CO2 Glossary

Understanding climate change can be a complicated business – hopefully this glossary will help!

Afforestation: Re-establishing forests in areas which have formerly been cleared for farming or timber harvesting.

Biomass: Organic non-fossil material of biological origin such as rape or palm oil which may be used as a renewable energy source.

Biogas: Methane gas produced by the natural degrading and decomposition of organic matter. The gases produced, carbon dioxide and methane, can be collected by a series of low-level pressure wells and can be processed into a medium Btu gas that can be burned to generate steam or electricity.

Carbon dioxide (CO2): A colourless, odourless non-combustible gas with the formula CO2 that is present in the atmosphere. It is formed by the combustion of carbon and carbon compounds (such as fossil fuels and biomass), by respiration of animals and plants, and by the gradual oxidation of organic matter in the soil.

Carbon equivalent (CO2e): A measure used to compare the emissions of the different greenhouse gases based upon relating their global warming potential to that of carbon dioxide.

Carbon footprint: The amount of Carbon Dioxide which and individual or organisation produces. Usually measured in tonnes per year.

Carbon offset: A compensation for the impact of a company's or individual’s emissions by avoiding or sequestering an equal amount of greenhouse gases at another site.

Clean Development Mechanism (CDM): A provision in the Kyoto Protocol that enables industrialised countries to finance emissions-avoiding projects in developing countries and receive credit for doing so. Administered by the United Nations Framework Convention on Climate Change (UNFCCC).

Climate change: The long-term fluctuations in temperature, precipitation, wind, and all other aspects of the Earth's climate. Also a popular term for current changes in the Earth's climate commonly attributed to the increase in atmospheric greenhouse gas concentrations since the start of the industrial revolution.

Direct emissions: Emissions that are produced by a source controlled by a company. Examples include operations within a company-owned factory, or petrol burned in a company car. See also "indirect emissions."

Emissions credit: Under a cap-and-trade emissions trading system, an allowance received by an organization for avoided emissions that may be sold or traded to another organization, allowing the second organization to exceed its emissions level.

Fossil fuel: Petroleum, coal, and natural gas and other carbon deposits that can be burned for heat or power.

Geothermal Energy: Energy derived from heat transferred from the earth's molten core to underground deposits of dry steam (steam with no water droplets), wet steam (a mixture of steam and water droplets), hot water, or rocks lying fairly close to the earth's surface.

Global warming: A popular term used to describe the increase in average global temperatures due to the greenhouse effect.

Greenhouse effect: A popular term used to describe the roles of water vapour, carbon dioxide, and other gases in keeping the Earth's surface warmer than it would be otherwise. These gases are relatively transparent to incoming shortwave radiation, but are relatively opaque to outgoing lon gwave radiation. The latter radiation, which would otherwise escape to space, is trapped by these gases within the lower levels of the atmosphere. The subsequent re-radiation of some of the energy back to the surface maintains surface temperatures higher than they would be if the gases were absent.

Greenhouse gases (GHG): Those gases, such as water vapour, carbon dioxide, tropospheric ozone, nitrous oxide, and methane, that are transparent to solar radiation but opaque to outgoing long wave radiation. Their action is similar to that of glass in a greenhouse.

Indirect emissions: Emissions that result from a company activity, but are produced by a source external to the company. One common example is use of electricity provided by a commercial provides. The company uses the electricity to run lights or office equipment, but the electric utility is producing the power and the emissions.

Kyoto Protocol: An international agreement struck by 159 nations attending the Third Conference of Parties (COP) to the United Nations Framework Convention on Climate Change (held in December of 1997 in Kyoto, Japan) to reduce worldwide emissions of greenhouse gases. If ratified and put into force, signatory countries must reduce their greenhouse gas emissions by pre-specified amounts.

Megawatt (MW): A standard measure of electric power plant generating capacity; a megawatt equals one thousand kilowatts or 1 million watts

Methane: A colourless, odourless, tasteless gas composed of one molecule of carbon and four of hydrogen. Highly flammable, it is the main constituent of "natural gas," which is used as a fuel and for manufacturing chemicals. The global warming potential of methane is 21 times that of CO2.


Offsets: See "carbon offsets."

Renewable energy: Energy derived from resources that are regenerative or for all practical purposes cannot be depleted. Types of renewable energy resources include moving water (hydro, tidal and wave power), thermal gradients in ocean water, biomass, geothermal energy, solar energy, and wind energy. Municipal solid waste (MSW) is also considered to be a renewable energy resource.

Sequsetration: Trees, plants and crops absorb CO2 through photosynthesis and remove it from the atmosphere by storing it as carbon in biomass (tree trunks, branches, foliage and roots) and soils.

Tonne: A metric tonne is 1000kg or

United Nations Framework Convention On Climate Change (UNFCC): The international treaty unveiled at the United Nations Conference on Environment and Development in 1992, which commits signatory countries to stabilize anthropogenic (i.e., human-induced) greenhouse gas emissions to "levels that would prevent dangerous anthropogenic interference with the climate system."