A plain-English explainer from the Repricing Carbon series. New here? Start with What Is a Carbon Credit?
When I started learning this market, the concepts were not the hard part. The hard part was the cast of characters. Every article assumed I already knew who Verra was, what ICVCM stood for, which newsletter everyone reads, and where everyone goes in September. I did not. So I built myself a map as I went, and this is that map, cleaned up. If you are newer to this than me, I hope it saves you the confusion I waded through. If you know it better than me, I would genuinely welcome the corrections.
Here is the one idea that made all of it click. The carbon market has a supply side and a demand side, with a layer of referees and reporters in between. Credits are created on the supply side, bought on the demand side, and judged by everyone in the middle. Once you sort each name into one of those buckets, the whole thing stops feeling like alphabet soup.
Supply side
Registries create the credits. Project developers build the projects behind them.
The middle
Rating agencies grade the credits. Integrity bodies set the rules. The press reports it all.
Demand side
Companies buy the credits, then make public claims about how they used them.
Every name below fits into one of these. That is the whole trick.
The registries: who creates the credits
A registry is the body that approves a project’s accounting method, issues its credits, and keeps the ledger of who owns what. They are the supply-side plumbing. These are the names you will see stamped on almost any credit.
Verra
The largest registry, home of the Verified Carbon Standard (VCS). If you only learn one registry name, learn this one.
Gold Standard
Founded by WWF and other NGOs, known for a strong focus on community and sustainable-development benefits alongside carbon.
ACR and Climate Action Reserve
Two long-running North American registries you will run into often, especially on US-based projects.
Puro.earth
A newer registry focused specifically on engineered carbon removals, like biochar and mineralization.
A thing I had to unlearn early: a registry’s stamp means a project followed an approved method. It does not promise the credit is good. That gap is the reason the next group exists. I wrote a whole short piece on it if you want it: what a carbon registry actually does.
The rating agencies: who grades the credits
This is the layer that barely existed five years ago. Rating agencies sit between the registry and the buyer and answer the question the registry does not: is this specific credit likely to be as good as it claims? Three names lead the field.
Calyx Global
US-based, buyer-funded, and known for keeping a credit’s climate score separate from its community-impact score. The firm I point readers to most often.
BeZero Carbon
UK-based, founded in 2020, with a widely used risk-rating framework and a large public rating coverage.
Sylvera
Also UK-based, known for detailed data tooling and deep analysis of forestry and nature-based projects.
Here is a detail I found genuinely encouraging as a learner. The three big agencies have largely converged on the same kind of letter scale, roughly AAA down to D, the same shape the bond market uses. And serious buyers increasingly refuse to purchase below a set rating. By some industry surveys, a large majority of corporate buyers now require a minimum grade before they will sign. High-rated credits have started selling at a real premium over low-rated ones in the same category. That is the market learning to pay for quality, in real time.
If you want the plain version of how a rating works and why “who pays the rater” is the whole question, I wrote that up here: what is a carbon credit rating?
The integrity bodies: who sets the rules
These are the referees. They do not issue credits or rate them. They write the standards that say what “good” means, and they split neatly along that supply-and-demand line. This was the group whose acronyms confused me the longest, so here they are in plain English.
ICVCM (supply side)
The Integrity Council for the Voluntary Carbon Market. It defines what a high-integrity credit looks like, through its Core Carbon Principles. Think of it as the quality seal on the supply.
VCMI (demand side)
The Voluntary Carbon Markets Integrity Initiative. It defines what a company is allowed to claim when it uses credits, through its Claims Code. It governs the story, not the credit.
SBTi (demand side)
The Science Based Targets initiative. It defines what counts as a credible corporate climate target, and how credits do or do not fit into one.
Oxford Principles
A widely cited academic framework for how credible offsetting should shift over time toward genuine carbon removal.
The clean way to hold it: ICVCM judges the credit, SBTi shapes your target, VCMI governs what you say out loud. Calyx has a helpful side-by-side on these if you want to go deeper, the difference between SBTi, VCMI, ICVCM and the Oxford Principles.
The press: how to actually keep up
This is the part nobody told me, and it is the fastest way to stop feeling lost. A few publications carry the real news, and following them taught me more than any single report.
Carbon Pulse
The market’s daily newspaper. Its free CP Daily newsletter rounds up the day’s carbon and climate stories. The single best starting subscription.
Quantum Commodity Intelligence
Strong on prices, data, and market analysis, with a dedicated voluntary-carbon focus.
Trellis
The sustainable-business publication formerly known as GreenBiz. Good for the corporate-buyer point of view.
Carbon Market Watch
A watchdog NGO, not a newswire. Worth following precisely because it pushes back and keeps the market honest.
The gatherings: where everyone shows up
The market runs partly on conferences. You do not need to attend them to follow along, but knowing the calendar helps you understand why news clusters around certain weeks. These are the ones I keep hearing about.
Climate Week NYC
Each September, alongside the UN General Assembly. The single biggest cluster of climate and carbon announcements all year.
London Climate Action Week
The early-summer European counterpart, with a heavy finance and policy presence.
North American Carbon World
A major North American carbon-market conference, held in San Diego in spring 2026. Practical, market-focused sessions.
Carbon Forward and Argus
Carbon Forward (London and other cities) and the Argus carbon conferences are go-to events for traders and analysts.
COP
The annual UN climate summit. Not carbon-specific, but the place where the biggest policy signals land.
Putting the map together
Here is the whole thing in one breath. Registries create credits. Rating agencies grade them. Integrity bodies set the rules, ICVCM for the credit, SBTi for the target, VCMI for the claim. The press reports what is happening, and the conferences are where it gets announced. Sort any new name you meet into one of those five boxes, and you will almost always know what it does.
That is the map I wish someone had handed me at the start. I am still filling it in, and I am sure I have a square or two in the wrong place. If you spot one, tell me, and we will both learn something.
Where to go next
If you want to see how these players actually interact as the market improves itself, that is the heart of the series finale, the reform loop. And if you would rather go back to the foundations, the whole guide starts at Repricing Carbon.
A note from the author. I have spent the better part of two decades working in sustainability: in solar and clean energy, in permaculture and regenerative land projects, and in marketing the mission-driven businesses trying to do this right. Carbon credits are the part of that world I came to most recently, and I am still very much a learner here. 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.