Characteristic of a change which would not have occurred without the linked policy intervention or activity (IPCC AR6 WGIII). Since additionality is impossible to demonstrate with 100% certainty, it is more accurate to refer to and estimate the “risk of non-additionality”. International efforts such as the Integrity Council for the Voluntary Carbon Market (ICVCM) are adopting this approach. Note that additionality is a strict requirement of compensation claims (e.g., use of carbon removal for offsetting), but can be relaxed or even ignored when there is no compensation claim being made (e.g., direct government payments to farmers to incentivise a shift to regenerative practices). Three primary tests for assessing the risk of non-additionality are typically used:
  • Financial additionality – Are the revenues from the carbon project the decisive factor in allowing the project to proceed?
  • Regulatory surplus – To what degree is the activity already incentivised or required under the existing policy regime?
  • Common practice – Is the activity being financed commonly conducted? E.g., as more farmers in a region adopt regenerative agricultural methods, the risk of non-additionality increases as the activity becomes more widely understood and accepted.


Bioenergy with carbon capture and storage (BECCS) refers to the application of CCS technology to a bioenergy facility. Depending on the total emissions of the BECCS supply chain, carbon dioxide can be removed from the atmosphere (IPCC AR6 WGIII).


Biomass carbon removal and storage (BiCRS) uses biomass to remove carbon dioxide from the atmosphere and store it underground, or in long-live products (Sandalow et al., 2021).

Carbon credit

A unit representing a one tonne of CO2 climate benefit. Carbon credits can either be an avoided emission / emission reduction carbon credit, or a removal carbon credit. If “offsetting” is the verb (the act of compensating for emissions), “carbon credit” is the noun (the unit of account). Carbon credits can be used in other contexts that are not offsetting.

Carbon offsetting

The act of compensating for a unit of carbon emissions with the purchase and retirement of a carbon credit.

Carbon pool

A reservoir in the Earth System allowing for carbon to remain over various periods of time, depending on the specific pool (IPCC AR6 WGIII).

Carbon removal

Anthropogenic activities removing CO2 from the atmosphere and durably storing it in geological, terrestrial, or ocean reservoirs, or in products (IPCC WGIII AR6). Carbon removal involves several modules: extraction from the air or upper ocean, conversion into a storable format, transportation, and storage. Carbon dioxide removal is often abbreviated “CDR”. Note that some policy environments (e.g., UK) use “greenhouse gas removal” as a broader category which contemplates the removal of GHGs other than CO2. “Carbon removal” could be interpreted to mean the removal of any GHG containing carbon (i.e., both CO2 and CH4 (methane)), but would not include the removal of other GHGs such as N2O.

Carbon sink

A carbon sink is anything, natural or otherwise, that absorbs more carbon from the atmosphere than it releases – for example, plants, the ocean and soil. In contrast, a carbon source is anything that releases more carbon into the atmosphere than it absorbs – for example, the burning of fossil fuels or volcanic eruptions.


Carbon capture and storage (CCS) is the separation of CO2 from industrial exhausts coupled with the permanent geological storage of that carbon (applied, e.g., on cement, steel, power plants, chemical production facilities, etc.). When the origin of the CO2 is exclusively fossil or geological carbon (e.g., fossil fuels, limestone), then this action is emission reduction, not carbon removal. Carbon dioxide removal and CCS are distinct, but some carbon dioxide removal methods (e.g., direct air capture) may share the same capture processes or long-term storage infrastructure used for conventional CCS.


Carbon capture and utilisation (CCU) is part of a broader set of ‘carbon recycling’ applications, describing the reuse of captured carbon either directly (e.g., to fertilise greenhouses, in beverages) or as an ingredient in new products (e.g., concrete, fuels, chemicals). CCU can displace additional fossil fuel use, thereby reducing emissions. If the carbon is removed from the atmosphere and stays in a closed loop over many decades or centuries (e.g. when incorporated into cementitious building materials), the method may be considered removal. All other cases of CCU, in which carbon is rapidly (re-)released to the atmosphere, only delay (re-)emissions. As most captured carbon is not durably stored, CCU is generally not considered removal.


Carbon dioxide removal, see carbon removal.

Climate benefit

An impact on climate and warming, for example the change in radiative forcing due to the removal of 1 tonne of CO2 from the atmosphere coupled with very long-lived storage of that carbon. Some climate benefits carry a higher degree of uncertainty than others.

Climate claims

An assertion by an entity (government, non-state actor such as a corporation, individual, etc.) that they have generated a positive climate outcome.
  • Compensation claim – An entity claims to have “compensated” for a negative impact by funding an equal and opposite positive impact. Carbon offsetting is the most common form of compensation claim, in which emissions are claimed to have been neutralised by the purchase and retirement of a carbon credit.
  • Contribution claim – An entity claims to have “contributed” to a positive climate outcome, perhaps through voluntary commitment of funds, without also taking credit for the climate outcome they are delivering. Examples could include: 1) direct government subsidy of a carbon removal project in which the climate benefit stays with and can be monetised by the project developer, 2) direct results-based funding of ecosystem restoration by a company, without that company receiving a carbon credit in return.

Climate neutrality

State in which all climate impacts are fully balanced with corresponding compensatory actions, such as removal of carbon or other remediation. Climate neutrality includes all greenhouse gases (e.g., CO2, CH4, N2O, etc.) and other climate impacts (e.g., albedo from land-use change, desertification, etc.).

Climate outcome

See climate benefit

Conventional removals on land

Methods that both capture and store carbon in the land reservoir. They are well-established practices already deployed at scale (TRL 8–9) and widely reported by countries as part of their LULUCF activities. Methods included are: afforestation/reforestation; soil carbon in croplands and grasslands; peatland and wetland restoration; agroforestry; improved forest management; and durable Harvested Wood Products. The latter is included as it is already deployed at scale and the carbon remains as biomass (Smith et. al, 2023).


Direct air carbon capture and storage is a chemical process by which CO2 is captured directly from the ambient air, with subsequent storage. Also known as direct air capture and storage (DACS) (IPCC AR6 WGIII).


A physical characteristic of stored carbon reflecting its risk of reversal back into the atmosphere. Durability is a spectrum (lower vs. higher durability) rather than a binary distinction.

Greenhouse gas

Greenhouse gases (GHG) are those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit radiation at specific wavelengths within the spectrum of terrestrial radiation emitted by the earth's surface, the atmosphere itself, and by clouds. This property causes the greenhouse effect. Water vapour (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) and ozone (O3) are the primary GHGs in the earth's atmosphere. Moreover, there are a number of entirely human-made GHGs in the atmosphere, such as the halocarbons and other chlorine- and bromine-containing substances, dealt with under the Montreal Protocol. Beside CO2, N2O and CH4, the Kyoto Protocol deals with the GHGs sulphur hexafluoride (SF6), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) (IPCC AR6 WGIII).

Greenhouse gas removals

See carbon removal

Important Projects of Common European Interest

Important Projects of Common European Interest (IPCEI) are strategic instruments for the implementation of the European Union (EU) Industrial Strategy.  

Indirect Carbon Leakage

The displacement of GHG emissions to another location due to actions in one location, thereby counteracting some or all of the desired mitigation effects (IPCC AR6 WGIII). For example, reforesting sheep pasture land in one country may lead to additional land clearing to make room for additional sheep pasture in another country to meet constant demand. Frameworks like the Carbon Opportunity Cost allow for analysis to estimate the magnitude of this displacement, which is a function of the efficiency of production at the location to which the activity is displaced.


The InvestEU Programme supports sustainable investment, innovation and job creation in Europe. It aims to trigger more than €372 billion in additional investment over the period 2021-27.


Intergovernmental Panel on Climate Change


Lifecycle assessment (LCA) is a compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product or service throughout its life cycle (IPCC AR6 WGIII).


See indirect carbon leakage 


Land use, land use change and forestry is a "a GHG inventory sector that covers anthropogenic emissions and removals of GHG from carbon pools in managed lands, excluding non-CO2 agricultural emissions", within a context of GHG inventories under the UNFCCC (IPCC WGIII AR6).

CDR method

A carbon removal method is a technique for removing, converting & transporting (if necessary), and storing carbon. Examples include “forestation” and “direct air capture with carbon storage”.


The corresponding process description for each carbon removal method, with associated documentation allowing for the evaluation, measurement, and potential certification of an instance of carbon removal. Methodologies could describe a discrete module of a carbon removal method, such as a particular technique for extraction (sorbent-based direct air capture), or a particular type of storage (injection into a saline aquifer), rather than a full-chain method.


Measurement, reporting and verification (MRV)
  • Measurement - is the process of collecting data over time, providing basic datasets, including associated accuracy and precision, for the range of relevant variables (UN REDD, 2009).
  • Reporting - following predetermined formats and established standards (e.g. the IPCC) it refers to the process of formal reporting of assessment results to the UNFCCC (UN REDD, 2009), or any other relevant third party or authority.
  • Verification - according to established approaches, it refers to the formal verification process of reports (UN REDD, 2009).

Net negative

A state in which anthropogenic GHG removals exceed anthropogenic GHG emissions for a defined region or entity and over a set time period (IPCC AR6 WGIII).

Net zero

State in which emissions of GHGs are in balance with removals of that same GHG for a defined region or entity and over a set time period (IPCC AR6 WGIII).


National inventory reporting


Non-fungibility principle refers to CDR methods or to carbon sinks considered as distinct and not interchangeable. For example, "land sinks and geological storage should be considered as non-fungible".

Novel removals

All other methods storing captured carbon in the lithosphere (geological formations), ocean or products, not included as conventional removal methods. Generally at a TRL below 8–9, they are currently deployed at smaller scales, e.g. BECCS, direct air carbon capture and storage (DACCS), biochar and ocean alkalinisation (Smith et. al, 2023).


A hypothetical ideal state in which stored carbon persists in perpetuity. Absolute permanence is not attainable, but real-world residence times of carbon in soils, forests, geology, and products can be compared against the ideal of permanence. A distinction can be drawn between physical permanence (as defined above) and contractual permanence, which is the use of legal and financial contracts to simulate permanence by holding someone responsible for remediation in the event of a reversal. Permanence is sometimes used to mean “residence time”, or the actual duration in years that a GHG is expected to remain out of the atmosphere.

Recovery and Resilience Facility

The RRF was conceived to mitigate the impacts of the pandemic and support Europe through the green and digital transitions. The Facility is a temporary recovery instrument. It allows the Commission to raise funds to help Member States implement reforms and investments that are in line with the EU’s priorities and that address the challenges identified in country-specific recommendations under the European Semester framework of economic and social policy coordination. It makes available €723.8 billion (in current prices) in loans (€385.8 billion) and grants (€338 billion) for that purpose The RRF helps the EU achieve its target of climate neutrality by 2050 and aims to set Europe on a path of digital transition, creating jobs and spurring growth in the process.

Residual emissions

Residual emissions means [a party’s] GHG Emissions [from all operations including its value chain] that are emitted after all reasonable efforts have been made to reduce them.  


A reversal occurs when stored carbon escapes and is released back into the atmosphere, reducing or nullifying the climate benefit that has been delivered by the initial instance of removal. Reversals can be non-anthropogenic (“acts of God”, natural disasters such as wildfires) or anthropogenic (caused by human misconduct or negligence, such as illegal logging). The “reversal risk” is an estimate of the expected magnitude and timing of reversals. Note that climate change itself is changing the risk of non-anthropogenic reversals in some cases, e.g., elevated frequency or severity of forest fires or extreme weather events may increase reversal risk in some regions. See also “durability” and “permanence”.

Stewardship principle

An underlying principle of carbon removal in which stored carbon is at all times the responsibility of an assigned steward. The steward might initially be the entity responsible for storing the removed carbon (e.g., a North Sea geological storage operator under the CCS Directive), with stewardship being reassigned at a later date subject to some statute of limitations (e.g., stewardship automatically transferred to a government body after X years). In the event of a reversal, the current steward is responsible for remediating the environmental impact, perhaps by paying for the removal and storage of an equivalent amount of carbon.


Technology readiness level, which according to the International Energy Agency follows a 1-11 scale defined as:
  • 1 - Initial idea (basic principles have been defined)
  • 2 - Application formulated (concept and application of solution have been formulated)
  • 3 - Concept needs validation (solution needs to be prototyped and applied)
  • 4 - Early prototype (prototype proven in test conditions)
  • 5 - Large prototype (components proven in conditions to be deployed)
  • 6 - Full prototype at scale (prototype proven at scale in conditions to be deployed)
  • 7 - Pre-commercial demonstration (prototype working in expected conditions)
  • 8 - First of a kind commercial (commercial demonstration, full-scale deployment in final conditions)
  • 9 - Commercial operation in relevant environment (solution is commercially available, needs evolutionary improvement to stay competitive)
  • 10 - Integration needed at scale (solution is commercial and competitive but needs further integration efforts)
  • 11 - Proof of stability reached (predictable growth)


Volatile organic compound