Climate Change Glossary

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Adaptation: Adaptation to climate change refers to adjustment in natural or human systems in response to actual or expected climate change impacts. Responses to a changing climate can also include policies to minimize the predicted impacts of climate change (e.g., building better coastal defenses).

Additionality: When a project is additional, it can be built only because it receives money from selling carbon credits. When a dam is “non-additional,” it is being funded by sales from carbon credits even though it would have been built without revenues from those credits.

Baseline: The “baseline” defines the GHG emissions of activities that would have been implemented in the absence of a CDM project.

Baseline-and-Credit: A set of polluters that are not under an aggregate cap can create credits by reducing their emissions below a baseline level of emissions. These credits can be purchased by polluters that do have a regulatory limit.

Business-as-usual: The rate of greenhouse gas emissions, assuming no climate regulations.

Cap-and-Trade: Also known as emissions trading, C&T is when a government or international body sets a limit (i.e. the cap) on the amount of certain greenhouse gases that can be emitted. Companies (or countries) are given a certain amount of emission permits and are required to hold the same number of credits (or allowances). The total amount of allowances cannot exceed the cap.

A trade occurs when Company A finds that it is relatively cheaper or easier for them to reduce emissions below their required limit than Company B. Company A, which emits less than its allowance, is more efficient and can sell their extra permits to Company B, which has a harder time reducing their emissions. This creates a system that guarantees a set level of overall reductions, which can be lowered over time, while rewarding the most efficient companies and ensuring that the cap is met at the lowest possible economic cost.

Carbon credits: Credits represent the right to emit a specific amount of greenhouse gases. Credits can be exchanged between businesses or bought and sold in the international market at the current market price.

Carbon offsets: Instead of reducing their own emissions, a polluter can receive credit for supporting a project that either reduces emissions abroad or reduces emissions in an industry domestically that is not mandated to reduce emissions.

Certified Emissions Reductions (CER): A certified emission reduction or CER is a unit issued under the CDM that is equal to one metric ton of carbon dioxide equivalent, calculated using global warming potentials defined by the Kyoto Protocol.

Clean Development Mechanism (CDM): The CDM is an arrangement under the Kyoto Protocol that allows industrialized countries with a greenhouse gas reduction commitment (called Annex 1 countries) to invest in projects that reduce emissions in developing countries as an alternative to more expensive emission reductions in their own countries.

Climate change/global warming: Climate change is a change in global climate which results directly or indirectly from human activity that changes the composition of the global atmosphere and which is in addition to natural climate variability. Global warming is a more popular term that recognizes that global temperatures overall have been increasing since the Industrial Revolution.

Designated Operational Entities (DOE): An entity designated by the Kyoto Protocol Conference of the Parties, based on the recommendation by the Executive Board, as qualified to validate proposed CDM project activities as well as verify and certify reductions in anthropogenic emissions by sources of greenhouse gases (GHG) and net anthropogenic GHG removals by carbon sinks.

EU Emissions Trading Scheme (ETS): The ETS is the largest multi-national, emissions trading scheme in the world, and it forms a major pillar of EU climate policy. Under the ETS, large emitters of carbon dioxide within the EU must monitor and annually report their CO2 emissions, and they are obliged every year to return an amount of emission allowances to the government that is equivalent to their CO2 emissions in that year.

Fossil fuels: Fossil fuels or mineral fuels are fuel sources derived from fossils, or hydrocarbons found within the top layer of the Earth’s crust. Examples include coal, petroleum, and methane. Fossil fuels are non-renewable resources because they take millions of years to form, and fossil fuel reserves are being depleted much faster than new ones are being formed.

Greenhouse gas (GHG): gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and re-emit radiation from the sun at specific wavelengths within the spectrum of thermal infrared radiation emitted by the Earth’s surface, the atmosphere itself, and by clouds. Greenhouse gases are essential to maintaining a liveable temperature on Earth (which is why they are called “greenhouse” gases). Natural sources come from the Earth’s ecosystems, and anthropogenic sources include industrial, transportation, residential, commercial and agricultural processes.

In order, Earth’s most abundant greenhouse gases are: water vapor, carbon dioxide, methane, nitrous oxide, ozone, and CFCs. By effect, the most important greenhouse gases are: water vapor, which causes about 36-70% of the greenhouse effect on Earth; carbon dioxide, which causes 9-26%; methane, which causes 4-9%; and ozone, which causes 3-7%.

Henry’s Law: at a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.

Intergovernmental Panel on Climate Change (IPCC): A global scientific body tasked to evaluate the risk of climate change caused by human activity.

Joint Implementation (JI): defined in Article 6 of the Kyoto Protocol, allows a country with an emission reduction or limitation commitment under the Kyoto Protocol (Annex B countries, which are industrialized countries) to earn emission reduction units (ERUs) from an emission-reduction or emission removal project in another Annex B Party, each equivalent to one metric ton of CO2, which can be counted towards meeting its Kyoto target.

Kyoto Protocol: a protocol to the United Nations Framework Convention on Climate Change (UNFCCC or FCCC), an international environmental treaty produced at the United Nations Conference on Environment and Development (UNCED), informally known as the Earth Summit, held in Rio de Janeiro, Brazil, from 3-14 June 1992. The treaty is intended to achieve “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.” The Kyoto Protocol establishes legally binding commitments for the reduction of six greenhouse gases produced by “Annex I” (industrialized) nations, as well as general commitments for all member countries.

Linking Directive: the EU’s “Linking Directive” (2004) amends the Emissions Trading Directive (2003) and provides for the use of credits from the Kyoto Protocol’s two project mechanisms in the EU Emissions Trading Scheme–the Joint Implementation and the CDM.

Methane: a chemical compound with the molecular formula CH4. It is the principal component of natural gas. Burning methane in the presence of oxygen produces carbon dioxide and water. The relative abundance of methane and its clean burning process makes it a very attractive fuel. However, it has a global warming potential of 25 over a 100-year period. This means that a methane emission will have 25 times the impact on temperature of a carbon dioxide emission of the same mass over the following 100 years.

Mitigation: Intervention or policies to reduce the emissions or enhance the sinks of greenhouse gases. The current international legal mechanism for countries to reduce their emissions is the United Nations Framework Convention on Climate Change (UNFCCC).

Partial pressure: the pressure which a gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture.

Power density: power per unit of volume, an example of “specific power” (which is power per unit of mass, volume or area). An example is a heat engines , which can be characterized by its specific power, typically given in kilowatts per litre of engine displacement (or horsepower per cubic inch in the U.S.).

Project Design Document (PDD): A precise project description and serves as the basis for the CDM project evaluation by an Designated Operational Entity (DOE).

Rain-water harvesting: gathering, or accumulating and storing, of rainwater in either DIY systems (such as rain barrels) or commercial systems (used for irrigation or livestock). Traditionally, rainwater harvesting has been practiced in arid and semi-arid areas, and has provided drinking water, domestic water, water for livestock, water for small irrigation and a way to replenish ground water levels.

Renewable resource: a natural resource qualifies as a renewable resource if it is replenished by natural processes at a rate comparable or faster than its rate of consumption by humans or other users. Solar radiation, tides, and winds are perpetual resources that are in no danger of running out.

Reservoir emissions: Greenhouse gases, primarily methane (CH4) and carbon dioxide (CO2), that are emitted from the surface of a reservoir, at turbines and spillways, and for tens of kilometers downstream.

Run-of-river: type of hydroelectric generation, normally dependent on a dam, whereby the natural flow and elevation drop of a river are used to generate electricity. Power stations of this type are built on rivers with a consistent and steady flow, either natural or through the use of a large reservoir at the head of the river which then can provide a regulated steady flow for stations down-river. Run-of-river dams flood less land than storage dams but can have serious impacts on migratory fish and other aquatic and riverine species. Run-of-river projects with diversion structures can de-water long stretches of river. The distinction between run-of-river and storage dams is vague and some very large dams, such as Three Gorges Dam on the Yangtze, are sometimes described as run-of-river.

Sectoral crediting: A market mechanism, iike project-based crediting (as under the CDM), with a number of subtypes, where policies and/or investments leading to emission mitigation in a given sector could earn emission credits. 

World Commission on Dams: a global multi-stakeholder body initiated in 1997 by the World Bank and the World Conservation Union (IUCN) in response to growing opposition to large dam projects. The Commission had a mandate to review the development effectiveness of large dams and develop internationally acceptable guidelines for the planning, construction and operation of dams.

See the IPCC glossary (multiple languages), the CDM glossary, or Wikipedia for more definitions.