Dictionary

An emissions trajectory designed to limit warming to around 1.5°C, with no or limited overshoot, by rapidly reducing greenhouse-gas emissions and reaching net zero carbon dioxide globally.

24/7 carbon-free energy is an approach that seeks to match electricity consumption with carbon-free electricity supply on an hourly or similarly granular basis.

The reduction or avoidance of emissions of greenhouse gases or other pollutants, widely used in climate policy as a synonym for mitigation, though without a single agreed definition.

The cost of reducing one unit of emissions, usually expressed per tonne of CO₂-equivalent; ranking measures by this cost produces a marginal abatement cost curve.

Travel by physically active means — chiefly walking and cycling — undertaken in place of motorised trips, delivering public health benefits while cutting transport emissions.

The difference between what is needed for adequate climate adaptation — in finance, planning and implementation — and what is actually being provided or done.

The ability of systems, institutions, humans and other organisms to adjust to potential damage from climate change, take advantage of opportunities, or respond to consequences.

Additionality is the test of whether an emissions reduction or removal would not have occurred without the carbon finance, intervention or incentive being claimed.

Additionality in energy describes whether a purchase, project or intervention causes renewable or low-carbon energy generation beyond what would otherwise have occurred.

Afforestation is the establishment of forest on land that has not recently been forested, subject to the definition and time period used by the relevant framework.

Afforestation, reforestation and revegetation are land-based activities that establish or restore vegetation cover and may generate climate claims when measured against defined rules.

Greenhouse gas emissions from crop production and livestock — dominated by methane and nitrous oxide rather than CO₂ — making agriculture a distinct mitigation challenge.

A measure of how much sunlight a surface reflects back into space; declines in Earth's albedo — from melting ice to changing clouds — amplify warming through a self-reinforcing feedback loop.

The most established and widely deployed technology for producing hydrogen by splitting water with electricity, using an aqueous alkaline electrolyte.

The shortfall between the emissions cuts countries have pledged and the reductions needed to meet the Paris Agreement's temperature goals.

A US-based non-profit carbon crediting programme, founded in 1996 as the world's first private voluntary greenhouse gas registry, operating in both voluntary and compliance markets.

A nitrogen-hydrogen compound essential to fertiliser production — currently made mainly from fossil fuels with significant emissions — and a candidate low-emission fuel and hydrogen carrier.

An emerging electrolyser technology that combines features of alkaline and PEM systems, aiming for low-cost, flexible green hydrogen production without precious-metal catalysts.

An IEA World Energy Outlook scenario that assumes all government climate pledges — including net zero targets — are implemented in full and on time.

Annual matching is the matching of electricity consumption and energy attributes over a year, even when timing and location may differ.

Article 6 of the Paris Agreement is the part of the agreement that provides for cooperative approaches, including international transfer of mitigation outcomes and mechanisms.

The amount of a gas present in the atmosphere, expressed for CO₂ in parts per million — the direct measure of humanity's cumulative impact on the atmosphere's composition.

A competitive procurement mechanism in which governments or buyers solicit bids — used in sustainability chiefly for renewable energy support and carbon allowance allocation.

Australia's national carbon credit unit — one ACCU per tonne of CO₂-equivalent avoided or removed — issued under the ACCU Scheme and tradable in voluntary and compliance markets.

A carbon credit for emissions prevented relative to a baseline, as opposed to removed from the atmosphere — a distinction central to credible net-zero claims.

Preventing forest loss that would otherwise have occurred, generating emission reductions measurable against a reference level — the core logic of REDD+ and many forest carbon credits.

Avoided emissions are estimated emissions reductions outside an organisation’s own inventory that occur because a product, service or intervention displaces a higher-emitting alternative.

The GHG Protocol practice of restating base year emissions when structural or methodological changes break comparability, governed by a disclosed recalculation policy and significance threshold.

A baseline scenario is the reference case against which emissions reductions, removals, impacts or changes are estimated.

The reference year against which emissions performance, reductions or target progress are measured.

Baseload is the minimum level of electricity demand or supply that is present over a sustained period.

A vehicle powered solely by an electric motor drawing on a rechargeable battery — the dominant category within electric vehicles and a cornerstone of road-transport decarbonisation.

A battery energy storage system is a system that stores electrical energy in batteries and releases it when needed.

The electronic control system that monitors and protects rechargeable battery packs — managing voltage, current, temperature and cell balance to keep batteries safe, efficient and long-lived.

Storing electricity in rechargeable batteries — from home systems to grid-scale plants — the fastest-growing energy technology of 2023 and a cornerstone of integrating variable renewables.

Energy systems installed on the customer's side of the utility meter — rooftop solar, batteries, efficiency — that serve the site first rather than feeding the wider grid.

The emissions per unit of output achieved by the most efficient producers in a sector, used as the benchmark against which others' decarbonisation is measured and rewarded.

Beyond value chain mitigation is climate action or finance outside an organisation's own value chain, intended to support wider mitigation while not replacing internal emissions reductions.

A World Bank carbon fund, operational from 2004, that pioneered payments for emission reductions from land use — forests, agriculture and land restoration — continuing today through the ISFL.

Biochar is a carbon-rich material made by heating biomass in limited oxygen and used in some contexts as a carbon removal or soil amendment pathway.

Energy derived from biomass — the largest single source of renewable energy today, spanning traditional firewood to modern biofuels, biogas and BECCS.

Burning or converting biomass for energy while capturing and geologically storing the CO₂ — one of the few technologies that generates energy while removing carbon from the atmosphere.

Biofuel is fuel produced from biological material such as crops, residues, waste oils, wood or other biomass.

A methane-rich gas produced when organic matter decomposes without oxygen — captured from digesters, landfills and wastewater plants for heat, power and cooking.

CO₂ released from burning or decomposing biomass — carbon recently absorbed from the atmosphere — which GHG accounting requires to be reported separately from fossil emissions.

Near-pure methane produced by upgrading biogas or gasifying biomass — chemically indistinguishable from natural gas and usable in existing gas grids and vehicles.

The light-absorbing particulate component of soot from incomplete combustion — a short-lived climate pollutant ranked second only to CO₂ as a cause of human-driven warming.

Blue carbon is carbon stored or sequestered in coastal and marine ecosystems such as mangroves, tidal marshes and seagrasses.

Blue hydrogen is hydrogen produced from fossil fuels with carbon capture and storage applied to some associated emissions.

A buffer pool is a reserve of credits or units set aside to manage reversal, non-permanence or other integrity risks in a crediting system.

Cap and trade is a policy design that limits total permitted emissions and allows covered entities to trade emission allowances within that cap.

The ratio of a power plant's actual energy output over a period to its maximum possible output at rated capacity — the key metric for comparing generation technologies.

The systematic measurement of an organisation's greenhouse-gas emissions across Scopes 1, 2 and 3 — the measurement layer on which targets, disclosure and carbon markets all depend.

The maximum cumulative net carbon dioxide emissions consistent with limiting warming to a specified level with a stated likelihood and set of assumptions.

A process that captures carbon dioxide from industrial or energy sources, transports it and stores it in geological formations to prevent atmospheric release.

An umbrella term for capturing carbon dioxide and either using it in products or processes or storing it in geological formations.

A carbon credit is a transferable unit that represents a quantified emissions reduction or removal issued under a defined programme, methodology and accounting system.

The continuous movement of carbon among the atmosphere, oceans, soils, living things and rocks — the natural system that human emissions have pushed out of balance.

The primary long-lived greenhouse gas emitted by human activity — the reference unit (CO₂e) for all climate accounting and the central variable of climate policy.

A common unit that converts the climate effect of different greenhouse gases into the amount of carbon dioxide with an equivalent warming effect over a stated time horizon.

Carbon farming is the use of land management practices intended to reduce emissions or increase carbon storage in soils, vegetation or agricultural systems.

The quantified greenhouse-gas emissions associated with a defined organisation, product, activity, event or other subject across a stated boundary and period.

Greenhouse-gas emissions expressed per unit of activity, output, revenue, energy, product or another defined denominator.

Carbon leakage is the risk that emissions are displaced rather than reduced when production, investment or demand shifts to places with weaker or different climate constraints.

The systems in which emission allowances and carbon credits are traded — spanning government-run compliance markets and the voluntary carbon market.

The body of standards, labels and claims rules ensuring that carbon credits represent real, additional, permanent emissions reductions or removals — and are used credibly.

Removing more carbon dioxide from the atmosphere than is emitted — a claim category beyond carbon neutrality, popularised by corporate pledges such as Microsoft's 2030 commitment.

A condition or claim in which a defined carbon footprint is balanced through reductions, removals and, where permitted, offsets according to a specified methodology and period.

A carbon offset is the use of carbon credits or equivalent units to compensate for emissions that remain within a defined claim boundary.

Policy instruments that attach an explicit cost to greenhouse-gas emissions — chiefly carbon taxes and emissions trading systems — to shift decisions toward lower-carbon options.

A carbon registry is a system that records carbon units, ownership, transfers, retirements and project information to support traceability and avoid double counting.

The process of taking carbon dioxide from the atmosphere and durably storing it in geological, terrestrial, oceanic or product reservoirs.

A carbon credit issued for actively removing CO₂ from the atmosphere — priced far above avoidance credits and increasingly mandated as the end-state of credible offset portfolios.

The capture of carbon dioxide from the atmosphere and its storage in vegetation, soils, oceans, products or geological formations for a period of time.

Any process or reservoir that removes more carbon from the atmosphere than it releases — forests, oceans and soils being the great natural sinks.

The absolute quantity of carbon held in a reservoir — biomass, deadwood, litter, soil or ocean — at a point in time; the measurement unit of land carbon accounting.

A tax levied per tonne of CO₂-equivalent emissions — the price-certainty instrument of carbon pricing, deployed in dozens of jurisdictions.

Electricity produced at large power stations — fossil, nuclear or hydro — located away from consumers and delivered over high-voltage transmission networks.

The tradable credit issued under the Kyoto Protocol's Clean Development Mechanism, each representing one tonne of CO₂-equivalent reduced by a registered project in a developing country.

A Claims Code of Practice is a set of rules or guidance for making sustainability or climate claims in a way that is clear, evidenced and not misleading.

Access to cooking fuels and technologies — electricity, LPG, biogas, ethanol, improved biomass — that replace the health- and climate-damaging use of open fires and basic stoves.

The Kyoto Protocol's project-based flexibility mechanism that generated Certified Emission Reductions from mitigation projects in developing countries.

Energy sources that produce little or no greenhouse-gas emissions in operation — a broader umbrella than "renewable" because it can include nuclear and other low-carbon sources.

A power-sector regulation requiring utilities or retailers to supply a rising share of electricity from clean — not only renewable — sources, with tradable credits for compliance.

A North American carbon offset registry and standard-setter — founded by California in 2001 — issuing credits for voluntary and compliance markets.

The process of adjusting human or natural systems to actual or expected climate and its effects in order to reduce harm or take advantage of beneficial opportunities.

A change of climate attributed to human activity that alters the composition of the global atmosphere, additional to natural climate variability — the defining environmental challenge of the century.

The structured appraisal of how climate change affects — and is affected by — a project, plan or asset, now embedded in environmental assessment and adaptation planning practice.

Deliberate large-scale intervention in the climate system to counteract human-caused warming — spanning carbon dioxide removal and the far more controversial solar radiation modification.

Human action that reduces greenhouse-gas emissions or enhances removals from the atmosphere in order to limit the magnitude of climate change.

The capacity of people, ecosystems, institutions and supply chains to anticipate, absorb, adapt to and recover from climate disruption while retaining their essential functions.

The potential for adverse consequences arising from the interaction of climate-related hazards, exposure, vulnerability and responses to climate change.

Climate scenario analysis is a structured exercise that tests how different plausible climate-related futures could affect strategy, financial position, operations or resilience.

The amount of global surface warming expected from a doubling of atmospheric carbon dioxide, central to projecting future climate change.

The propensity of people, ecosystems or assets to be adversely affected by climate hazards, combining sensitivity and adaptive capacity.

A systematic process for ensuring that infrastructure and investments are resilient to current and future climate conditions.

Coal phase-out is the planned reduction and closure of coal use or coal-fired power generation over a defined period.

Supplying ships at berth with shore-side electricity so auxiliary engines can be switched off, cutting port emissions and noise.

Combined heat and power is the simultaneous generation of electricity and useful heat from the same fuel or energy source.

Energy projects owned, governed or substantially shaped by local communities, from cooperatively owned renewables to collective purchasing.

A compliance carbon market is a regulated system where covered entities must surrender allowances or credits to meet legal emissions obligations.

A grid-scale storage technology that compresses air into caverns or vessels when power is surplus and releases it through turbines when needed.

Greenhouse gas emissions attributed to the goods and services a country or population consumes, wherever in the world those emissions occurred.

A contribution claim states that an organisation has supported a climate or sustainability outcome without claiming that the contribution neutralises or offsets its own impact.

Paving materials engineered to stay cooler than conventional asphalt, by reflecting more sunlight or retaining and evaporating water, reducing urban heat.

A roofing system designed to reflect more sunlight and absorb less heat than a standard roof, lowering building cooling demand and urban temperatures.

Core Carbon Principles are integrity criteria used to assess whether carbon credits meet threshold expectations for governance, emissions impact and sustainable development safeguards.

A corporate PPA is a power purchase agreement entered into by a company or organisation to buy electricity or related attributes from a generator.

Corresponding adjustments are accounting adjustments used under international climate accounting to avoid double counting of transferred mitigation outcomes between countries.

CORSIA is the Carbon Offsetting and Reduction Scheme for International Aviation, a sectoral scheme for addressing growth in international aviation emissions.

Credit retirement is the act of permanently taking a carbon credit out of circulation so it can no longer be transferred or used for another claim.

A crediting period is the defined time during which an activity can generate credits under a programme, methodology or approval.

Curtailment is the reduction of available electricity generation below what could otherwise be produced, often because of grid constraints or supply-demand conditions.

Designing buildings to use controlled natural light indoors, cutting electric lighting — which accounts for roughly a third to half of commercial-building electricity.

The sustained reduction of greenhouse-gas emissions from an economy, sector, organisation, product or activity through structural, technological and behavioural change.

Demand response is the adjustment of electricity use in response to grid conditions, price signals or reliability needs.

Utility programmes that plan, implement and monitor activities to encourage consumers to modify their level and pattern of electricity use.

A clean-burning, LPG-like fuel gas producible from methanol derived from biomass, waste or captured CO2, used as a lower-carbon fuel and LPG blend.

An engineered process that separates carbon dioxide directly from ambient air for subsequent durable storage or use.

Small-scale generation, storage and controllable loads — rooftop solar, batteries, EVs, smart appliances — connected at the distribution grid near the point of use.