A plain-English explainer from the Repricing Carbon series. New here? Start with What Is a Carbon Credit?
Early on, I kept reading the phrase “carbon market” and quietly assuming it meant one thing. It does not. There are two very different carbon markets, they work in almost opposite ways, and mixing them up is one of the most common beginner mistakes. Here is the difference, cleanly.
Compliance market
A government tells certain companies they must cut emissions. To stay under a legal cap, they trade official allowances. Participation is mandatory. Break the rules and you pay a penalty.
Voluntary market
A company chooses, on its own, to buy carbon credits to support climate action beyond what any law requires. Nobody forces it. The credits come from projects, not government allowances.
The compliance market, in plain terms
A compliance market works on a “cap and trade” idea. The government sets a ceiling on total emissions for an industry, hands out or auctions a limited number of allowances, and lowers the ceiling over time. A company that pollutes less than its share can sell its leftover allowances. A company that pollutes more has to buy extra. The shrinking cap is what slowly forces emissions down.
These are the big regulated systems you will hear named:
The voluntary market, in plain terms
The voluntary market is the one this whole series is about. No law requires a company to participate. A business decides, for its own reasons, brand, values, customer pressure, future regulation, that it wants to fund climate action. It buys carbon credits from projects that protect forests, capture carbon, or replace dirty technology. The credit is a claim that one ton of carbon was avoided or removed somewhere in the world.
Compliance is “you must.” Voluntary is “we choose to.” When someone says “carbon credit” in a sustainability context, they almost always mean the voluntary kind.
One number that surprised me
The two markets are wildly different in size. The compliance markets move enormous sums, the EU system alone has traded in the hundreds of billions of euros. The entire voluntary market, by contrast, has been valued at only a couple of billion dollars. The voluntary market is the small, scrappy, fast-changing one. That is part of why its quality problems got so much attention, and why the trust-building work this series describes matters so much.
Why a buyer should care which is which
If you are a company choosing to support climate action, you are almost certainly in the voluntary market, and the skills this series teaches apply directly: judging credit quality, leaning on independent ratings, making defensible claims. If you are a regulated emitter in California or Europe, you are also dealing with a compliance system, which runs on government allowances and its own rules. Knowing which conversation you are in is the first step to not getting lost.
Where to go next
That is the fork in the road. This series lives in the voluntary market, where the choices are yours and the quality is yours to check. To see why that quality became such a big deal, start with Part 1 of the series. Or go back to the foundation with what a carbon credit is.
A note from the author. I am a writer who cares about sustainability, and when it comes to carbon credits I am still very much a learner. There are a lot of people who know this market far better than I do, and I have real respect for the work they have put into building it. If I got something wrong in here, I apologize, and I would genuinely like to hear about it so I can learn and correct it. I am writing this to start a conversation, not to have the last word. That is the whole point. This is a learning experience for me too, and the conversation is what moves all of us forward. If this piece helped you, share it. If you see it differently, even better. Let’s talk.