California Climate Change Glossary

Letter C

Cap and Trade. Cap and Trade is a market-based policy tool for protecting human health and the environment. A cap and trade program first sets an aggressive cap, or maximum limit, on emissions. Sources covered by the program then receive authorizations to emit in the form of emissions allowances, with the total amount of allowances limited by the cap. Each source can design its own compliance strategy to meet the overall reduction requirement, including sale or purchase of allowances, installation of pollution controls, implementation of efficiency measures, among other options. Individual control requirements are not specified under a cap and trade program, but each emissions source must surrender allowances equal to its actual emissions in order to comply. Sources must also completely and accurately measure and report all emissions in a timely manner to guarantee that the overall cap is achieved. (EPA)

Capital Costs. Costs associated with the capital or investment expenditures on land, plant, equipment and inventories. Unlike labor and operating costs, capital costs are independent of the level of output. (IPCC)

Capital Stocks. The accumulation of machines and structures that are available to an economy at any point in time to prune goods or render services. These activities usually require a quantity of energy that is determined largely by the rate at which that machine or structure is used. (IPCC)

Carbon Cycle. The global scale exchange of carbon among its reservoirs, namely the atmosphere, oceans, vegetation, soils, and geologic deposits and minerals. This involves components in food chains, in the atmosphere as carbon dioxide, in the hydrosphere and in the geosphere. (EPA)

Carbonaceous Aerosol(s). Aerosol(s) (q.v.) containing carbon. (IPCC)

Carbon Dioxide (CO₂). The greenhouse gas whose concentration is being most affected directly by human activities. CO₂ also serves as the reference to compare all other greenhouse gases (see carbon dioxide equivalents). The major source of CO₂ emissions is fossil fuel combustion. CO₂ emissions are also a product of forest clearing, biomass burning, and non-energy production processes such as cement production. Atmospheric concentrations of CO₂ have been increasing at a rate of about 0.5% per year and are now about 30% above preindustrial levels. (EPA)

Carbon Dioxide Equivalent (CDE). 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 tons of carbon dioxide equivalents (MMTCDE)" or "million short tons of carbon dioxide equivalents (MSTCDE)" The carbon dioxide equivalent for a gas is derived by multiplying the tons of the gas by the associated GWP. MMTCDE= (million metric tons of a gas) * (GWP of the gas) For example, the GWP for methane is 24.5. This means that emissions of one million metric tons of methane is equivalent to emissions of 24.5 million metric tons of carbon dioxide. Carbon may also be used as the reference and other greenhouse gases may be converted to carbon equivalents. To convert carbon to carbon dioxide, multiply the carbon by 44/12 (the ratio of the molecular weight of carbon dioxide to carbon). (EPA)

Carbon Equivalent (CE). A metric measure used to compare the emissions of the different greenhouse gases based upon their global warming potential (GWP). Greenhouse gas emissions in the U.S. are most commonly expressed as "million metric tons of carbon equivalents" (MMTCE). Global warming potentials are used to convert greenhouse gases to carbon dioxide equivalents. Carbon dioxide equivalents can then be converted to carbon equivalents by multiplying the carbon dioxide equivalents by 12/44 (the ratio of the molecular weight of carbon to carbon dioxide). Thus, the formula to derive carbon equivalents is: MMTCE = (million metric tons of a gas) * (GWP of the gas) * (12/44) (EPA)

Carbon Flux. Shifts or flows of carbon over time from one pool to another. (Lenn)

Carbon Sequestration. The uptake and storage of carbon. Trees and plants, for example, absorb carbon dioxide, release the oxygen and store the carbon. Fossil fuels were at one time biomass and continue to store the carbon until burned. (EPA)

Carbon Sinks. Carbon reservoirs and conditions that take in and store more carbon (carbon sequestration) than they release. Carbon sinks can serve to partially offset greenhouse gas emissions. Forests and oceans are common carbon sinks. (EPA)

CCSM3. Community Climate System Model version 3. One of the world's most advanced climate model used extensively by organizations to predict the consequences of climate change. (Lenn)

CFCs - Chlorofluorocarbons and Related Compounds. This family of anthropogenic compounds includes chlorofluorcarbons (CFCs), bromofluorcarbons (halons), methyl chloroform, carbon tetrachloride, methyl bromide, and hydrochlorofluorcarbons (HCFCs). These compounds have been shown to deplete stratospheric ozone, and therefore are typically referred to as ozone depleting substances. The most ozone-depleting of these compounds are being phased out under the Montreal Protocol. (EPA)

Clean Development Mechanisms. Article 12 of the Kyoto Protocol provides for the CDM whereby developed countries are able to invest in emissions reducing projects in developing countries to obtain credit to assist in meeting their assigned amounts. The details of the CDM have yet to be negotiated at the international level. However, it does allow countries to use credits obtained from the year 2000 for the purposes of meeting their assigned amounts. Participation is voluntary, and open to private and public entities alike on a Party-approved basis. (Australia)

Climate. The average weather (usually taken over a 30-year time period) for a particular region and time period. Climate is not the same as weather, but rather, it is the average pattern of weather for a particular region. Weather describes the short-term state of the atmosphere. Climatic elements include precipitation, temperature, humidity, sunshine, wind velocity, phenomena such as fog, frost, and hail storms, and other measures of the weather. (EPA)

Climate Change (also referred to as 'global climate change'). The term 'climate change' is sometimes used to refer to all forms of climatic inconsistency, but because the Earth's climate is never static, the term is more properly used to imply a significant change from one climatic condition to another. In some cases, climate change' has been used synonymously with the term, 'global warming'; scientists however, tend to use the term in the wider sense to also include natural changes in climate. See also Enhanced Greenhouse Effect. (EPA)

Climate Change Action Plan. Unveiled in October, 1993 by President Clinton, the CCAP is the U.S. plan for meeting its pledge to reduce greenhouse gas emissions under the terms of the Framework Convention on Climate Change (FCCC). The goal of the CCAP is to reduce U.S. emissions of anthropogenic greenhouse gases to 1990 levels by the year 2000. The CCAP, which consists of some 50 voluntary federal programs that span all sectors of the economy, uses a win-win approach by helping program partners save energy, save money, and gain access to clean technology while also reducing greenhouse gas emissions. (EPA)

Climate Change Commitment. TTerm introduced by researchers of the National Center of Atmospheric Research (NCAR) in Boulder, Colorado, to clarify the seriousness of climate change to non-climatologists. It means the amount of climate change that will inevitably occur in the coming century as a result of human behavior in the 20th century. (Lenn)

Climate Feedback. An atmospheric, oceanic, terrestrial, or other process that is activated by the direct climate change induced by changes in radiative forcing. Climate feedbacks may increase (positive feedback) or diminish (negative feedback) the magnitude of the direct climate change. (EPA)

Climate Forecast. The result of an attempt to produce a most likely description or estimate of the actual evolution of the climate in the long term. (Lenn)

Climate Lag. The delay that occurs in climate change as a result of some factor that changes only very slowly. For example, the effects of releasing more carbon dioxide into the atmosphere may not be known for some time because a large fraction is dissolved in the ocean and only released to the atmosphere many years later. (EPA)

Climate Model. A quantitative way of representing the interactions of the atmosphere, oceans, land surface, and ice. Models can range from relatively simple to quite comprehensive. Also see General Circulation Model. (EPA)

Climate Modeling. The simulation of the climate using computer-based models. Also see General Circulation Model. (EPA)

Climate Projection. A description of the response of the climate system to emission or concentration scenarios of greenhouse gases and aerosols, or radiative forcing scenarios, often based upon simulations by climate models. Climate projections are subject to uncertainty, because they are typically based on assumptions concerning future socio-economic and technological developments that may or may not be realized. (Lenn)

Climate Sensitivity. The equilibrium response of the climate to a change in radiative forcing; for example, a doubling of the carbon dioxide concentration. (EPA)

Climate System (or Earth System). The atmosphere, the oceans, the biosphere, the cryosphere, and the geosphere, together make up the climate system. (EPA)

Clean Development Mechanisms. Investments of developed countries in emissions reducing projects in developing countries to obtain credit to assist in meeting their assigned amounts. The details of the CDM have yet to be negotiated at the international level. (Lenn)

Cloud Condensation Nuclei. Airborne particles that serve as an initial site for the condensation of liquid water and which can lead to the formation of cloud droplets. (IPCC)

CO₂-Equivalents. A metric measure used to compare the emissions of various greenhouse gases based upon their Global Warming Potential (GWP). The concentration of CO₂ that would give the same amount of radiative forcing as the given mixture of CO2 and other greenhouse gases. Essentially, they sum the radiative forcing of all trace gases and treat the total forcing as if it comes from an equivalent CO₂ concentration. (Lenn)

CO₂ Fertilization. The enhancement of plant growth as a result of elevated atmospheric CO₂ concentrations. (IPCC)

Concentration Scenarios. Projections of greenhouse gas concentrations derived from emission scenarios and used as input into a climate model to compute climate projections. (Lenn)

Cogeneration. The process by which two different and useful forms of energy are produced at the same time. For example, while boiling water to generate electricity, the leftover steam can be sold for industrial processes or space heating. (EPA)

Commercialization. Sequence of actions necessary to achieve market entry and general market competitiveness of new innovative technologies, process and products. (IPCC)

Compost. Decayed organic matter that can be used as a fertilizer or soil additive. (EPA)

Conference of the Parties (COP). The COP is the collection of nations which have ratified the Framework Convention on Climate Change (FCCC), currently over 150 strong, and about 50 Observer States. The primary role of the COP is to keep the implementation of the Convention under review and to take the decisions necessary for the effective implementation of the Convention. The first COP (COP 1) took place in Berlin from March 28th to April 7th, 1995, and was attended by over 1000 observers and 2000 media representatives. (EPA)

Cost-effective. A criterion that specifies that a technology or measure deliver a good or service at equal or lower cost than current practice. (IPCC)

Cryosphere. The frozen part of the Earth's surface. The cryosphere includes the polar ice caps, continental ice sheets, mountain glaciers, sea ice, snow cover, lake and river ice, and permafrost. (EPA)