Tabitha Whiting
Tabitha WhitingContent Marketing
Carbon offsetting and removal: a glossary of terms
There's lots of terminology to get your head around when it comes to climate change and carbon offsetting – so we've put together this carbon offsetting and removal glossary to help.April 11, 2022
A definition of tCO2e

Carbon offsetting and removal can be a complex topic – including the language used.

What's the difference between carbon neutral and net zero? What does permanence mean in the context of carbon offsetting? And why the hell do we measure carbon emissions as tCO2e? There's a lot to get your head around, but language should never be a barrier in your climate journey – so we've put together a glossary of terms to bring all that terminology into one convenient place.

We'd recommend bookmarking this one to keep it safe for when you need it again!


In climate change, adaptation refers to any actions taken to reduce vulnerability to the impact of climate change. This includes actions to reduce human vulnerability, such as installing flood defences in low-lying communities. It also includes actions protecting the natural world, such as animal species evolving to exist in warmer climates (nb: currently the climate is changing faster than species are able to adapt to the changes, resulting in increased biodiversity loss).


A project has resulted in emissions reductions or removals in addition to what would have occurred in the absence of the project. 

For more detail, go to our deep dive blog: Additionality in carbon offsetting, explained.


Planting new forests on land which has historically not been forest.

For more detail, go to our deep dive blog: Creating new forests for carbon removal: a deep dive on afforestation


In carbon offsetting, the ‘baseline’ refers to the amount of greenhouse gas emissions that would have taken place in the ‘business-as-usual’ scenario i.e. if the carbon offset project did not exist.

Every carbon offset project needs to calculate a baseline as part of the project design and development, because it is used as the reference point that the project’s impact against: the actual emissions avoided or removed during the project’s lifetime are measured using this baseline to determine overall impact.

For more information: Avoiding overestimation in carbon offset projects, explained


A carbon-rich material similar to charcoal, but produced by a specific method of heating biomass waste in a low oxygen environment. It is then applied to soil where the carbon will be safely stored, whilst also improving the quality of the soil for plant growth.

For more detail, go to our blog: An overview of carbon offset project types: biochar to reforestation to direct air capture


Biodiversity refers to the variety of plant and animal life on earth – or in a particular habitat or location. A high variety of plant and animal life is essential to support the healthy ecosystems that we rely on to provide us with the air we breathe and the food we eat.

Bio-oil sequestration

Waste biomass (typically from agriculture) is converted into a stable, carbon-rich liquid known as 'bio-oil'. The bio-oil is then injected deep underground, permanently storing the carbon.

Blue carbon

The carbon captured by living organisms in coastal (e.g., mangroves, salt marshes, seagrasses) and marine ecosystems, stored in biomass and sediments.

For more detail, go to our blog: An overview of carbon offset project types: biochar to reforestation to direct air capture

Carbon capture

A process in which CO2 from industrial and energy-related sources is separated (captured), conditioned, and compressed. It is then stored safely, known as carbon capture and storage, or used to create products such as sparkling water or building materials, known as carbon capture and usage.

Carbon credit

A unit used to represent emissions removal or reduction/avoidance, sold by carbon projects to carbon buyers as a way to compensate for emissions produced elsewhere. 1 carbon credit is equal to 1 tonne of CO2e reduction or removal.

Read more: How much do carbon credits cost?

Carbon cycle

The carbon cycle is a series of natural processes that maintain the balance of carbon dioxide in the atmosphere. This includes rock weathering, ocean carbon removal, carbon absorbed and stored in plants, and the creation of fossil fuels through decomposing animal matter being turned into carbon-rich sediment.

Carbon drawdown

Used as a synonym for carbon removal or CDR.

Carbon emissions

Carbon dioxide that enters the atmosphere. This happens naturally through biological processes like respiration but are also caused by human activities, especially the burning of fossil fuels to generate energy. Carbon dioxide is one of several greenhouse gases that contribute to the greenhouse effect by absorbing infrared radiation, trapping heat and causing global warming.

Carbon insetting

The implementation of nature-based projects e.g. forestry, renewable energy into a company’s own value chain: bringing practices that aim to reduce the carbon emissions from the company's activities within the business itself (in comparison to carbon offsetting, which utilises completely external carbon projects to neutralise emissions). An example could be a manufacturing business installing solar panels onto the rooftop of their warehouse and using the generated energy to power their machinery.

For more information: take a look at this explainer from WeForum.

Carbon footprint

The total amount of greenhouse gas (GHG) emissions produced by the actions of an individual, product, organisation or country, used as a measure of their climate change impact.

Carbon market

A market where carbon credits can be bought and sold, creating a system where countries, businesses etc can be financially incentivised to reduce their carbon emissions through putting emission limits in place.

Carbon negative

A state in which a company, individual, or country is responsible for a negative amount of carbon emissions i.e. less than zero. This means that they are offsetting more carbon emissions than they create via carbon removal or emissions avoidance projects.

Carbon neutral

Where the total amount of greenhouse gas (GHG) emissions produced is offset in its entirety by either carbon removal or emissions avoidance, offsetting the impact. The term is usually used in association with products or businesses.

NB this is different to net zero, where offsets need to actively remove carbon from the atmosphere – read more in our blog: The true definition of net zero, explained.

Carbon offset certificate

When a carbon credit is sold a carbon offset certificate is issued to the buyer to prove that the credit has been retired on their behalf.

For more information: Forget sealing wax: designing a certificate in step with the times

Carbon offset projects

Projects designed with the purpose of carbon removal or emissions reduction, and which use carbon offset credits as a financing mechanism: once verified by a carbon standard the project issues carbon credits equivalent to the amount of carbon the project will remove or avoid, which can then be purchased by individuals or businesses who want to offset their own emissions.

For more, take a look at our overview of different carbon offset project types.

Carbon offsetting

Compensating for carbon emissions by financing projects that claim to make an equivalent reduction in carbon emissions. 

Carbon registry

Online systems to track carbon credits being issued to project developers and purchased by buyers. This includes retiring credits once purchased to avoid the risk of double counting; a certificate will usually be sent to the buyer as proof of retirement.

Read more: What's a carbon registry?

Carbon removal or Carbon Dioxide Removal (CDR)

Physically removing existing carbon from the atmosphere and storing it. This happens in nature (forests, soils, oceans) but it can also be achieved by technological solutions e.g. Direct Air Capture. 

Read more: what's the difference between emissions avoidance and carbon removal in offsetting? and Every company should be buying carbon removal today – here's why.

Carbon sink

A reservoir that absorbs and stores carbon emissions. Usually refers to natural environments such as forests, oceans, and soil.

Carbon standard

There’s currently no government set standard for projects in the voluntary carbon market, so standards are being set by trusted, independent standards. The major ones include Gold Standard, Verified Carbon Standard (Verra), and Puro.Earth.

Read more: What's the role of a carbon standard?


Important positive implications of carbon offset projects that go beyond carbon, to have other social and environmental impacts e.g. biodiversity or job creation.

Read more: How to cut emissions, reduce poverty, and protect biodiversity at the same time – the co-benefits of carbon offsetting

Compliance market

A carbon marketplace governed by law, stating that companies (typically high-emitters like airlines and oil and gas) have a cap on the amount of greenhouse gases they are allowed to emit each year, and have to buy carbon credits if they go over this.

Concrete mineralisation

Due to the minerals found in cement, the process of carbon mineralisation (see: mineralisation) can also be applied during the process of making concrete, locking CO2 in concrete and providing a form of long-lived carbon storage.

For more detail, go to our blog: An overview of carbon offset project types: biochar to reforestation to direct air capture

Corporate Sustainability Reporting (CSR)

Companies that are focused on improving their environmental and sustainability practices conduct regular reporting on their progress – typically including progress on reducing their own carbon emissions, any any other sustainability initiatives. This has largely been on a voluntary basis, but more and more regulations are being put in place to enforce businesses to report on their climate actions – including the US SEC Climate Disclosure proposal and the EU Corporate Sustainability Reporting Directive.

For more information: New corporate sustainability reporting rules will have big implications for the logistics industry


The act of clearing a forest. Typically done to harvest wood as a resource, and/or to clear land for some other economic use e.g. as a palm oil plantation.

Direct Air Capture (DAC)

The process of capturing CO2 directly from the atmosphere. Chemicals are used which bind with the CO2 in the air, and the CO2 is then separated to produce a stream of concentrated CO2. This CO2 can then be stored or used in an end product (such as construction) – known as direct air capture and storage (DACS).

For more detail, go to our deep dive blog: How to suck all that carbon we’ve emitted back out of the atmosphere – a deep dive on Direct Air Capture

Double counting or double claiming or double issuing

When a carbon credit is used more than once, even though this would not further reduce or avoid emissions. When projects are certified their carbon credits will be issued and retired in a carbon registry, preventing double counting from being a risk.

Read more: what's double counting in carbon offsetting?

Emissions reduction or emissions avoidance

Future emissions from fossil fuels are avoided or reduced through a project e.g. building a solar farm close to a city which is currently powered by a fossil fuel plant will result in less carbon emissions in the future. 

Read more: what's the difference between emissions avoidance and carbon removal in offsetting?

Enhanced weathering

The speeding up of rock weathering or mineralisation as a way of removing and storing carbon. Rocks are ground up into small particles, increasing surface area and removing CO2 from the atmosphere more quickly.

Read more: Accelerating natural processes for increased carbon removal – a deep dive on enhanced rock weathering

Environmental, Social, and Governance (ESG)

ESG is an umbrella term for embedding environmental, social, and governance (how decisions are made in the company, and who by) principles into a business strategy, aiming to create a plan to minimise any negative impact of the business on people and the planet.

Ex-ante credits

Carbon credits representing carbon removal or emissions avoidance that will take place in the future e.g. purchase of credits to finance the planting of a forest, where removal will take place once trees grow and sequester carbon.

Ex-post credits

Carbon credits representing carbon removal or emissions avoidance that has already taken place and has been measured.

Read more: What's the difference between ex-post, ex-ante, and pre-purchase carbon credits?

Forest conservation

Protecting a forest from being cut down, typically through incentivising landowners via income from carbon credits

For more detail, go to our blog: An overview of carbon offset project types: biochar to reforestation to direct air capture

Forest management

Implementing practices for the stewardship of forests. In carbon removal, this refers specifically to land management practices which result in increased carbon storage within forests.

For more detail, go to our blog: An overview of carbon offset project types: biochar to reforestation to direct air capture

Forestry carbon projects

There are a range of different ways that forests are used to avoid emissions and remove carbon from the atmosphere, which can be grouped together as forestry carbon projects. This includes afforestation, forest conservation, forest management, and reforestation.

NB: forestry carbon offset projects are different to tree planting projects. Read more: The problem with tree planting projects as a way to fight climate change

GLEC framework

The GLEC Framework was developed by the Global Logistics Emissions Council (GLEC). The framework is the only globally recognised methodology for consistent and accurate calculation and reporting of the greenhouse gas emissions from logistics activities across the multi-modal supply chain i.e. covering journeys which use multiple logistics modes e.g sea shipping to air freight to lorry. The framework is aligned with the Greenhouse Gas Protocol, the UN Global Green Freight Action Plan, and CDP reporting.

Read more: Lune’s logistics emissions calculations accredited by Smart Freight Centre under the GLEC Framework

Greenhouse gas emissions

A gas that contributes to the greenhouse effect by absorbing infrared radiation, trapping heat and causing global warming. The primary greenhouse gases are water vapour (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and ozone (O3).


A company or product making itself appear to be environmentally friendly without having done the work to meaningfully reduce its environmental impact. Carbon offsetting can be seen as greenwashing when companies support low-quality projects, are not also reducing their emissions, or approach sustainability as a marketing or PR exercise.

Read more:

High-quality projects

Trusted carbon offset projects that show permanent, additional, and measurable carbon removal or emissions avoidance. They’re often verified (or in the process of being), although this isn’t always the case. They’re also more expensive, as they reflect the true cost of carbon removal/avoidance.

Read more: what makes a high-quality offset?

Intergovernmental Panel on Climate Change (IPCC)

The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change, releasing regular reports on the state of human-caused climate change.

Jj Kk Ll

When a reduction in carbon emissions in one area simply shifts activity producing emissions elsewhere, reducing or negating the decrease in emissions e.g. a forest conservation project results in deforestation being avoided, but the company responsible for deforestation moves to a neighbouring forest and cuts down trees there.

Long-lived carbon storage

Methods that store carbon for hundreds or thousands of years, which have a low risk of being reversed e.g. mineralisation.

Low-quality projects

Carbon offset projects which are not verified and have no proof of permanent, additional, and measurable carbon removal or emissions avoidance. They are typically cheap to purchase but have little or no climate impact – leaving those who buy them at risk of being perceived as greenwashing.

Read more: what makes a high-quality offset?

Subscribe for the latest insights into driving climate positivity
Measurement, reporting, and verification (MRV)

Measurement, Reporting, and Verification (MRV) is part of the process of ensuring quality within carbon projects, aiming to ensure the project's impact aligns with expectations – avoiding the overestimation of impact and, therefore, the oversale of carbon credits. MRV covers the need to 'measure' the amount of carbon emissions reduced or removed by a project which includes ongoing monitoring, to 'report' these findings externally, and have the findings 'verified' by an independent, trusted, third-party.

Read more: avoiding overestimation in carbon projects


Occurs when CO2 in the air reacts with minerals to become a carbonate, permanently storing the CO2 in solid form. This happens naturally, also known as ‘rock weathering’. The process can be sped up by rocks being ground up into small particles, increasing surface area and removing CO2 from the atmosphere more quickly – also known as ‘enhanced weathering’.


In climate change, mitigation refers to any action aiming to prevent further global warming and combat climate change. This includes actions which reduce greenhouse gas emissions taking place in the first place (known as emissions avoidance projects in carbon offsetting) and actions to increase the amount of existing carbon removed from the atmosphere (known as carbon removal projects in carbon offsetting).

Nature-based solutions

Nature-based solutions – also known as natural climate solutions – are  projects that protect, manage, and/or restore natural ecosystems in order to mitigate climate change – and importantly, they do this whilst also addressing other societal issues to create holistic solutions. 

Net-negative materials

Also known as carbon negative building materials. When trees grow they capture carbon, providing a vital store for carbon. But, when trees die (naturally or through issues such as wildfires) this carbon is released. Net-negative materials take biomass waste from sustainably grown trees and use is to create wooden building materials – meaning the carbon continues to be stored within the constructions made with the materials. Once installed the carbon is locked away for 50+ years.

Net zero

When a company reduces their greenhouse gas (GHG) emissions and neutralises the residual amount using carbon removal, resulting in no net impact. NB: this is different from carbon neutral where the emissions offset can be emissions avoidance or carbon removal.

Read more:

Ocean carbon removal

Oceans are a natural carbon sink, absorbing and storing carbon emissions as part of the slow carbon cycle. This happens in a few different ways:

  • Carbon is absorbed directly from the air at the ocean's surface
  • Phytoplankton that live in the ocean convert CO2 into sugars that feed marine animals
  • Carbon is absorbed by the plants in the ocean and coastal areas such as seaweed, mangroves, sea marshes etc.

Read more: Amplifying nature’s climate solution – a deep dive on ocean carbon removal

Oxford Offsetting Principles

The Oxford Principles for Net Zero Aligned Carbon Offsetting – known as the Oxford Offsetting Principles for short – provide a framework for approaching business offsetting in the right way and supporting the growth of the carbon market: balancing immediate action with long-term impact whilst keeping costs feasible and taking into account how purchases should change over time to maintain the maximum possible impact. The main focus is on prioritising a) carbon removal and b) long-lived carbon storage.

Read more: The Oxford Offsetting Principles: how to to maximise carbon offsetting impact

Paris Agreement

The Paris Agreement is a legally binding international treaty on climate change, which was adopted by 196 Parties in December 2015 at COP21 in Paris. The goal of the agreement is for global leaders to meet targets to limit global warming to well below 2 (preferably to 1.5 degrees).


How durable the carbon benefit from carbon removal or emissions avoidance is, taking into account the risk of reversal. For instance, a forest can burn or be cut down in future years so cannot be viewed as permanent.

Read more: Permanence in carbon offsetting, explained.

Pre-purchase carbon credits

Pre-purchase carbon credits are sold today, but are not actually yet issued. This essentially represents a promise from an early-stage carbon project that they will issue carbon credits in the future, once the project is up and running.

Read more: What's the difference between ex-post, ex-ante, and pre-purchase carbon credits?

Project developers

Organisations that design, implement, and manage carbon offset projects e.g. UNDO for enhanced weathering, and Treeconomy for forestry.

Qq Rr

Turning land that has previously been a forest but that has been converted to some other use back into forest.

For more detail, go to our blog: An overview of carbon offset project types: biochar to reforestation to direct air capture


Projects enabling the generation of renewable energy e.g wind turbines, solar farms, reducing reliance on fossil fuels for energy. 

For more detail, go to our blog: An overview of carbon offset project types: biochar to reforestation to direct air capture

Scope 1 emissions

Direct emissions from owned or controlled sources e.g. company vehicles.

Scope 2 emissions

Indirect emissions from the generation of purchased energy e.g. purchased electricity.

Scope 3 emissions

All other indirect emissions that occur in the value chain, including both upstream and downstream emissions e.g. emissions associated with the use of products or services sold or used by an organisation.

Read more: Scope 1, 2, and 3 emissions, explained

Science-based target

A corporate sustainability initiative that meets three criteria: 1) it has a clearly-defined emissions reduction pathway, 2) it has a defined baseline amount and year, as well as target goal date, 3) it’s set in line with the latest climate science needed to meet the goals of the Paris Agreement – as defined the by Science Based Targets Initiative (SBTi).

Read more: How to use Science Based Targets and the Oxford Offsetting Principles for net zero aligned offsetting

Seaweed farming

Seaweed is quick-growing and naturally absorbs carbon dioxide as it grows, making it a crucial natural form of carbon removal. Seaweed farming projects – also referred to as seaweed cultivation or seaweed sequestration – seek to enhance and accelerate this natural process in order to increase carbon removal rates by seaweed.

For more detail, go to our blog: An overview of carbon offset project types: biochar to reforestation to direct air capture


The process of capturing carbon dioxide from the atmosphere, stabilising it in solid or dissolved form, and storing it safely. Usually refers to natural storage e.g. in seaweed or soil.

Short-lived carbon storage

Methods of carbon storage which have a higher risk of being reversed e.g. reforestation.

Soil carbon

Soil is made in part by broken down organic matter, so it contains the carbon that these plants or animals absorbed during their lifetime. This means that soil is a valuable carbon store or sink.

For more detail, go to our blog: An overview of carbon offset project types: biochar to reforestation to direct air capture


Storage (or carbon storage, sequestration) refers to when carbon emissions are collected and safely locked away. This happens as part of the natural carbon cycle when carbon emissions are stored in nature's carbon sinks such as the soil, oceans, and trees. Techniques are also being developed to enhance these processes artificially, for instance taking carbon emissions and injecting them deep underground where they are safely stored for the long-term – this is a crucial part of Carbon Capture and Storage projects, for instance.

Storage can be for the short-term (see: short-lived storage) or the long-term (see: long-lived storage). Whether projects provide storage, and whether this is long- or short-lived is a key element of how carbon projects are categorised.


Sustainability is a broad term, which refers to the ability for something to be maintained at a certain rate or level. In terms of environment, this means that we avoid depleting natural resources in order to protect the planet from ecological degradation. In 1987 the United Nations Brundtland Commission defined sustainability as 'meeting the needs of the present without compromising the ability of future generations to meet their own needs.'

'Business sustainability' is a term commonly used to describe the aim of doing business without negatively impacting the environment.

Sustainability report

A tool for a company or organisation to voluntarily communicate its performance in relation to environmental impact.

Often these reports lack visibility and accountability as a way to approach business sustainability. However, standards are being developed to improve corporate sustainability reporting – notably the Taskforce for Climate-related Disclosure (TCFD), and countries across the world are using these standards to bring in regulations which make it mandatory for companies to report on their environmental impact in a rigorous and transparent way.

Sustainability strategy

A framework or strategy for ensuring a business is sustainable i.e. does not negatively impact the environment. To be truly effective and impactful, a sustainability strategy needs to be deeply embedded at the core of a business – the wider goals, vision, and values of the company.

For more information: Why 9 out of 10 sustainability strategies make no difference to the planet (and how to make sure yours does)

Sustainable Development Goals (SDGs)

The Sustainable Development Goals (SDGs) came about through the UN's largest ever participatory process to find the highest priority goals for global sustainable development between 2015 and 2030.

17 Sustainable Development Goals were determined within the 2030 Agenda for Sustainable Development, which was officially adopted by the UN member states at the 2015 United Nations General Assembly – a global partnership aiming to create a better and more sustainable future for all life on earth.

Read more: How businesses can contribute to the Sustainable Development Goals through (high-quality) offsetting


Greenhouse gases are typically given as tCO2e – tonnes of carbon dioxide equivalent. The equivalent means that the measurement includes greenhouse gases which aren’t carbon dioxide, converted into equivalent amounts of CO2 based on warming potential e.g. methane which has 28-36 times the global warming potential of CO2, so 1 tonne of methane would count as 28-36 tonnes of CO2e.

Read more: How much CO2 do we really emit, visualised

Tipping point

The 'tipping point' in climate change refers to a point of no return, after which point the changes caused by global warming become irreversible. Tipping points identified by climate scientists include ice sheet collapse and large scale death of coral reefs.

Uu Vv
Voluntary carbon market (VCM)

A market enabling the voluntary purchase of carbon credits by a company or individual. This offers a mechanism for financing projects that reduce emissions or remove carbon from the atmosphere, and a way for companies to take climate action by compensating for their emissions or contributing to carbon projects.

Xx Yy Zz

We know there can be a lot to wrap your head around when you’re exploring climate impact and carbon offsetting in a business setting; this isn’t an exhaustive list of all the terminology you might come across! 

That’s also why working with a trusted sustainability partner can be incredibly valuable – at Lune we’ve done the hard work already of becoming experts in how businesses should approach carbon offsetting and removal.

And we’re always happy to chat and answer any questions you may have, no matter what stage of your climate journey you’re at – get in touch.

Subscribe for the latest insights into driving climate positivity-image

Subscribe for the latest insights into driving climate positivity