To avoid giving credits to projects that would have happened anyway, rules have been specified to ensure additionality of the project i.e. to ensure the project reduces emissions more than would have occurred in the absence of the project. A project is additional if its proponents can document that realistic alternative scenarios to the proposed project would be more economically attractive or that the project faces barriers that carbon finance helps it overcome.

Alternative Energy

Energy derived from non-fossil fuel sources.


The envelope of gases surrounding the earth and bound to it by the earth’s gravitational attraction.


A fuel produced from dry organic matter or combustible oils produced by plants. Examples of biofuel include alcohols (from fermented sugar), black liquor from the paper manufacturing process, wood and soybean oil.


The total dry organic matter or stored energy content of living organisms. Biomass can be used for fuel directly by burning it (e.g. wood), indirectly by fermentation to an alcohol (e.g. sugar) or extraction of combustible oils (e.g. soya beans).

Carbon Dioxide (CO2)

A naturally occurring gas, it is also a by-product of burning fossil fuels and biomass, as well as land-use changes and other industrial processes. About a third of human-caused carbon dioxide emissions come from power plants, another third from vehicles, and the remaining from other commercial enterprises and households.

Carbon Footprint

A calculation of the weight of carbon dioxide equivalent emitted into the atmosphere as a result of the activities of an individual or organisation. For example, a passenger’s share of the CO2 emissions from a return flight from London to New York is 2,230kg. The average UK driver drives 12,000 miles per year, this equates to 3.92 tonnes of CO2 emissions (source:

Carbon offsets/offsetting

A mechanism by which the impact of emitting a tonne of CO2 can be negated or cancelled out by either avoiding the release of a tonne elsewhere, or absorbing a tonne of CO2 from the air that otherwise would have remained in the atmosphere.


The Kyoto Protocol establishes the “clean development mechanism” (CDM) to enable Annex I Parties (listed in Annex B of the Kyoto Protocol) to finance emission-reduction projects in the countries of non-Annex I Parties. These Annex I Parties will receive certified emission reductions (CERs) for doing so. The goals of the CDM are: (1) to assist non-Annex I Parties in achieving sustainable development and in contributing to the ultimate objective of the convention and (2) to assist Annex I Parties in meeting their targets. (Source: European Environment Agency).


A metric measure used to compare the emissions from various greenhouse gases based upon their global warming potential (GWP). Carbon dioxide equivalents are commonly expressed as ‘million metric tonnes of carbon dioxide equivalents (MMTCDE)’. (Source: European Environment Agency).


The average trend of weather, including its variability in a geographical region. The averaging period is typically several decades.

Climate change

A change in climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability over comparable time periods (UNFCCC definition).

Eden Project

An environmental education and research facility in Cornwall, UK in which the world’s principal eco-systems are reproduced for the promotion of the study and appreciation of flora horticulture; the environment and the advancement of renewable energy; ecology and conservation; and protection of the world’s endangered plants and trees. As part of BP Target Neutral, BP partnered with The Eden Project to pilot a Carbon Credit Program for Eden visitors from July to September, 2005.

Emissions (UNFCCC definition)

The release of greenhouse gases and/or their precursors into the atmosphere over a specified area and period of time.

Emissions trading

A market-based approach to achieving environmental objectives that allows those that reduce greenhouse gas emissions below a target level to trade the excess reductions to offset emissions at another source inside or outside the country.

Energy efficiency

The ratio of energy output to input of a conversion process/system.

Fossil Fuels

Carbon-based fuels formed in the ground over very long periods, including coal, oil and natural gas.

Fuel Cell

An electrochemical device, like a battery, that combines hydrogen and oxygen to produce electricity, heat and water. The source of hydrogen can be either pure hydrogen or a number of other fuels (such as methanol or other hydrocarbons) which are first converted to hydrogen and CO2.

Fuel Switching

Supplying energy services using different fuels. Often used to refer to actions that reduce CO2 emissions from electric utilities by switching from coal to natural gas.

Global warming

The view that the earth’s temperature is being increased, in part due to emissions of greenhouse gases associated with human activities such as burning fossil fuels, biomass burning, cement manufacture, cow and sheep rearing, deforestation and other land-use changes.

Greenhouse effect

The trapping of heat by naturally occurring heat-retaining atmospheric gases (water vapour, carbon dioxide, nitrous oxide, methane and ozone) that keeps the earth about 30° C (60° F) warmer than if these gases did not exist.

Greenhouse gases (GHGs)

Gases in the earth’s atmosphere that absorb and re-emit infra-red radiation. These gases occur through both natural and human-influenced processes. The major GHG is water vapour. Other primary GHGs include CO2, methane – from landfill sites and flatulent cattle; nitrous oxide (N2O) – from vehicle exhaust fumes; perfluorocarbons (PFCs) – produced in the making of semi-conductors; hydrofluorocarbons (HFCs) – used for refrigeration; and sulphur hexafluoride (SF6) – a by-product of aluminium manufacturing and the electronics industry.


Window-dressing by governments or businesses intended to make them look environmentally friendly.

Intergovernmental Panel on Climate Change

Panel established in 1988 by governments under the auspices of the World Meteorological Organization and the UN Environment Programme. It prepares assessments, reports and guidelines on: the science of climate change and its potential environmental, economic and social impacts; technological developments; possible national and international responses to climate change; and cross-cutting issues.

Kyoto Protocol

This agreement commits signatories to collectively cut their greenhouse gas emissions by 5.2% by 2012. 141 countries ratified the protocol.


A private or municipal site where non-hazardous solid or municipal waste is buried.


One of the six greenhouse gases to be controlled under the Kyoto Protocol produced through anaerobic decomposition of waste in landfills, animal digestion, decomposition of animal wastes, production and distribution of natural gas and oil, coal production, and incomplete fossil-fuel combustion.


Neutralise means to counterbalance and reduce the effect of your vehicle’s CO2 emissions.

Non-Governmental Organizations or NGO’s

NGOs can include registered non-profit organizations and associations from business and industry, environmental groups, cities and municipalities, academics, and social and activist organisations.

Ozone Layer

A region of the upper atmosphere, between about 10 and 20 miles (15 and 30 kilometres) in altitude, containing a relatively high concentration of ozone sufficient to block most ultraviolet radiation from the sun.


To reduce is to make something smaller in size, number, extent, degree, or intensity. There are many ways to decrease your vehicle’s emissions – use your car less; walk or cycle on short journeys, drive more efficiently and regularly check your tyres are properly pumped (soft tyres can increase your fuel bill by 8%).

Renewable Energy

Energy sources that are sustainable, and include non-carbon technologies such as solar energy, hydropower, wind, wave and tidal as well as carbon-neutral technologies such as biomass.


Substitute for a more energy efficient product (fuel or lubricant) or vehicle. Diesel engines are up to 20% more fuel efficient than petrol.

Sustainable Development

Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

United Nations Framework Convention On Climate Change (UNFCCC)

The Convention was adopted on 9 May 1992 in New York and signed at the 1992 Earth Summit in Rio de Janeiro by more than 150 countries and the European Community. Its ultimate objective is the “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.” Its aim was to return greenhouse gas emissions not controlled by the Montreal Protocol to 1990 levels by the year 2000. The Convention entered into force in March 1994.


To check whether or not something is true by examination, investigation, or comparison. Verifiers of emission reduction projects check that the emission reductions have occurred and have been calculated correctly from the previous emission level.

Verified Emission Reduction (VER)

One VER saves one tonne of CO2 from being released into the atmosphere. The price of carbon credits we buy can vary in price between €1.50 to over €30.

These definitions include some produced by the International Petroleum Industry Environmental Conservation Association (3rd edition, 2001).