| Additionality | A carbon project is additional if the reduction in carbon emissions could not have occurred without carbon funding. |
| Allowance | The quantity of carbon dioxide emissions which a company or country is permitted to emit, as a result of regulation. |
| Anaerobic digester | An industrial system that converts waste products into useful energy while reducing methane emissions. More... |
| Anthropogenic | Global warming is believed to be anthropogenic, meaning it is caused by human activity rather than nature. More... |
| Baseline | An estimate of the quantity of carbon that would be emitted by an installation if a carbon project was not carried out. |
| Biogas | A mixture of methane and carbon dioxide generated by anaerobic digestion and can be burned for energy. More... |
| Biomass | Biological material such as dead plants which can be burned as fuel to generate electricity. More... |
| Biomass Combustion | See: Project types... |
| Carbon calculator | A feature on provider websites which helps you calculate how much carbon dioxide is emitted due to your activites. |
Carbon dioxide (CO2) | The greenhouse gas responsible for most of the Earth's warming, generated when burning coal, oil or gas. More... |
Carbon dioxide equivalent (CO2e) | A tonne of CO2e is a quantity of any greenhouse gas which has the same warming effect as a tonne of CO2. More... |
| Carbon neutral | An ideal in which all of a person's or organization's carbon emissions are balanced, resulting in a zero carbon footprint. More... |
| Certification | A formally defined standard relating to the quality of a carbon project, such as the Voluntary Carbon Standard, Clean Development Mechanism and Gold Standard. |
Clean Development Mechanism (CDM) | Helps rich countries meet their targets under the Kyoto Protocol by purchasing carbon from developing countries. |
| Climate change | The series of changes to the Earth's climate which include, and are mostly caused by, global warming. More... |
| Cobenefit | An additional benefit of an carbon project on top of the reduction in carbon emissions, e.g. providing employment. |
| Cost efficiency | The proportion of the money paid to a provider which goes directly to carbon projects. Not all providers publish this. |
| Efficient Lighting | See: Project types... |
| Environmental Buildings | See: Project types... |
Environmental Resources Trust (ERT) | An independent non-profit organization which validates greenhouse gas reduction projects. |
| Forestation | See: Project types... |
| Fossil fuels | Fuels like coal, oil or gas, created in the Earth from fossils, which generated carbon dioxide when burned. More... |
| Fuel Efficiency | See: Project types... |
| Fuel Substitution | See: Project types... |
| Geothermal Power | See: Project types... |
| Global warming | The recent increase in the Earth's temperature, believed to be a result of human greenhouse gas emissions. More... |
Gold Standard (GS) | A strict certification standard for carbon projects, which goes beyond the requirements of the Kyoto Protocol. |
| Green-e | An independent program run by a non-profit which certifies and verifies renewable energy certificates (RECs). |
Greenhouse gas (GHG) | A gas in the atmosphere which causes warming. GHGs include carbon dioxide, methane and nitrous oxide. More... |
| Heat-Electricity Cogeneration | See: Project types... |
| Hydroelectric Power | See: Project types... |
| Industrial Methane | See: Project types... |
Joint Implementation (JI) | Part of the Kyoto Protocol which allows rich countries to meet their targets by purchasing carbon from each other. |
| Kyoto Protocol | An international agreement sponsored by the United Nations aiming to reduce human greenhouse gas emissions. |
| Leachate | Toxic water created when landfill garbage is exposed to rain. It pollutes the ground and emits methane. More... |
| Leakage | A carbon project suffers from leakage if it increases carbon emissions elsewhere. For example, closing down a factory may cause a competing factory to ramp up production. |
| LEED | A rating system which encourages construction of buildings which require less electricity, water and fuels. More... |
| Material Substitution | See: Project types... |
| Measurement | After a project is complete, the quantity of greenhouse gases still emitted is measured. This amount is subtracted from the baseline to confirm the predicted reduction. |
Methane (CH4) | A potent greenhouse gas which is emitted by various industrial and agricultural processes. More... |
| Operator | The local company, installation or organization which is entrusted with running a carbon project. |
| Permanence | If a project captures and stores carbon, the storage must be permanent. This is particularly relevant for forests. |
| Project | A practical scheme to cause a reduction in carbon dioxide emissions, thus acting as a source of carbon credits. |
| Provider | A company or non-profit organization which sells carbon credits, and uses the money to fund projects. |
| Public Transportation | See: Project types... |
| Regulated offset | A carbon credit which a company is required to purchase by law, because it is emitting more than its allowance. |
| Renewable energy | A way of generating energy which uses up no finite resources. Examples include solar, wind and hydro. More... |
Renewable Energy Certificate (REC) | RECs (or Green tags) represent electricity produced from renewable sources. Some are resold as carbon. More... |
| Sequestration | Long-term storage of carbon dioxide in the ground, plants or oceans, e.g. by reforestation. More... |
| Solar Power | See: Project types... |
| Sustainability | The ability of a system to meet both present and future needs. Solar energy is sustainable, crude oil is not. More... |
| Verification | To prevent mistakes or fraud, carbon projects should be verified by a qualified and independent third party. |
| Voluntary carbon offset | A carbon credit purchased by a concerned individual or business out of choice, not as a result of regulation. |
Voluntary Carbon Standard (VCS) | A certification standard for carbon offsets which covers the basic requirements needed for a project to be valid. |
| Wind Power | See: Project types... |