Global Warming Glossary *
C3 plants - Plants that produce a three-carbon compound during photosynthesis, including most trees and agricultural crops such as rice, wheat, soybeans, potatoes and vegetables.
C4 plants - Plants that produce a four-carbon compound during photosynthesis, mainly of tropical origin, including grasses and the agriculturally important crops maize, sugar cane, millet and sorghum.
Calcite - A calcium carbonate (limestone) mineral, used by shell- or skeleton-forming, calcifying organisms such as foraminifera, some macroalgae, lobsters, crabs, sea urchins and starfish. Calcite is less sensitive to ocean acidification than a href="a.html#aragonite">aragonite, also used by many marine organisms. See also ocean acidification.
Cap - Mandated restraint as an upper limit on emissions.
Capacity building - In the context of climate change, capacity building is developing technical skills and institutional capabilities in developing countries and economies in transition to enable their participation in all aspects of adaptation to, mitigation of, and research on climate change.
Carbon capture and storage (CCS) - A process consisting of separation of CO2 from industrial and energy-related sources, transport to a storage location and long-term isolation from the atmosphere.
Carbon dioxide (CO2) - A naturally occurring gas, also a by-product of burning fossil fuels from fossil carbon deposits, such as oil, gas and coal, of burning biomass and of land use changes and other industrial processes. It is the principal greenhouse gas that affects the Earth's radiative balance. It is the reference gas against which other greenhouse gases are measured and therefore has a Global Warming Potential of 1.
Carbon dioxide (CO2) fertilization - The enhancement of the growth of plants as a result of increased atmospheric carbon dioxide (CO2) concentration. Depending on their mechanism of photosynthesisls, , certain types of plants are more sensitive to changes in atmospheric CO2 concentration. In particular, C3 plants generally show a larger response to CO2 than C4 plants.
Carbon intensity - The amount of emissions of CO2 per unit of GDP.
Carbon leakage - The part of emissions reductions in countries that have agreed to a target for their greenhouse-gas emissions that may be offset by an increase of the emissions in the non-constrained countries above their baseline levels. This can occur through (1) relocation of energy-intensive production in non-constrained regions; (2) increased consumption of fossil fuels in these regions through decline in the international price of oil and gas triggered by lower demand for these energies; and (3) changes in incomes (thus in energy demand) because of better terms of trade. Leakage also refers to GHG-related effects of GHG-emission reduction or CO2-sequestration project activities that occur outside the project boundaries and that are measurable and attributable to the activity. On most occasions, leakage is understood as counteracting the initial activity. Nevertheless, there may be situations where effects attributable to the activity outside the project area lead to GHG-emission reductions. These are commonly called spill-over. While (negative) leakage leads to a discount of emission reductions as verified, positive spill-over may not in all cases be accounted for.
Carbon pool - Carbon pools are: above-ground biomass, belowground biomass, litter, dead wood and soil organic carbon.
Carbon price - What has to be paid (to some public authority as a tax rate, or on some emission permit exchange) for the emission of 1 metric ton (~2,205 pounds) of CO2 into the atmosphere.
Catchment - An area that collects and drains rainwater.
CCS-ready - If rapid deployment of CCS is desired, new power plants could be designed and located to be "CCS-ready" by reserving space for the capture installation, designing the unit for optimal performance when capture is added and citing the plant to enable access to storage reservoirs.
Certified Emission Reduction Unit (CER) - Equal to one metric ton (~2,205 pounds) of CO2-equivalent emissions reduced or sequestered through a Clean Development Mechanism project, calculated using Global Warming Potentials.. In order to reflect potential non-permanence of afforestation and reforestation project activities, the use of temporary certificates for Net Anthropogenic Greenhouse Gas Removal was decided by COP 9.
Chagas' disease - A parasitic disease caused by the Trypanosoma cruzi and transmitted by triatomine bugs in the Americas, with two clinical periods: acute (fever, swelling of the spleen, oedemas) and chronic (digestive syndrome, potentially fatal heart condition).
Chemical oxygen demand (COD) - The quantity of oxygen required for the complete oxidation of organic chemical compounds in water; used as a measure of the level of organic pollutants in natural and waste waters.
Chlorofluorocarbons (CFCs) - Heat-trapping gases (greenhouse gases) covered under the 1987 Montreal Protocol and used for refrigeration, air conditioning, packaging, insulation, solvents, or aerosol propellants. Because they are not destroyed in the lower atmosphere, CFCs drift into the upper atmosphere where, given suitable conditions, they break down ozone. These gases are being replaced by other compounds, including hydrochlorofluorocarbons and hydrofluorocarbons, which are heat-trapping gases (greenhouse gases) covered under the Kyoto Protocol.
Cholera - A water-borne intestinal infection caused by a bacterium (Vibrio cholerae) that results in frequent watery stools, cramping abdominal pain, and eventual collapse from dehydration and shock.
Clathrate (methane) - A partly frozen slushy mix of methane gas and ice, usually found in sediments.
Clean Development Mechanism (CDM) - The CDM allows heat-trapping gas (greenhouse gas) emission reduction projects to take place in countries that have no emission targets under the United Nations Framework Convention on Climate Change (UNFCCC) Kyoto Protocol, yet are signatories.
Climate - Climate in a narrow sense is usually defined as the average weather, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period for averaging these variables is 30 years, as defined by the World Meteorological Organization. The relevant quantities are most often surface variables such as temperature, precipitation and wind. Climate in a wider sense is the state, including a statistical description, of the climate system. In various chapters in this report different averaging periods, such as a period of 20 years, are also used.
Climate change - Climate change refers to a change in the state of the - climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings, or to persistent human-induced changes in the composition of the atmosphere or in land use.
Climate change commitment - Due to the thermal inertia of the ocean and slow processes in the biosphere, the cryosphere and land surfaces, the climate would continue to change even if the atmospheric composition were held fixed at today's values. Past change in atmospheric composition leads to a committed climate change, which continues for as long as a radiative imbalance persists and until all components of the climate system have adjusted to a new state. Climate change commitment includes other future changes, for example in the hydrological cycle, in extreme weather and climate events, and in sea level change.
Climate (change) scenario - A plausible and often simplified representation of the future climate, based on an internally consistent set of climatological relationships and assumptions of radiative forcing, typically constructed for explicit use as input to climate change impact models. A "climate change scenario" is the difference between a climate scenario and the current climate.
Climate feedback - An interaction mechanism between processes in the climate system is called a climate feedback when the result of an initial process triggers changes in a second process that in turn influences the initial one. A positive feedback intensifies the original process, and a negative feedback reduces it.
Climate model - A numerical representation of the climate system based on the physical, chemical and biological properties of its components, their interactions and feedback processes, and accounting for all or some of its known properties. The climate system can be represented by models of varying complexity, that is, for any one component or combination of components a spectrum or hierarchy of models can be identified, differing in such aspects as the number of spatial dimensions, the extent to which physical, chemical or biological processes are explicitly represented, or the level at which empirical parameterizations are involved. Coupled Atmosphere-Ocean General Circulation Models (AOGCMs) provide a representation of the climate system that is near the most comprehensive end of the spectrum currently available. There is an evolution towards more complex models with interactive chemistry and biology.
Climate projection - A projection of the response of the climate system to emission or concentration scenarios of heat-trapping gases (greenhouse gases) and aerosols, or radiative forcing scenarios, often based upon simulations by climate models. Climate projections are distinguished from a href="c.html#climate-predictions">climate predictions in order to emphasize that climate projections depend upon the emission/concentration/ radiative forcing scenario used, which are based on assumptions concerning, for example, future socioeconomic and technological developments that may or may not be realized and are therefore subject to substantial uncertainty.
Climate sensitivity - In Intergovernmental Panel on Climate Change (IPCC) reports, equilibrium climate sensitivity refers to the equilibrium change in the annual mean global surface temperature following a doubling of the atmospheric equivalent carbon dioxide concentration. Due to computational constraints, the equilibrium climate sensitivity in a climate model is usually estimated by running an atmospheric general circulation model coupled to a mixed-layer ocean model, because equilibrium climate sensitivity is largely determined by atmospheric processes. Efficient models can be run to equilibrium with a dynamic ocean. The effective climate sensitivity is a related measure that circumvents the requirement of equilibrium. It is evaluated from model output for evolving non-equilibrium conditions. It is a measure of the strengths of the climate feedbacks at a particular time and may vary with forcing history and climate state. The climate sensitivity parameter (units: °C (W m-2)-1) refers to the equilibrium change in the annual mean global surface temperature following a unit change in radiative forcing. The transient climate response is the change in the global surface temperature, averaged over a 20-year period, centered at the time of atmospheric carbon dioxide doubling, that is, at year 70 in a 1% yr-1 compound carbon dioxide increase experiment with a global coupled climate model. It is a measure of the strength and rapidity of the surface temperature response to heat-trapping gas (greenhouse gas) forcing.
Climate system - The climate system is the highly complex system consisting of five major components: the atmosphere, the hydrosphere, the cryosphere, the land surface and the biosphere, and the interactions between them. The climate system evolves in time under the influence of its own internal dynamics and because of external forcings such as volcanic eruptions, solar variations and human-induced forcings such as the changing composition of the atmosphere and land use change.
Climate threshold - The point at which external forcing of the climate system, such as the increasing atmospheric concentration of heat-trapping gases (greenhouse gas es), triggers a significant climatic or environmental event which is considered unalterable, or recoverable only on very long time-scales, such as widespread bleaching of corals or a collapse of oceanic circulation systems.
Climate variability - Climate variability refers to variations in the mean state and other statistics (such as standard deviations, statistics of extremes, etc.) of the climate on all temporal and spatial scales beyond that of individual weather events. Variability may be due to natural internal processes within the climate system (internal variability), or to variations in natural or human-induced external forcing (external variability). See also climate change.
Climate variation - See climate variability.
Cloud condensation nuclei - Cloud condensation nuclei or CCNs (also known as cloud seeds) are small particles (typically 1/100th the size of a cloud droplet) about which cloud droplets coalesce. See also aerosols.
Cloud radiative forcing - The impact of clouds on the irradiance at the top of the atmosphere.
CO2-equivalent or CO2-equivalent concentration - The concentration of carbon dioxide that would cause the same amount of radiative forcing as a given mixture of carbon dioxide and other heat-trapping gases (greenhouse gases).
Coastal squeeze - The squeeze of coastal ecosystems (e.g., salt marshes, mangroves and mud and sand flats) between rising sea levels and naturally or artificially fixed shorelines, including hard engineering defenses.
Co-benefits - The benefits of policies implemented for various reasons at the same time, acknowledging that most policies designed to address heat-trapping (greenhouse gas) mitigation have other, often at least equally important, rationales (e.g., related to objectives of development, sustainability, and equity). The term co-impact is also used in a more generic sense to cover both positive and negative side of the benefits. See also ancillary benefits.
Co-generation - The use of waste heat from thermal electricity-generation plants. The heat is e.g. condensing heat from steam turbines or hot flue gases exhausted from gas turbines, for industrial use, buildings or district heating. Synonym for Combined Heat and Power (CHP) generation.
Combined-cycle gas turbine (CCGT) - Power plant that combines two processes for generating electricity. First, gas or light fuel oil feeds a gas turbine that inevitably exhausts hot flue gases (>800°C or >1,472°F). Second, heat recovered from these gases, with additional firing, is the source for producing steam that drives a steam turbine. The turbines rotate separate alternators. It becomes an integrated CCGT when the fuel is syngas from a coal or biomass gasification reactor with exchange of energy flows between the gasification and CCGT plants.
Combined heat and power - See co-generation.
Committed to extinction - This term describes a species with dwindling population that is in the process of inescapably becoming extinct in the absence of human intervention. See also extinction.
Communicable disease - An infectious disease caused by transmission of an infective biological agent (virus, bacterium, protozoan, or multicellular macroparasite).
Conference of the parties (COP) - The supreme body of the UNFCCC, comprising countries with right to vote that have ratified or acceded to the convention. The first session of the Conference of the Parties (COP-1) was held in Berlin (1995).
Contingent valuation method (CVM) - CVM is an approach to quantitatively assess values assigned by people in monetary (willingness to pay) and non monetary (willingness to contribute with time, resources etc.) terms. It is a direct method to estimate economic values for ecosystem and environmental services. A survey of people are asked their willingness to pay for access to, or their willingness to accept compensation for removal of, a specific environmental service, based on a hypothetical scenario and description of the environmental service. See also values.
Control run - A model run carried out to provide a 'baseline' for comparison with climate-change experiments. The control run uses constant values for the radiative forcing due to heat-trapping gases (greenhouse gases) and human-induced aerosols appropriate to pre-industrial conditions.
Convection - Vertical motion driven by buoyancy forces arising from static instability, usually caused by near-surface cooling or increases in salinity in the case of the ocean and near-surface warming in the case of the atmosphere. At the location of convection, the horizontal scale is approximately the same as the vertical scale, as opposed to the large contrast between these scales in the general circulation. The net vertical mass transport is usually much smaller than the upward and downward exchange.
Coral - The term "coral" has several meanings, but is usually the common name for the Order Scleractinia, all members of which have hard limestone skeletons, and which are divided into reef-building and non-reef-building, or cold- and warm-water corals.
Coral bleaching - The paling in color which results if a coral loses its symbiotic, energy-providing, organisms.
Coral reefs - Rock-like limestone (calcium carbonate) structures built by corals along ocean coasts (fringing reefs) or on top of shallow, submerged banks or shelves (barrier reefs, atolls), most conspicuous in tropical and sub-tropical oceans.
Cost - The consumption of resources such as labor time, capital, materials, fuels and so on as the consequence of an action. In economics all resources are valued at their opportunity cost, being the value of the most valuable alternative use of the resources. Costs are defined in a variety of ways and under a variety of assumptions that affect their value ►Cost types include: ►administrative costs of planning, management, monitoring, audits, accounting, reporting, clerical activities, etc. associated with a project or program; ►damage costs to ecosystems, economies and people due to negative effects from climate change; ►implementation costs of changing existing rules and regulation, capacity building efforts, information, training and education, etc. to put a policy into place; ►private costs are carried by individuals, companies or other private entities that undertake the action, where ►social costs include additionally the external costs on the environment and on society as a whole. Costs can be expressed as total, average (unit, specific) being the total divided by the number of units of the item for which the cost is being assessed, and marginal or incremental costs as the cost of the last additional unit.
The perspectives adopted in the IPCC are: ►Project level considers a "standalone" activity that is assumed not to have significant indirect economic impacts on markets and prices (both demand and supply) beyond the activity itself. The activity can be the implementation of specific technical facilities, infrastructure, demand-side regulations, information efforts, technical standards, etc. ►Technology level considers a specific greenhouse-gas mitigation technology, usually with several applications in different projects and sectors. The literature on technologies covers their technical characteristics, especially evidence on learning curves as the technology diffuses and matures. ►Sector level considers sector policies in a "partial-equilibrium" context, for which other sectors and the macroeconomic variables are assumed to be as given. The policies can include economic instruments related to prices, taxes, trade, and financing, specific large-scale investment projects, and demand-side regulation efforts. ►Macroeconomic level considers the impacts of policies on real income and output, employment and economic welfare across all sectors and markets. The policies include all sorts of economic policies, such as taxes, subsidies, monetary policies, specific investment programs, and technology and innovation policies. The negative of costs are benefits, and often both are considered together.
Cost-benefit analysis - Monetary measurement of all negative and positive impacts associated with a given action. Costs and benefits are compared in terms of their difference and/or ratio as an indicator of how a given investment or other policy effort pays off seen from the society's point of view.
Cost-effectiveness analysis - A special case of cost-benefit analysis in which all the costs of a portfolio of projects are assessed in relation to a fixed policy goal. The policy goal in this case represents the benefits of the projects and all the other impacts are measured as costs or as negative costs (co-benefits). The policy goal can be, for example, a specified goal of emissions reductions of heat-trapping gases (greenhouse gases).
Glossaries of the contributions of Working Groups I, II and III to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report 2007.
Nakićenović, N., J. Alcamo, G. Davis, B. de Vries, J. Fenhann, S. Gaffin, K. Gregory, A. Grübler, T.Y. Jung, T. Kram, E.L. La Rovere, L. Michaelis, S. Mori, T. Morita, W. Pepper, H. Pitcher, L. Price, K. Raihi, A. Roehrl, H.-H. Rogner, A. Sankovski, M. Schlesinger, P. Shukla, S. Smith, R. Swart, S. van Rooijen, N. Victor and Z. Dadi, 2000: Emissions Scenarios: A Special Report of Working Group III of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, and New York, 599 pp.