, formed across registry implementations and post-mortems of the 2022 BCT/NCT spike, is that on-chain layers solve a narrow but real set of problems — and cannot solve the upstream integrity problems that dominate carbon markets.
What tokenisation actually solves
Cross-registry reconciliation. A tokenised wrapper provides a single canonical reference that can sit alongside Verra, Gold Standard, ACR, ART TREES, and Puro records. This is genuinely useful for buyers consolidating exposure across registries.
Programmable retirement. Smart-contract retirement enables conditional logic — retire-on-claim, basket-level redemption, automated beneficiary assignment — that registry UIs do not natively support. Toucan's TCO2 and retirement-certificate contracts implement this pattern, with retirements synced back to the underlying Verra or Puro registry [1][2].
Disclosure-grade auditability. A public ledger of issuance, transfer, and retirement events is structurally suited to corporate climate-disclosure use cases under CSRD and CDP, where buyers need a verifiable chain back to the source serial number.
What tokenisation does not solve
Integrity at the project level. The hardest problems in carbon — additionality, permanence, leakage, social safeguards — sit upstream of any registry, on-chain or off. The Verra-Toucan bridging restrictions imposed in May 2022 (banning the bridging of pre-2016 vintage REDD+ credits) were a response to the on-chain market revealing — not creating — weak underlying data.
Custody and rights are also harder than they look on a tokenised surface. Holding a TCO2 token does not automatically grant the same legal rights to a retirement claim that holding a registry account balance does; legal terms vary by jurisdiction, by registry, and by bridge operator [3].
What modern registries should learn
The useful engineering lessons from the tokenisation experiment are portable to off-chain registries: cryptographically signed retirement records; serial-number schemes designed for cross-registry resolution; machine-readable methodology and vintage metadata; and public, API-first issuance and retirement event streams. Verra's transition to a next-generation registry in partnership with S&P Global Commodity Insights, announced August 2025, is partially shaped by these expectations [4].
Where CAS fits in
CAS designs registries that work for sovereign and program operators regardless of whether an on-chain layer is bolted on later. Our work focuses on: (a) data models that separate issuance, holding, and retirement as distinct objects; (b) serial-number schemes designed for cross-registry resolution; (c) cryptographic audit trails for retirement events; and (d) public APIs that enable downstream tokenisation, disclosure, or analytics without re-engineering the core. We take no position on whether a given registry should expose a tokenised wrapper.
Sources
[1] Toucan Protocol Documentation, 'Carbon Retirements'.
[2] Toucan Protocol Documentation, 'Retirement Certificates'.
[3] CarbonMeld, 'Comparing ReFi Protocols for Tokenizing Carbon Credits'.
[4] Verra, 'Transition to Verra's New Registry'.