The carbon market has its own vocabulary, and much of the confusion in buying credits comes from terms that sound familiar but mean something specific. This glossary explains the 60 terms that come up most in quotes, contracts and claims, in one or two sentences each, with a link to the full guide where there is one.
A carbon credit represents one tonne of CO2 equivalent (tCO2e) avoided or removed by a project, certified by an independent standard and recorded in a public registry. The terms below explain what makes that tonne credible, how it is traded and what you may claim with it.
A-B
Additionality: The test that a project’s reduction or removal would not have happened without carbon finance. It is the first criterion in the ICVCM’s Core Carbon Principles. See additionality explained.
Afforestation, reforestation and revegetation (ARR): Projects that plant or regrow trees and vegetation to remove CO2. They are nature-based removals with decades-to-centuries storage.
Allowance (EUA): A permit to emit one tonne of CO2 equivalent under the EU ETS. An allowance is not a carbon credit and cannot be used to offset emissions.
Article 6: The part of the Paris Agreement that lets countries cooperate on emission reductions, including transfers between countries (6.2) and a UN crediting mechanism (6.4). See Article 6 explained.
Avoidance credit: A credit for emissions that were prevented, for example by protecting a forest or replacing wood fires with efficient stoves. It differs from a removal credit. See avoidance vs removal.
Baseline: The scenario of what emissions would have been without the project. A generous baseline produces more credits than real tonnes, which is the main cause of over-crediting.
BECCS: Bioenergy with carbon capture and storage: CO2 from burning or processing biomass is captured and stored underground. It is a long-lived removal.
Beneficiary: The company on whose behalf a credit is retired, named in the registry. Only the beneficiary can claim the tonne. See carbon credit registries.
Biochar: Stable carbon made by heating biomass without oxygen and mixing it into soil or materials. It is the most traded durable removal today. See the best biochar projects.
Blue carbon: Carbon stored by coastal ecosystems such as mangroves, seagrass and salt marshes, mostly in their waterlogged soils. See blue carbon credits.
Buffer pool: A shared reserve of credits that projects with reversal risk deposit into. When stored carbon is lost, buffer credits are cancelled to compensate. See permanence and buffer pools.
C
Carbon credit: A certificate representing one tonne of CO2 equivalent avoided or removed by a verified project, with a unique serial number in a registry. See what are carbon credits.
Carbon offset: The use of a carbon credit to compensate for a tonne of your own emissions, by retiring it. The words are often used interchangeably. See what is a carbon offset.
Carbon dioxide removal (CDR): Any activity that takes CO2 out of the atmosphere and stores it, from reforestation to direct air capture. See carbon dioxide removal explained.
Carbon neutral: A claim that the net emissions of a product or company are zero through reductions and offsets. Since 27 September 2026, EU consumer law bans offset-based carbon neutral claims on products, and company-wide claims are restricted as well. See the EmpCo carbon neutral claim ban.
CBAM: The EU’s Carbon Border Adjustment Mechanism, which charges importers for the embedded emissions of goods such as steel, aluminium and cement. Its definitive phase started in 2026. See EU ETS explained.
CCB Standards: Verra’s Climate, Community and Biodiversity Standards, which certify a project’s benefits beyond carbon. See co-benefits.
CCP label: A label that a registry applies to credits from a methodology approved by the ICVCM under an approved programme. See Core Carbon Principles.
Co-benefits: The effects of a project beyond carbon, such as jobs, health, water and biodiversity, often mapped to the UN Sustainable Development Goals.
Compliance market: A carbon market created by law, such as the EU ETS, where covered companies must surrender allowances for their emissions. See voluntary vs compliance markets.
Contribution claim: A claim that states which verified projects a company financed, without suggesting its own emissions are cancelled. It is the claim EU consumer law still allows. See contribution claims.
Core Carbon Principles (CCPs): Ten quality principles for carbon credits set by the ICVCM, covering governance, emissions impact and sustainable development.
CORSIA: The international aviation scheme under which airlines offset growth in international flight emissions, using only authorised credits in its first phase. See buying CORSIA credits.
Corresponding adjustment: An accounting step in which a host country removes an authorised, transferred tonne from its own emissions balance, so it is counted only once.
CRCF: The EU’s Carbon Removals and Carbon Farming Certification framework (Regulation (EU) 2024/3012), a government-backed certification for removals and carbon farming. See CRCF certified carbon credits.
D-H
Direct air capture with storage (DACCS): Machines that pull CO2 from the air for geological storage. It is the most measurable and most expensive removal.
Digital MRV (dMRV): The use of sensors, satellite data and automated data systems to measure and report a project’s results, allowing more frequent issuance. See MRV explained.
Double counting: When the same tonne is claimed by more than one party, for example a buyer and a host country. Serial numbers, retirement and corresponding adjustments prevent it.
Durability: How long removed carbon stays stored. SBTi distinguishes short-lived (decades to centuries) from long-lived (centuries to millennia) removals.
EmpCo: The EU Empowering Consumers Directive (2024/825). Since 27 September 2026 it bans claims towards consumers that a product is carbon neutral because of offsetting. See the EmpCo carbon neutral claim ban.
Enhanced rock weathering (ERW): Spreading crushed silicate rock on land so it reacts with CO2 and stores it as carbonate. Storage is long-lived; measurement is the main challenge. See the best ERW projects.
EU ETS: The EU Emissions Trading System, a cap-and-trade market for power, heavy industry, aviation in Europe and shipping. See EU ETS explained.
Ex-ante and ex-post credits: Ex-post credits are issued after the tonne has been verified; ex-ante (forward) units are issued for expected future results. SBTi V2.0 only counts verified ex-post removals.
I-M
ICVCM: The Integrity Council for the Voluntary Carbon Market, which sets the Core Carbon Principles and approves programmes and methodologies against them.
Insetting: Financing reductions or removals inside your own value chain, which can lower your Scope 3 emissions if traceable. See insetting vs offsetting.
Internal carbon price: A price per tonne a company uses internally, as a shadow price for decisions or as a fee that funds reductions and credits. See internal carbon pricing.
ITMO: An internationally transferred mitigation outcome: a tonne authorised by a host country and transferred under Article 6.2.
Leakage: Emissions that move elsewhere because of a project, for example logging that shifts to a nearby forest. Methodologies deduct for expected leakage.
Methodology: The rulebook a project type follows to calculate its tonnes, set its baseline and prove additionality, approved by a standard.
MRV: Measurement, reporting and verification: how a project measures its results, reports them and has them verified before credits are issued.
N-R
Nature-based solutions: Projects that protect, restore or manage ecosystems, such as forests, soils and mangroves. See nature-based vs technology-based credits.
Net zero: The state in which a company has cut its emissions in line with science and neutralises the residual emissions with removals. See the difference between carbon neutral and net zero.
Offtake agreement: A multi-year contract to buy a share of a project’s future credits, often at a fixed price. See carbon offtake agreements.
Over-crediting: Issuing more credits than the real tonnes a project avoided or removed, usually because of a generous baseline.
Paris Agreement Crediting Mechanism (PACM): The UN-supervised crediting mechanism under Article 6.4, successor to the Clean Development Mechanism.
Permanence: How long the carbon behind a credit stays out of the atmosphere, and how the risk of losing it is covered.
REDD+: Projects that reduce emissions from deforestation and forest degradation by protecting forests. See the best REDD+ credits.
Registry: The public database of a standard that records every credit, its holder and whether it has been retired. See carbon credit registries.
Removal credit: A credit for CO2 taken out of the atmosphere and stored, for example by reforestation, biochar or direct air capture. Under SBTi, only removals can neutralise residual emissions at net zero.
Retirement: The registry action that permanently takes a credit out of circulation for a named beneficiary. Only retired credits can back a claim.
Reversal: The release of stored carbon back into the atmosphere, for example through a forest fire. Buffer pools or insurance cover reversals.
S-V
SBTi: The Science Based Targets initiative, whose Corporate Net-Zero Standard V2.0 sets how companies set targets and, from 2035, requires larger companies to support carbon removals. See SBTi carbon removal requirements.
Scope 1, 2 and 3: The three categories of a company’s emissions: direct (1), purchased energy (2) and the rest of the value chain (3). Credits never reduce them. See scope 1, 2 and 3 explained.
Serial number: The unique identifier of each credit in a registry, which prevents the same tonne from being sold twice.
Spot, forward and offtake: Ways to buy credits: issued credits delivered now (spot), a fixed price for a future delivery (forward), or a multi-year share of a project’s output (offtake). See spot vs forward vs offtake.
VCMI: The Voluntary Carbon Markets Integrity Initiative, whose Claims Code sets rules for credible claims about credit use. See VCMI Claims Code.
Verra (VCS): The largest carbon crediting standard, which runs the Verified Carbon Standard and its registry. See the best Verra VCS projects.
Vintage: The year in which the reduction or removal behind a credit took place. Recent vintages generally trade at a premium. See carbon credit vintage.
Voluntary carbon market (VCM): The market where companies buy carbon credits without a legal obligation. See voluntary carbon market explained.
Validation and verification body (VVB): An accredited auditor that checks a project’s design (validation) and results (verification) before credits are issued.
Tip from Bernard de Wit, Founder of Regreener: “If a quote uses a term from this list without explaining it, ask. ‘Premium’, ‘high-integrity’ and ‘certified’ mean nothing on their own. Additionality, baseline, permanence and retirement in your name are the words that tell you what you are actually buying.”
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Send us the quote and we will translate it into these terms: project, methodology, vintage, quality and what you can claim.
