What Is a Carbon Credit?
A carbon credit is a certificate representing the reduction or removal of one metric tonne of carbon dioxide equivalent from the atmosphere. When a project prevents emissions โ say, by replacing a coal plant with a wind farm โ it can generate credits equal to the tonnes avoided. When a project actively pulls CO2 out of the air, such as reforestation, it generates removal credits. Either way, one credit equals one tonne.
Compliance vs. Voluntary Markets
There are two main markets for carbon credits. Compliance markets are created by governments that require certain industries to limit their emissions. Companies in these systems must hold enough permits or credits to cover what they emit, and they can trade with each other. The European Union Emissions Trading System is the largest example. Voluntary markets, by contrast, exist because companies, organizations, and individuals choose to buy credits on their own, usually to meet sustainability goals or to offset emissions from products, services, travel, or operations.
How Credits Are Verified
Credibility depends on verification. Independent standards organizations like Gold Standard and Verra review offset projects, confirm that emission reductions are real and measurable, and issue credits only after rigorous auditing. These standards check that the reductions would not have happened without the project โ a concept called additionality.
Scale and Access
The voluntary carbon market has grown from a niche activity into a multi-billion-dollar system. Companies purchase credits in bulk to meet net-zero commitments, while smaller businesses and individuals can buy smaller quantities through online platforms. As the market matures, transparency around project quality and pricing continues to improve, though buyers still need to evaluate what they are purchasing carefully.