What carbon credits are, how one credit equals one tonne of CO₂e, how they are generated, verified and retired, and the difference between voluntary and compliance markets.
Introduction
Carbon credits are one of the most talked-about — and most misunderstood — tools in climate action. Done well, they channel billions into forest protection, clean cooking and carbon removal. Done badly, they become greenwashing. Understanding what a carbon credit actually is is the first step to using them credibly. This guide explains the fundamentals; the rest of our carbon-credits series goes deeper on buying and claiming, quality, and the GCC market.
What a carbon credit is
A carbon credit represents one tonne of carbon dioxide equivalent (CO₂e) that has been reduced, avoided or removed from the atmosphere. Each credit is uniquely serial-numbered on a registry, so it can be tracked and used only once. When a company uses a credit to compensate for its emissions, it retires the credit — permanently removing it from circulation so no one else can claim it.
How credits are generated
Credits do not appear from nowhere. A project — reforestation, methane capture, a renewable-energy plant — must follow a rigorous cycle:
| Step | What happens |
|---|---|
| Methodology | The project applies an approved crediting methodology |
| Validation | An independent auditor (VVB) confirms the design and additionality |
| Registration | The project is listed on a registry |
| Verification | Actual reductions are measured and independently verified |
| Issuance | Serial-numbered credits are issued |
| Retirement | A buyer retires the credit to claim the benefit |
We cover this in detail in how to register a carbon project.
Two markets: voluntary and compliance
| Voluntary (VCM) | Compliance | |
|---|---|---|
| Driver | Company choice / climate commitments | Government regulation |
| Unit | Carbon credit | Allowance / compliance unit |
| Rules | Independent standards (Verra, Gold Standard) | Law (e.g. emissions trading systems) |
| Example | Buying credits for a net-zero claim | Surrendering allowances under a cap |
Article 6 of the Paris Agreement is increasingly bridging the two, allowing countries to trade mitigation internationally.
A carbon credit is a promise made physical: one tonne of CO₂ kept out of the atmosphere, measured, verified, and tracked so it can only be claimed once.
Quality is everything
Not all credits are equal. A credit is only as good as the project behind it — and whether that project’s reductions are real, additional, permanent and not double-counted. After years of quality controversy, the market now has integrity benchmarks: the ICVCM Core Carbon Principles for the credits themselves and the VCMI Claims Code for the claims companies make. We unpack both in carbon credit quality & integrity.
How ESGweise helps
ESGweise helps GCC companies use carbon credits credibly — building a decarbonisation-first strategy, sourcing high-integrity credits, and making defensible claims aligned with the ICVCM and VCMI. See our carbon and strategy practices and our guide to carbon-neutral certification.
References & sources
- Verra — Verified Carbon Standard
- Gold Standard
- ICVCM — Core Carbon Principles
- VCMI — Claims Code of Practice
- UNFCCC — Article 6 (cooperative implementation)
Conclusion
A carbon credit is a simple idea with demanding execution: one verified tonne of CO₂e, tracked on a registry, retired when claimed. There are two markets — voluntary and compliance — and quality ranges from excellent to worthless. Used after genuine decarbonisation, with high-integrity credits and honest claims, carbon credits are a legitimate climate tool. Used as a substitute for cutting emissions, they are greenwashing. The difference is in the detail — which the rest of this series explains.
Frequently asked questions
What is a carbon credit?
A carbon credit is a tradable certificate representing one tonne of carbon dioxide equivalent (CO₂e) that has been reduced, avoided or removed from the atmosphere by a project. Each credit is uniquely serial-numbered on a registry so it can be tracked and can only be used once. Companies buy credits to compensate for emissions they cannot yet eliminate, and 'retire' the credit to claim its climate benefit.
How is a carbon credit different from a carbon offset?
The terms are often used interchangeably, but there is a nuance. A carbon credit is the unit — one tonne of CO₂e on a registry. 'Offsetting' is the act of using (retiring) a credit to compensate for your own emissions. So you buy carbon credits and use them to offset. All offsets are credits being retired; not all credits are used for offsetting (some are cancelled or held).
What is the difference between the voluntary and compliance carbon markets?
The compliance market is created by regulation — governments cap emissions and issue allowances that regulated entities must surrender (for example, an emissions trading system). The voluntary carbon market (VCM) is where companies and individuals buy credits by choice, to meet their own climate commitments rather than a legal obligation. The two markets have different units, prices and rules, though Article 6 of the Paris Agreement is increasingly connecting them.
Are carbon credits worth buying?
High-integrity credits can channel real finance to genuine climate projects and are a legitimate part of a credible net-zero strategy — after a company has cut its own emissions first. But quality varies enormously, and low-quality credits have driven greenwashing controversies. The value depends on buying credits that meet integrity standards like the ICVCM Core Carbon Principles and making honest claims about them under guidance such as the VCMI Claims Code.