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[ A ]

Aerosols
Solid or liquid particles suspended in the atmosphere. Aerosols can result from natural sources such as volcanic ash and salt particles from sea spray, or from burning fossil fuels. Aerosols serve as nuclei for the condensation of water and ice, and as absorbers and scatterers of solar radiation influencing the radiation budget of the Earth’s climate system. Sulfate Aerosols reflect incoming light from the sun to offset some of the warming caused by greenhouse gases. Black Carbon Aerosols produced by inefficient combustion of fossil fuels absorb light from the sun and contribute to atmospheric warming.
Afforestation
Planting new forests in areas that have not been recently forested.
Air quality index
A measurement of the six major air pollutants particulates, sulfur dioxide (SO2), carbon monoxide (CO), nitrogen dioxide (NO2), lead (Pb), and ozone (O3). A measurement of 0 to 100 is considered acceptable; 100 to 150 is unhealthy for the elderly, young children, and people with asthma. Above 150 is unhealthy for everyone.
Allocation
As part of an emissions trading program, permits to emit are initially either grandfathered in for free based on past emissions in a base year or on an ‘updating’ approach based on more recent emissions. Alternatively, permits are auctioned in an initial market offering.
Alternative energy
Energy derived from nontraditional sources (e.g., compressed natural gas, solar, hydroelectric, wind).
Ancillary Benefits
Complementary benefits of a climate policy including improvements in local air quality and reduced reliance of imported fossil fuels.
Annex I Parties
Industrialized countries that, as parties to the Framework Convention on Climate Change, have pledged to reduce their greenhouse gas emissions by the year 2000 to 1990 levels. Annex I Parties consist of countries belonging to the Organization for Economic Cooperation and Development (OECD) and countries designated as Economies-in-Transition. The 40 countries plus the European Economic Community listed in Annex I of the UNFCCC are Australia, Austria, Belarus, Belgium, Bulgaria, Canada, Croatia, Czech Republic, Denmark, European Economic Community, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Japan, Latvia, Liechtenstein, Lithuania, Luxembourg, Monaco, The Netherlands, New Zealand, Norway, Poland, Portugal, Romania, Russian Federation, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, Ukraine, United States. (Also see Non-Annex parties)
Annex A
A list in the Kyoto Protocol of the six greenhouse gases and the sources of emissions covered under the Kyoto Protocol.
Annex B
A list in the Kyoto Protocol of 38 countries plus the European Community that agreed to QELRCs (emission targets), along with the QELRCs they accepted. The list is nearly identical to the Annex I Parties listed in the Convention except that it does not include Belarus or Turkey.
Atmosphere
The mixture of gases surrounding the Earth. It is made up of nearly 79% nitrogen, 21% oxygen, and small amounts of carbon dioxide and other gases. The atmosphere is divided into four layers, from the closest to the Earth to the farthest troposphere, stratosphere, mesosphere, and thermosphere.

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[ B ]

Baseline Emissions
The emissions that would occur without policy intervention (in a business-as-usual scenario). Baseline estimates are needed to determine the effectiveness of emissions reduction programs (often called mitigation strategies).
Base Year
Targets for reducing GHG emissions are often defined in relation to a base year. In the Kyoto Protocol, 1990 is the base year for most countries for the major GHGs; 1995 can be used as the base year for some of the minor GHGs.
Bioaccumulates
Substances taken into the body through contaminated food, water, or air that builds up slowly in body tissues or fat because they are slow to break down or be excreted.
Biodiversity
One word made from the two words biological and diversity, referring to the many types of plants and animals that live in a region. The more species, the greater the biodiversity.
Biofuel
Gas or liquid fuel made from plant material (biomass). Includes wood, wood waste, wood liquors, peat, railroad ties, wood sludge, spent sulfite liquors, agricultural waste, straw, tires, fish oils, tall oil, sludge waste, waste alcohol, municipal solid waste, landfill gases, other waste, and ethanol blended into motor gasoline.
Biomass
Total dry weight of all living organisms that can be supported at each tropic level in a food chain. Also, materials that are biological in origin, including organic material (both living and dead) from above and below ground, for example, trees, crops, grasses, tree litter, roots, and animals and animal waste.
Biomass energy
Energy produced by combusting biomass materials such as wood. The carbon dioxide emitted from burning biomass will not increase total atmospheric carbon dioxide if this consumption is done on a sustainable basis (i.e., if in a given period of time, regrowth of biomass takes up as much carbon dioxide as is released from biomass combustion). Biomass energy is often suggested as a replacement for fossil fuel combustion.
Biosphere
The living and dead organisms found near the earth’s surface in parts of the lithosphere, atmosphere, and hydrosphere. The part of the global carbon cycle that includes living organisms and biogenic organic matter.
Byrd-Hagel Resolution
In June 1997, anticipating the December 1997 meeting in Kyoto, Senator Robert C. Byrd (D-WV) introduced, with Sen. Chuck Hagel (R-NE) and 44 other cosponsors, a resolution stating that the impending Kyoto Protocol (or any subsequent international climate change agreement) should not – “(A) mandate new commitments to limit or reduce GHG emissions for the Annex I Parties [i.e. industrialized countries], unless the protocol or other agreement also mandates new specific scheduled commitments to limit or reduce GHG emissions for Developing Country Parties within the same compliance period, or (B) would result in serious harm to the economy of the United States…”

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[ C ]

Carbon cycle
All carbon reservoirs and exchanges of carbon from reservoir to reservoir by various chemical, physical, geological, and biological processes. Usually thought of as a series of the four main reservoirs of carbon interconnected by pathways of exchange. The four reservoirs, regions of the Earth in which carbon behaves in a systematic manner, are the atmosphere, terrestrial biosphere (usually includes freshwater systems), oceans, and sediments (includes fossil fuels). Each of these global reservoirs may be subdivided into smaller pools, ranging in size from individual communities or ecosystems to the total of all living organisms (biota).
Carbon dioxide (CO2)
A colorless, odorless, gas that is a normal part of the ambient air. Humans exhale it, and trees and other plants absorb it and use it to make food. Cutting down trees or burning fossil fuels, such as oil and coal, increases carbon dioxide in the atmosphere. Although carbon dioxide does not directly impair human health, it is a greenhouse gas that traps terrestrial (i.e., infrared) radiation and contributes to the potential for global warming. Of the six greenhouse gases normally targeted, CO2 contributes the most to human-induced global warming. Human activities such as fossil fuel combustion and deforestation have increased atmospheric concentrations of CO2 by approximately 30 percent since the industrial revolution. CO2 is the standard used to determine the “global warming potentials” (GWPs) of other gases. CO2 has been assigned a 100-year GWP of 1 (i.e., the warming effects over a 100-year time frame relative to other gases).
Carbon dioxide equivalent (CO2e)
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).” 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)

Carbon monoxide
A colorless, odorless, poisonous gas (chemical symbol CO) released into the air when organic
materials, such as oil, coal, and wood, are burned. The more that oxygen is restricted during the burning process, the more carbon monoxide will be created.
Carbon Sinks
Carbon reservoirs and conditions that take-in and store more carbon (i.e., carbon sequestration) than they release. Carbon sinks can serve to partially offset greenhouse gas emissions. Forests and oceans are large carbon sinks.
Carbon intensity
The relative amount of carbon emitted per unit of energy or fuels consumed.
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.
Carbon Taxes
A surcharge on the carbon content of oil, coal, and gas that discourages the use of fossil fuels and aims to reduce carbon dioxide emissions.
Certified Emissions Reduction (CER)
Reductions of greenhouse gases achieved by a Certified Development Mechanism (CDM) project. A CER can be sold or counted toward Annex I countries’ emissions commitments. Reductions must be additional to any that would otherwise occur.
Chlorofluorocarbons (CFCs)
CFCs are synthetic industrial gases composed of chlorine, fluorine, and carbon. They have been used as refrigerants, aerosol propellants, cleaning solvents and in the manufacture of plastic foam. One chlorine atom from a CFC can destroy more than 100,000 ozone molecules. A leaky air conditioner that uses CFCs can destroy millions of ozone molecules. There are no natural sources of CFCs. CFCs have an atmospheric lifetime of decades to centuries, and they have 100-year “global warming potentials” thousands of times that of CO2, depending on the gas. In addition to being greenhouse gases, CFCs also contribute to ozone depletion in the stratosphere and are controlled under the Montreal Protocol.
Clean Development Mechanism (CDM)
One of the three market mechanisms established by the Kyoto Protocol. The CDM is designed to promote sustainable development in developing countries and assist Annex I Parties in meeting their greenhouse gas emission reduction commitments. It enables industrialized countries to invest in emission reduction projects in developing countries and to receive credits for reductions achieved.
Climate
Climate is the expected long-term weather found in a region, such as a hot, dry desert or the cold, snowy arctic. 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 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 hailstorms, and other measures of the weather.
Climate change
Often called global warming, climate change refers to long-term trends in the average climate, such as changes in average temperatures. In IPCC usage, climate change refers to any change in climate over time, whether due to natural variability or as a result of human activity. In UNFCCC usage, climate change refers to a change in climate that is attributable directly or indirectly to human activity that alters atmospheric composition.
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.
Climate sensitivity
The average global air surface temperature change resulting from a doubling of pre-industrial atmospheric CO2 concentrations. The IPCC estimates climate sensitivity at 1.5-4.5oC (2.7-8.1oF).
Climate Variability
Refers to changes in patterns, such as precipitation patterns, in the weather and climate.
Closed system
Earth is a closed system in which no matter or energy can leave or enter from the outside. Water and energy can be changed from one form to another, but none can be created nor destroyed. The resources that are on Earth now are all that we will ever have, so taking good care of them is important.
Coal
A black or brownish black solid, combustible substance formed by the partial decomposition of vegetable matter without access to air. The rank of coal, which includes anthracite, bituminous coal, subbituminous coal, and lignite, is based on fixed carbon, volatile matter, and heating value. Coal rank indicates the progressive alteration, or coalification, from lignite to anthracite.
Coal coke
A hard, porous product made from baking bituminous coal in ovens at temperatures as high as 2,000 degrees Fahrenheit. It is used both as a fuel and as a reducing agent in smelting iron ore in a blast furnace.
Coal gasification
Conversion of solid coal to synthetic natural gas (SNG) or a gaseous mixture that can be burned as a fuel.
Coal liquefaction
Conversion of solid coal to a liquid fuel such as synthetic crude oil or methanol.
Coalbed methane
Methane that is produced from coalbeds in the same manner as natural gas produced from other strata. Methane is the principal component of natural gas.
Co-control benefit
The additional benefit derived from an environmental policy that is designed to control one type of pollution, while reducing the emissions of other pollutants as well. For example, a policy to reduce carbon dioxide emissions might reduce the combustion of coal, but when coal combustion is reduced, so too are the emissions of particulates and sulfur dioxide. The benefits associated with reductions in emissions of particulates and sulfur dioxide are the co-control benefits of reductions in carbon dioxide.
Cogeneration
Production of two useful forms of energy such as high-temperature heat and electricity from the same process. For example, while boiling water to generate electricity, the leftover steam can be sold for industrial processes or space heating.
Commitment Period
The period under the Kyoto Protocol during which Annex I Parties’ GHG emissions, averaged over the period, must be within their emission targets. The first commitment period runs from January 1, 2008 to December 31, 2012.
Conservation tillage
A land cultivation method used to prepare soil for planting. It leaves some plant residues on the soil surface for erosion control and moisture conservation, instead of plowing them into the soil.
Contaminated
Refers to air, water, soil, or food that has been polluted by dangerous chemicals or infectious microbes (viruses, bacteria, or parasites) so that it becomes unusable or harmful. These contaminants may be physical, chemical, biological, or radiological substances.
Coral reef
Rock-like structures built by corals. Corals are small (inch-long) ocean animals. Young corals attach themselves to the limestone skeletons of dead corals. Over thousands and millions of years, layers of skeletons build up and grow into reefs. Reefs are home to a quarter of all ocean species. Called the rain forests of the sea, coral reefs are endangered.
Crude oil
A mixture of hydrocarbons that exist in liquid phase in underground reservoirs and remain liquid at atmospheric pressure after passing through surface separating facilities.
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.

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[ D ]

Deforestation
Destruction of forests, either by logging or burning down trees to make land for agriculture. Since trees provide oxygen and absorb carbon dioxide, destruction of forests affects the atmosphere and is often seen as a major cause of enhanced greenhouse effect. Deforestation also destroys animal habitats.
Desertification
The change from once fertile land into desert. Causes include overgrazing by animals, deforestation, drought, the burning of large areas of forest or other vegetation to make farmland, and the overuse of water for irrigation. Once formed, deserts can only support a sparse range of vegetation. Climatic effects associated with this phenomenon include increased albedo, reduced atmospheric humidity, and greater atmospheric dust (aerosol) loading.
Developing
Describes regions and countries that are still in the process of acquiring modern technology and becoming economically productive. These regions are sometimes called the “Third World.”

Dioxin
Toxic, human-made chemical byproducts (dibenzo-p-dioxins), released into the atmosphere from incineration and during industrial processes that use chlorine. Dioxin tends to accumulate in the fatty tissue of fish. They can have immediate and long-term health effects, including skin disease, cancer, and reproductive failure.
Droughts
A lack of precipitation over a long period of time, usually for a season or more. Too little water results in water shortages, which can affect people’s ability to grow food and have enough clean, safe water. In extreme cases, it can lead to famine and malnutrition.

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[ E ]

Early Crediting
A provision that allows crediting of emission reductions achieved prior to the start of a legally imposed emission control period. These credits can then be used to assist in achieving compliance once a legally imposed system begins.
Ecology
The study of the relationship of living organisms with each other and with their surroundings.
Ecosystem
A community of plants and animals living in an area along with the things they need to sustain life, such as a place to live, food, and water. An ecosystem can be as small as a tiny tide pool or as large as a vast desert. Ecosystems have no fixed boundaries; instead their parameters are set to the scientific, management, or policy question being examined. Depending upon the purpose of analysis, a single lake, a watershed, or an entire region could be considered an ecosystem.
El Niño
A climatic phenomenon occurring irregularly, but generally every 3 to 5 years. El Niños often first become evident during the Christmas season (El Niño means Christ child) in the surface oceans of the eastern tropical Pacific Ocean. The phenomenon involves seasonal changes in the direction of the tropical winds over the Pacific and abnormally warm surface ocean temperatures. The changes in the tropics are most intense in the Pacific region; these changes can disrupt weather patterns throughout the tropics and can extend to higher latitudes, especially in Central and North America. The relationship between these events and global weather patterns are currently the subject of much research in order to enhance prediction of seasonal to interannual fluctuations in the climate.
Emission inventory
A list of air pollutants emitted into a community’s, state’s, nation’s, or the Earth’s atmosphere in amounts per some unit time (e.g. day or year) by type of source. An emission inventory has both political and scientific applications.
Emissions
The release of a substance (usually a gas when referring to the subject of climate change) into the atmosphere.
Emissions coefficient/factor
A unique value for scaling emissions to activity data in terms of a standard rate of emissions per unit of activity (e.g., grams of carbon dioxide emitted per barrel of fossil fuel consumed).
Emissions Cap
A mandated restraint in a scheduled time frame that puts a “ceiling” on the total amount of anthropogenic greenhouse gas emissions that can be released into the atmosphere. This can be measured as gross emissions or as net emissions (emissions minus gases that are sequestered).
Emissions Reduction Unit (ERU)
Emissions reductions generated by projects in Annex B countries that can be used by another Annex B country to help meet its commitments under the Kyoto Protocol. Reductions must be additional to those that would otherwise occur.
Emissions Trading
A market mechanism that allows emitters (countries, companies or facilities) to buy emissions from or sell emissions to other emitters. Emissions trading is expected to bring down the costs of meeting emission targets by allowing those who can achieve reductions less expensively to sell excess reductions (e.g. reductions in excess of those required under some regulation) to those for whom achieving reductions is more costly.
Energy
The capacity for doing work as measured by the capability of doing work (potential energy) or the conversion of this capability to motion (kinetic energy). Energy has several forms, some of which are easily convertible and can be changed to another form useful for work. Most of the world’s convertible energy comes from fossil fuels that are burned to produce heat that is then used as a transfer medium to mechanical or other means in order to accomplish tasks. In the United States, electrical energy is often measured in kilowatt-hours (kWh), while heat energy is often measured in British thermal units (Btu).
Energy conservation
Reduction or elimination of unnecessary energy use and waste.
Energy-efficiency
The ratio of the useful output of services from an article of industrial equipment to the energy use by such an article; for example, vehicle miles traveled per gallon of fuel (mpg).
Energy inputs
The amount of energy used to produce a product.
Energy intensity
Ratio between the consumption of energy to a given quantity of output; usually refers to the amount of primary or final energy consumed per unit of gross domestic product.
Energy quality
Ability of a form of energy to do useful work. High-temperature heat and the chemical energy in fossil fuels and nuclear fuels are concentrated high quality energy. Low-quality energy such as low-temperature heat is dispersed or diluted and cannot do much useful work.
Energy Resources
The available supply and price of fossil and alternative resources will play a huge role in estimating how much a greenhouse gas constraint will cost. In the U.S. context, natural gas supply (and thus price) is particularly important, as it is expected to be a transition fuel to a lower carbon economy.
Enhanced Greenhouse Effect
The increase in the natural greenhouse effect resulting from increases in atmospheric concentrations of GHGs due to emissions from human activities. The concept that the natural greenhouse effect has been enhanced by anthropogenic emissions of greenhouse gases. Increased concentrations of carbon dioxide, methane, and nitrous oxide, CFCs, HFCs, PFCs, SF6, NF3 and other photochemically important gases caused by human activities such as fossil fuel consumption, trap more infra-red radiation, thereby exerting a warming influence on the climate.
Ethanol (C2H5OH)
Otherwise known as ethyl alcohol, alcohol, or grain spirit. A clear, colorless, flammable oxygenated hydrocarbon with a boiling point of 78.5 degrees Celsius in the anhydrous state. In transportation, ethanol is used as a vehicle fuel by itself (E100), blended with gasoline (E85), or as a gasoline octane enhancer and oxygenate (10 percent concentration).
Exponential growth
Growth in which some quantity, such as population size, increases by a constant percentage of the whole during each year or other time period; when the increase in quantity over time is plotted, this type of growth yields a curve shaped like the letter J.

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[ F ]

Feedlot
Confined outdoor or indoor space used to raise hundreds to thousands of domesticated livestock. Animals are completely dependent on an outside source for food. The large concentrations of animal waste that accumulate cannot be absorbed by the soil and often end up carried into nearby streams or lakes by rainfall runoff.
Fluidized bed combustion (FBC)
Process for burning coal more efficiently, cleanly, and cheaply. A stream of hot air is used to suspend a mixture of powdered coal and limestone during combustion. About 90 to 98 percent of the sulfur dioxide produced during combustion is removed by reaction with limestone to produce solid calcium sulfate.
Fluorocarbons
Carbon-fluorine compounds that often contain other elements such as hydrogen, chlorine, or bromine. Common fluorocarbons include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs).
Forcing Mechanism
A process that alters the energy balance of the climate system, i.e. changes the relative balance between incoming solar radiation and outgoing infrared radiation from Earth. Such mechanisms include changes in solar irradiance, volcanic eruptions, and enhancement of the natural greenhouse effect by emission of carbon dioxide.
Fossil fuel
Buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil, coal, natural gas, or heavy oils by exposure to heat and pressure in the earth’s crust over hundreds of millions of years. When burned, they are a leading cause of greenhouse gases and global warming.
Fossil fuel combustion
Burning of coal, oil (including gasoline), or natural gas. This burning, usually to generate energy, releases carbon dioxide, as well as combustion by products that can include unburned hydrocarbons, methane, and carbon monoxide. Carbon monoxide, methane, and many of the unburned hydrocarbons slowly oxidize into carbon dioxide in the atmosphere. Common sources of fossil fuel combustion include cars and electric utilities.
Fugitive emissions
Unintended gas leaks from the processing, transmission, and/or transportation of fossil fuels, CFCs from refrigeration leaks, SF6 from electrical power distributor, etc.

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[ G ]

Gasohol
Vehicle fuel consisting of a mixture of gasoline and ethyl or methyl alcohol; typically 10 to 23 percent ethanol by volume.
GDP
Gross Domestic Product, a measure of overall economic activity.General Circulation Model

(GCM)
A global, three-dimensional computer model of the climate system which can be used to simulate human-induced climate change. GCMs are highly complex and they represent the effects of such factors as reflective and absorptive properties of atmospheric water vapor, greenhouse gas concentrations, clouds, annual and daily solar heating, ocean temperatures and ice boundaries. The most recent GCMs include global representations of the atmosphere, oceans, and land surface.
Geothermal energy
Heat transferred from the earth’s molten core to under-ground 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.
Glaciers
A large body of ice that forms through the tight packing and freezing of snow and then advances and recedes slowly due to its enormous weight and the pull of gravity, changing the shape of the land as it moves.
Global surface temperature
Average temperature of the Earth’s surface. This chart from NASA shows the change in the global average surface temperature since 1880.
Global warming
Also called climate change, the progressive gradual rise of the earth’s surface temperature thought to be caused by the greenhouse effect and responsible for changes in global climate patterns. An increase in the near surface temperature of the Earth. Global warming has occurred in the distant past as the result of natural influences, but the term is most often used to refer to the warming predicted to occur as a result of increased emissions of greenhouse gases.
Global Warming Potential (GWP)
The index used to translate the level of emissions of various gases into a common measure in order to compare the relative radiative forcing of different gases without directly calculating the changes in atmospheric concentrations. GWPs are calculated as the ratio of the radiative forcing that would result from the emissions of one kilogram of a greenhouse gas to that from emission of one kilogram of carbon dioxide over a period of time (usually 100 years).
Greenhouse effect
The effect produced as greenhouse gases allow incoming solar radiation to pass through the Earth’s atmosphere, but prevent part of the outgoing infrared radiation from the Earth’s surface and lower atmosphere from escaping into outer space. This process occurs naturally and has kept the Earth’s temperature about 59 degrees F warmer than it would otherwise be. Current life on Earth could not be sustained without the natural greenhouse effect.
Greenhouse Gas
Any gas that absorbs infrared radiation in the atmosphere. Greenhouse gases include water vapor, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), halogenated fluorocarbons (HCFCs), ozone (O3), perfluorinated carbons (PFCs), and hydrofluorocarbons (HFCs).

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[ H ]

Habitat fragmentation
The breaking up of spaces that are home to animals into smaller and unconnected segments (due, for example, to a subdivision being built in the middle of a forest, a road through a meadow, or a dam across a river). This can result in the loss of habitat as well as the disruption of an ecosystem.
Halocarbons
Chemicals consisting of carbon, sometimes hydrogen, and either chlorine, fluorine bromine or iodine.
Halons
Compounds, also known as bromofluorocarbons, that contain bromine, fluorine, and carbon. They are generally used as fire extinguishing agents and cause ozone depletion. Bromine is many times more effective at destroying stratospheric ozone than chlorine.
HGWP (High Global Warming Potential)
Some industrially produced gases such as sulfur hexafluoride (SF6), perfluorocarbons (PFCs), and hydrofluorocarbons (HFCs) have extremely high GWPs. Emissions of these gases have a much greater effect on global warming than an equal emission (by weight) of the naturally occurring gases. Most of these gases have GWPs of 1,300 – 23,900 times that of CO2. These GWPs can be compared to the GWPs of CO2, CH4, and N2O which are presently estimated to be 1, 23 and 296, respectively.
“Hot Air”
A situation in which emissions (of a country, sector, company or facility) are well below a target due to the target being above emissions that materialized under the normal course of events (i.e., without deliberate emission reduction efforts). Hot air can result from over-optimistic projections of growth. Emissions are often projected to grow roughly in proportion to GDP, and GDP is often projected to grow at historic rates. If a recession occurs and fuel use declines, emissions may be well below targets since targets are generally set in relation to emission projections. If emission trading is allowed, an emitter could sell the difference between actual emissions and emission targets. Such emissions are considered hot air because they do not represent reductions from what would have occurred in the normal course of events.
Hydrocarbons
Chemicals formed from hydrogen and carbon. Fossil fuels such as natural gas and oil are made up of these compounds. These fuels provide heat (in buildings), light, and power (used in cars and in plants that generate electricity). When burned, hydrocarbons release pollutants into the atmosphere.
Hydrochlorofluorocarbons (HCFCs)
Compounds containing hydrogen, fluorine, chlorine, and carbon atoms. Although ozone depleting substances, they are less potent at destroying stratospheric ozone than chlorofluorocarbons (CFCs). They have been introduced as temporary replacements for CFCs and are also greenhouse gases.
Hydroelectric power plant
Structure in which the energy of fading or flowing water spins a turbine generator to produce electricity.
Hydrofluorocarbons (HFCs)
HFCs are synthetic industrial gases, primarily used in refrigeration and semi-conductor manufacturing as commercial substitutes for chlorofluorocarbons (CFCs). There are no natural sources of HFCs. The atmospheric lifetime of HFCs is decades to centuries, and they have 100-year “global warming potentials” thousands of times that of CO2, depending on the gas. HFCs are among the six greenhouse gases to be curbed under the Kyoto Protocol.
Hydropower
Electrical energy produced by falling or flowing water.

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[ I ]

Ice core
A cylindrical section of ice removed from a glacier or an ice sheet in order to study climate patterns of the past. By performing chemical analyses on the air trapped in the ice, scientists can estimate the percentage of carbon dioxide and other trace gases in the atmosphere at that time.
Incentive-based Regulation
A regulation that uses the economic behavior of firms and households to attain desired environmental goals. Incentive-based programs involve taxes on emissions or tradable emission permits. The primary strength of incentive-based regulation is the flexibility it provides the polluter to find the least costly way to reduce emissions.
Industrial revolution
A dramatic change in the ways people earned money and made goods that began in England around the mid-1800s. People went from making goods in their own homes with simple tools to making them in large-scale factories with complicated machinery. As a result, many rural regions became more urban as cities grew rapidly around the new industrial activity.
Industrial sector
Construction, manufacturing, agricultural and mining establishments.
Intergovernmental Panel on Climate Change (IPCC)
The IPCC was established jointly by the United Nations Environment Programme and the World Meteorological Organization in 1988. The purpose of the IPCC is to assess information in the scientific and technical literature related to all significant components of the issue of climate change. The IPCC draws upon hundreds of the world’s expert scientists as authors and thousands as expert reviewers. Leading experts on climate change and environmental, social, and economic sciences from some 60 nations have helped the IPCC to prepare periodic assessments of the scientific underpinnings for understanding global climate change and its consequences. With its capacity for reporting on climate change, its consequences, and the viability of adaptation and mitigation measures, the IPCC is also looked to as the official advisory body to the world’s governments on the state of the science of the climate change issue. For example, the IPCC organized the development of internationally accepted methods for conducting national greenhouse gas emission inventories.
Irreversibilities
Changes that, once set in motion, cannot be reversed, at least on human time scales.

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[ J ]

Jet fuel
Includes both naphtha-type and kerosene-type fuels meeting standards for use in aircraft turbine engines. Although most jet fuel is used in aircraft, some is used for other purposes such as generating electricity.
Joint implementation (JI)
Agreements made between two or more nations under the auspices of the United Nations Framework Convention on Climate Change to help reduce greenhouse gas emissions. One of the three market mechanisms established by the Kyoto Protocol. Joint Implementation occurs when an Annex B country invests in an emissions reduction or sink enhancement project in another Annex B country to earn emission reduction units (ERUs).

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[ K ]

Kerogen
Solid, waxy mixture of rock is heated to high temperatures, the kerogen is vaporized. The vapor is condensed and then sent to a refinery to produce gasoline, heating oil, and other products.

Kerosene
A petroleum distillate that has a maximum distillation temperature of 401 degrees Fahrenheit at the 10 percent recovery point, a final boiling point of 572 degrees Fahrenheit, and a minimum flash point of 100 degrees Fahrenheit. Used in space heaters, cook stoves, and water heaters, and suitable for use as an illuminant when burned in wick lamps.
Kyoto Mechanisms
The Kyoto Protocol creates three market-based mechanisms that have the potential to help countries reduce the cost of meeting their emissions reduction targets. These mechanisms are Joint Implementation (Article 6), the Clean Development Mechanisms (Article 12), and Emissions Trading (Article 17).
Kyoto Protocol
This is 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, individual countries have committed to reduce their greenhouse gas emissions by a specified amount.

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[ L ]

Land Use, Land-Use Change and Forestry (LULUCF)
Land uses and land-use changes can act either as sinks or as emission sources. It is estimated that approximately one-fifth of global emissions result from LULUCF activities. The Kyoto Protocol allows Parties to receive emissions credit for certain LULUCF activities that reduce net emissions.
Landfill
Land waste disposal site in which waste is generally spread in thin layers, compacted, and covered with a fresh layer of soil each day. Landfills produce methane, which can be captured for electricity generation or flared.
Lifetime (Atmospheric)
The lifetime of a greenhouse gas refers to the approximate amount of time it would take for the anthropogenic increment to an atmospheric pollutant concentration to return to its natural level (assuming emissions cease) as a result of either being converted to another chemical compound or being taken out of the atmosphere via a sink. This time depends on the pollutant’s sources and sinks as well as its reactivity. The lifetime of a pollutant is often considered in conjunction with the mixing of pollutants in the atmosphere; a long lifetime will allow the pollutant to mix throughout the atmosphere. Average lifetimes can vary from about a week (sulfate aerosols) to more than a century (CFCs, carbon dioxide).
Light-duty vehicles
Automobiles and light trucks combined.
Liquefied natural gas (LNG)
Natural gas converted to liquid form by cooling to a very low temperature.
Liquefied petroleum gas (LPG)
Ethane, ethylene, propane, propylene, normal butane, butylene, and isobutane produced at refineries or natural gas processing plants, including plants that fractionate new natural gas plant liquids.
Low Emission Vehicle (LEV)
A vehicle meeting the low-emission vehicle standards.

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[ M ]

Market Benefits
Benefits of a climate policy that can be measured in terms of avoided market impacts such as changes in resource productivity (e.g., lower agricultural yields, scarcer water resources) and damages to human-built environment (e.g., coastal flooding due to sea-level rise).
Mauna Loa Record
The record of measurement of atmospheric CO2 concentrations taken at Mauna Loa Observatory, Mauna Loa, Hawaii, since March 1958. This record shows the continuing increase in average annual atmospheric CO2 concentrations.
Methane (CH4)
CH4 is among the six greenhouse gases to be curbed under the Kyoto Protocol. A hydrocarbon that is a greenhouse gas with a global warming potential most recently estimated at 21. Methane is produced through anaerobic (without oxygen) decomposition of waste in landfills, animal digestion, decomposition of animal wastes, production and distribution of natural gas and petroleum, coal production, and incomplete fossil fuel combustion. The atmospheric concentration of methane as been shown to be increasing at a rate of about 0.6 percent per year and the concentration of about 1.7 per million by volume (ppmv) is more than twice its pre-industrial value. However, the rate of increase of methane in the atmosphere may be stabilizing.
Methanol (CH33OH)
A colorless poisonous liquid with essentially no odor and little taste. It is the simplest alcohol with a boiling point of 64.7 degrees Celsius. In transportation, methanol is used as a vehicle fuel by itself (M100), or blended with gasoline (M85).
Methanotrophic
Having the biological capacity to oxidize methane to CO2 and water by metabolism under aerobic conditions.
Metric Ton
Common international measurement for the quantity of greenhouse gas emissions. A metric ton is equal to 2205 lbs or 1.1 short tons.
Model year
Refers to the “sales” model year; for example, vehicles sold during the period from October 1 to the next September 31 is considered one model year.
Molecule
Chemical combination of two or more atoms of the same chemical element (such as O2) or different chemical elements (such as H2O).
Montreal Protocol on Substances that Deplete the Ozone Layer
The Montreal Protocol was signed in Montreal, Canada, by over 150 countries at a convention in 1987 to cut use of CFCs (chlorofluorocarbons). The aim of the Protocol was to protect the ozone layer in the stratosphere by decreasing and eventually eliminating the use of ozone-depleting substances like CFCs. It is regarded as one of the most successful international treaties in modern history. Under the Protocol, several international organizations report on the science of ozone depletion, implement projects to help move away from ozone depleting substances, and provide a forum for policy discussions. In the United States, the Protocol is implemented under the Clean Air Act Amendments of 1990.
Motor gasoline
A complex mixture of relatively volatile hydrocarbons, with or without small quantities of additives, obtained by blending appropriate refinery streams to form a fuel suitable for use in spark-ignition engines. Motor gasoline includes both leaded and unleaded grades of finished gasoline, blending components, and gasohol.
Mount Pinatubo
A volcano in the Philippine Islands that erupted in 1991. The eruption of Mount Pinatubo ejected enough particulate and sulfate aerosol matter into the atmosphere to block some of the incoming solar radiation from reaching Earth’s atmosphere. This effectively cooled the planet from 1992 to 1994, masking the warming that had been occurring for most of the 1980s and 1990s.

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[ N ]

National Action Plans
Plans submitted to the Conference of the Parties (COP) by all Parties outlining the steps that they have adopted to limit their anthropogenic GHG emissions. Countries must submit these plans as a condition of participating in the UN Framework Convention on Climate Change and, subsequently, must communicate their progress to the COP regularly.
Natural gas liquids (NGLs)
Those hydrocarbons in natural gas that are separated as liquids from the gas. Includes natural gas plant liquids and lease condensate.
Natural gas
Underground deposits of gases consisting of 50 to 90 percent methane (CH4) and small amounts of heavier gaseous hydrocarbon compounds such as propane (C3H8) and butane (C4H10).
Natural resources
Nature’s gifts; natural materials essential to humans, such as water, air, land, trees, animals, plants, soil, and minerals. Some are replaceable; others are not. Trees and fish are renewable resources and can be replaced. Nonrenewable resources, such as water and natural gas are not replaceable once they have been used.
Negative Feedback
A process that results in a reduction in the response of a system to an external influence. For example, increased plant productivity in response to global warming would be a negative feedback on warming, because the additional growth would act as a sink for CO2, reducing the atmospheric CO2 concentration.
New urbanism
A movement to promote cities and towns with planned growth that minimizes damage to the environment.
Nitrogen cycle
Cyclic movement of nitrogen in different chemical forms from the environment, to organisms, and then back to the environment.
Nitrogen dioxide
A pollutant that causes smog and acid rain, as well as eye, throat, and lung irritation. Nitrogen dioxide (chemical symbol NO2) is mainly produced by burning fossil fuels (e.g., emissions from burning gasoline in a car).
Nitrogen fixation
Conversion of atmospheric nitrogen gas into forms useful to plants and other organisms by lightning, bacteria, and blue-green algae; it is part of the nitrogen cycle.
Nitrogen oxides (NOx)
Chemical compounds made up of nitrogen (N) and oxygen (O). These elements are found in the atmosphere naturally. As a result of burning fossil fuels, these elements combine into pollutants such as nitrogen dioxide (one atom of N and two of O) and nitrogen trioxide (one of N and three of O). Nitrogen oxides are a major component of acid rain and contributor to global warming. About 95 percent of the increased levels of nitrogen oxides found in our atmosphere today come from humans burning fossil fuels. The rest comes from natural sources such as volcanoes and the action of bacteria in soil.
Nitrogen
A chemical element (N) that occurs in nature as a gas and makes up nearly 79% of the Earth’s atmosphere.
Nitrous Oxide (N2O)
A powerful greenhouse gas with a global warming potential most recently evaluated at 310. Major sources of nitrous oxide include soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning.
Nobel Prize
An international award given every year, since 1901, recognizing achievements in literature, economics, physics, chemistry, medicine, and peace.
Non-Annex B Parties
Countries that are not listed in Annex B of the Kyoto Protocol. (See also, Annex Parties)
Non-Annex I Parties
Countries that have ratified or acceded to the UNFCCC that are not listed in Annex I of the UNFCCC.
Nonlinearities
Occur when changes in one variable cause a more than proportionate impact on another variable.
Non-Market Benefits
Benefits of a climate policy that can be measured in terms of avoided non-market impacts such as human-health impacts (e.g., increased incidence of tropical diseases) and damages to ecosystems (e.g., loss of biodiversity).
Non-methane volatile organic compounds (NMVOCs)
Organic compounds, other than methane, that participate in atmospheric photochemical reactions.
Non-Party
A state that has not ratified the UNFCCC. Non-parties may attend talks as observers.
No-till farming
Planting crops without using machines to plow or turn over the soil. This practice minimizes soil loss and creates more fertile soil due to the residues left from each previous crop harvest. It is a vital part of sustainable agriculture. No-till and low-till methods are types of conservation tillage.
Nuclear electric power
Electricity generated by an electric power plant whose turbines are driven by steam generated in a reactor by heat from the fissioning of nuclear fuel.
Nuclear energy
Energy released when atomic nuclei undergo a nuclear reaction such as the spontaneous emission of radioactivity, nuclear fission, or nuclear fusion.

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[ O ]

Oil shale
Underground formation of a fine-grained sedimentary rock containing varying amounts of kerogen, a solid, waxy mixture of hydrocarbon compounds. Heating the rock to high temperatures converts the kerogen to a vapor, which can be condensed to form a slow flowing heavy oil called shale oil.
Oxygen cycle
Cyclic movement of oxygen in different chemical forms from the environment, to organisms, and then back to the environment.
Oxygen
A gaseous element (chemical symbol O) that is essential for life. Most animals need it both to breathe and to create energy from their food. It is also necessary for materials such as wood and coal to burn.
Ozone (O3)
A colorless gas with a pungent odor, having the molecular form of O3 , found in two layers of the atmosphere, the stratosphere (about 90% of the total atmospheric loading) and the troposphere (about 10%). Ozone is a form of oxygen found naturally in the stratosphere that provides a protective layer shielding the Earth from ultraviolet radiation’s harmful health effects on humans and the environment. In the troposphere, ozone is a chemical oxidant and major component of photochemical smog. Ozone can seriously affect the human respiratory system.
Ozone depleting substances
A family of man made compounds that includes, but are not limited to, cholorofluorocarbons (CFCs) bromofluorocarbons (halons), methyl chloroform, carbon tetrachloride, methyl bromide, and hydrochloroflurocarbons(HCFCs). These compounds have been shown to deplete stratospheric ozone, and therefore are typically referred to as ODSs.

Ozone layer

Lies approximately 15-40 kilometers (10-25 miles) above the Earth’s surface in the stratosphere. It protects the Earth from receiving harmful rays from the sun. Depletion or thinning of this layer leads to an increased number of skin cancers, eye problems, and other health concerns.
Ozone precursors
Chemical compounds, such as carbon monoxide, methane, non-methane hydrocarbons, and nitrogen oxides, which in the presence of solar radiation react with other chemical compounds to form ozone, mainly in the troposphere.

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[ P ]

Particulate matter (PM)
Solid particles or liquid droplets suspended or carried in the air (e.g., soot, dust, fumes, mist).
Particulates
Solids or liquids from smoke, dust, or other substances that can hang in the air and remain as separate particles for long periods of time. These are often the result of burning gas, wood, and other fuels. The smallest particulates can be inhaled and cause serious breathing problems, especially for children, people with asthma, and the elderly.
Parts per billion (ppb)
Number of parts of a chemical found in one billion parts of a particular gas, liquid, or solid mixture.
Parts per million (ppm)
Number of parts of a chemical found in one million parts of a particular gas, liquid, or solid.
PCBs (Polychlorinated biphenyls)
Toxic human-made compounds developed in 1929 and manufactured until 1977. They were used in a variety of products, such as transformers and fluorescent light ballasts. They are chemically inert and not biodegradable, and therefore banned in 1979. However, since products already in use didn’t have to be replaced, they are still being introduced into our environment. Found in surface and groundwater, they are drawn to sediment, where they can remain indefinitely. They continue to be found in the flesh of fish and other animals and have been found to cause birth defects and other health problems in humans.
Pentanes plus
A mixture of hydrocarbons, mostly pentanes and heavier fractions, extracted from natural gas.
Perfluorocarbons (PFCs)
A group of human-made chemicals composed of carbon and fluorine only. These chemicals (predominantly CF4 and C2F6) were introduced as alternatives, along with hydrofluorocarbons, to the ozone depleting substances. In addition, PFCs are emitted as by-products of industrial processes and are also used in manufacturing. PFCs do not harm the stratospheric ozone layer, but they are powerful greenhouse gases CF4 has a global warming potential (GWP) of 6,500 and C2F6 has a GWP of 9,200.
Permafrost
A layer of ground below the surface that is permanently frozen.
Petrochemicals
Chemicals obtained by refining (i.e., distilling) crude oil. They are used as raw materials in the manufacture of most industrial chemicals, fertilizers, pesticides, plastics, synthetic fibers, paints, medicines, and many other products.
Petroleum coke
A residue that is the final product of the condensation process in cracking.
Petroleum
A generic term applied to oil and oil products in all forms, such as crude oil, lease condensate, unfinished oils, petroleum products, natural gas plant liquids, and non-hydrocarbon compounds blended into finished petroleum products.
Photochemical smog
Ozone air pollution. Ozone is a secondary pollutant because it requires sunlight (”photo”) and a chemical reaction between primary pollutants, NOx and Volatile Organic Compounds (VOCs), such as unburned gasoline or evaporating paint thinner. Also referred to as smog ozone.
Photosynthesis
A process in green plants and some other organisms that changes carbon dioxide and water into carbohydrates using energy from the sun. The process usually releases oxygen into the atmosphere as a by-product.
Photovoltaic and solar thermal energy
Energy radiated by the sun as electromagnetic waves (electromagnetic radiation) that is converted into electricity by means of solar (i.e., photovoltaic) cells or useable heat by concentrating (i.e., focusing) collectors.
Point source
A single identifiable source that discharges pollutants into the environment. Examples are smokestack, sewer, ditch, or pipe.
“Polluter Pays” Principle (PPP)
The principle that countries should in some way compensate others for the effects of pollution that they (or their citizens) generate or have generated.
Pollution
A change in the physical, chemical, or biological characteristics of the air, water, or soil that can affect the health, survival, or activities of humans in an unwanted way. Some expand the term to include harmful effects on all forms of life.
Polyvinyl chloride
(PVC) A polymer of vinyl chloride. It is tasteless, odorless and insoluble in most organic solvents. A member of the family vinyl resin, used in soft flexible films for food packaging and in molded rigid products, such as pipes, fibers, upholstery, and bristles.
POPs (persistent organic pollutants)
POPs are chemicals that stay around for a long time. They persist in the environment, bioaccumulate in the food web, and present a risk to human health and the environment. Their widespread distribution creates a threat across the globe.
Positive Feedback
A process that results in an amplification of the response of a system to an external influence. For example, increased atmospheric water vapor in response to global warming would be a positive feedback on warming, because water vapor is a GHG. Potable refers to drinkable. Water that is potable is clean and free from harmful chemicals and disease-carrying microbes.
Primary oil recovery
Pumping out the crude oil that flows by gravity into the bottom of an oil well.

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[ Q ]

QELRC (Quantified Emission Limitation and Reduction Commitment)
Also known as QELRO (Quantified Emission Limitation and Reduction Objective) The quantified commitments for GHG emissions listed in Annex B of the Kyoto Protocol. QELRCs are specified in percentages relative to 1990 emissions.

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[ R ]

Radiative Forcing
A change in the balance between incoming solar radiation and outgoing infrared radiation. Without any radiative forcing, solar radiation coming to the Earth would continue to be approximately equal to the infrared radiation emitted from the Earth. The addition of greenhouse gases traps an increased fraction of the infrared radiation, radiating it back toward the surface and creating a warming influence (i.e., positive radiative forcing because incoming solar radiation will exceed outgoing infrared radiation).
Radiosondes
Sensors carried aboard weather balloons that have been in continuous use since 1979 for the monitoring of tropospheric temperatures.
Rail
Includes “heavy” and “light” transit rail. Heavy transit rail is characterized by exclusive rights-of-way, multi-car trains, high-speed rapid acceleration, sophisticated signaling, and high platform loading. Also known as subway, elevated railway, or metropolitan railway (metro). Light transit rail may be on exclusive or shared rights of way, high or low platform, multi-car trains or single cars, automated or manually operated. In generic usage, light rail includes streetcars, trolley cars, and tramways.
Rainforest
A forest that receives more than 2.5 meters (8 feet) of rain each year. These forests cover only about 7% of the Earth’s surface but hold more than half of all plant and animal species on Earth.
Rainwater harvesting
Collecting rainwater to use for growing crops and for other human use. This practice can significantly reduce reliance on irrigation.
Ratification
After signing the UNFCCC or the Kyoto Protocol, a country must ratify it, often with the approval of its parliament or other legislature. In the case of the Kyoto Protocol, a Party must deposit its instrument of ratification with the UN Secretary General in New York.
Recycling
Collecting and reprocessing a resource so it can be used again. An example is collecting aluminum cans, melting them down, and using the aluminum to make new cans or other aluminum products.
Reforestation
Replanting of forests on lands that have recently been harvested.
Renewable energy
Energy obtained from sources that are essentially inexhaustible, unlike, for example, the fossil fuels, of which there is a finite supply. Renewable sources of energy include wood, waste, geothermal, wind, photovoltaic, and solar thermal energy.
Residual fuel oil
The heavier oils that remain after the distillate fuel oils and lighter hydrocarbons are distilled away in refinery operations and that conform to ASTM Specifications D396 and D975. Included are No. 5, a residual fuel oil of medium viscosity; Navy Special, for use in steam-powered vessels in government service and in shore power plants; and No. 6, which includes Bunker C fuel oil and is used for commercial and industrial heating, electricity generation, and to power ships. Imports of residual fuel oil include imported crude oil burned as fuel.

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[ S ]

Saltwater intrusion
Occurs when salt water enters a fresh-water aquifer. Rising sea levels can cause saltwater intrusion along coasts or on small islands. Another problem from salt can occur in soil. Overuse of water on crops (e.g., from irrigation ditches), can lead to salt build-up because the minerals (including salt) dissolved in water are left behind when water evaporates. This process is referred to as “salinization” and can harm soil, making it difficult or impossible to grow crops.
Second Assessment Report (SAR)
The Second Assessment Report, prepared by the Intergovernmental Panel on Climate Change, reviewed the existing scientific literature on climate change. Finalized in 1995, it is comprised of three volumes Science; Impacts, Adaptations and Mitigation; and Economic and Social Dimensions of Climate Change.
Secondary oil recovery
Injection of water into an oil well after primary oil recovery to force out some of the remaining thicker crude oil.
Secretariat of the UN Framework Convention on Climate Change
The United Nations staff assigned the responsibility of conducting the affairs of the UNFCCC. In 1996 the Secretariat moved from Geneva, Switzerland, to Bonn, Germany.
Sector
Division, most commonly used to denote type of energy consumer (e.g., residential) or according to the Intergovernmental Panel on Climate Change, the type of greenhouse gas emitter (e.g. industrial process).
Sequestration
Opportunities to remove atmospheric CO2, either through biological processes (e.g. plants and trees), or geological processes through storage of CO2 in underground reservoirs.
Shale oil
Slow-flowing, dark brown, heavy oil obtained when kerogen in oil shale is vaporized at high temperatures and then condensed. Shale oil can be refined to yield gasoline, heating oil, and other petroleum products.
Short Ton
Common measurement for a ton in the United States. A short ton is equal to 2,000 lbs or 0.907 metric tons.
Sink
A reservoir that uptakes a chemical element or compound from another part of its cycle. For example, soil and trees tend to act as natural sinks for carbon.
Smog ozone
Usually occurs on very hot days with little or no wind in areas with air pollution. It is another term for photochemical smog.
Smog
A word created in England in 1905 by combining “smoke” and “fog.” Originally it meant just that-smoke from burning coal and other fuels mixed with fog to create a haze. Now it is used for any kind of air pollution found in cities.
Soil carbon
A major component of the terrestrial biosphere pool in the carbon cycle. The amount of carbon in the soil is a function of the historical vegetative cover and productivity, which in turn is dependent in part upon climatic variables.
Solar energy
Direct radiant energy from the sun. It also includes indirect forms of energy such as wind, falling or flowing water (hydropower), ocean thermal gradients, and biomass, which are produced when direct solar energy interact with the earth.
Solar Radiation
Energy from the Sun. Also referred to as short-wave radiation. Of importance to the climate system, solar radiation includes ultraviolet radiation, visible radiation, and infrared radiation.
Source
Any process or activity that results in the net release of greenhouse gases, aerosols, or precursors of greenhouse gases into the atmosphere.
SRES Scenarios
A suite of emissions scenarios developed by the Intergovernmental Panel on Climate Change in its Special Report on Emissions Scenarios (SRES). These scenarios were developed to explore a range of potential future greenhouse gas emissions pathways over the 21st century and their subsequent implications for global climate change.
Stratospheric ozone
Ozone occurring naturally in the stratosphere. This ozone protects us from harmful ultraviolet rays.
Strip mining
Cutting deep trenches to remove minerals such as coal and phosphate found near the earth’s surface in flat or rolling terrain.
Subsidiary Body for Implementation (SBI)
A permanent body established by the UNFCCC that makes recommendations to the COP on policy and implementation issues. It is open to participation by all Parties and is composed of government representatives.
Subsidiary Body for Scientific and Technological Advice (SBSTA)
A permanent body established by the UNFCCC that serves as a link between expert information sources such as the IPCC and the COP.
Sulfate aerosols
Particulate matter that consists of compounds of sulfur formed by the interaction of sulfur dioxide and sulfur trioxide with other compounds in the atmosphere. Sulfate aerosols are injected into the atmosphere from the combustion of fossil fuels and the eruption of volcanoes like Mt. Pinatubo. Recent theory suggests that sulfate aerosols may lower the earth’s temperature by reflecting away solar radiation (negative radiative forcing). General Circulation Models which incorporate the effects of sulfate aerosols more accurately predict global temperature variations.
Sulfur
A pale yellow, nonmetallic element (chemical symbol S) that is found alone in nature but is also found in coal, oil, and natural gas. When these are burned, sulfur combines with oxygen to make sulfur dioxide (chemical symbol SO2), a toxic gas. In the atmosphere, sulfur dioxide can combine with hydrogen in water to make acid rain. Sulfur dioxide is also used to manufacture pesticides. It has a strong, sour, rotten-egg smell. About 99% of the sulfur dioxide in our atmosphere comes from fossil fuels and from other human related activities.
Sulfur cycle
Cyclic movement of sulfur in different chemical forms from the environment, to organisms, and then back to the environment.
Sulfur dioxide (SO2)
A compound composed of one sulfur and two oxygen molecules. Sulfur dioxide emitted into the atmosphere through natural and anthropogenic processes is changed in a complex series of chemical reactions in the atmosphere to sulfate aerosols. These aerosols are believed to result in negative radiative forcing (i.e., tending to cool the Earth’s surface) and do result in acid deposition (e.g., acid rain).
Sulfur Hexafluoride (SF6)
SF6 is among the six types of greenhouse gases to be curbed under the Kyoto Protocol. SF6 is a synthetic industrial gas largely used in heavy industry to insulate high-voltage equipment and to assist in the manufacturing of cable-cooling systems. There are no natural sources of SF6. SF6 has an atmospheric lifetime of 3,200 years. Its 100-year GWP is currently estimated to be 22,200 times that of CO2.
Surface mining
Removal of soil, sub-soil, and other strata and then extracting a mineral deposit found fairly close to the earth’s surface.
Sustainability
The measure by which a human activity can be continued without relying upon limited resources, such as fossil fuels, or by leaving waste behind, and also giving nature the chance to replenish itself.
Sustainable agriculture
Farming practices that make efficient use of renewable (or replaceable) resources and are based upon the fundamental principle of not harming the environment or local ecology. Choosing crops to suit the climate, thus reducing the need for irrigation, is one example.
Sustainable development
Human activities that do not do permanent damage to the environment or rob resources from future generations.
Synthetic natural gas
(SNG)” A manufactured product chemically similar in most respects to natural gas, resulting from the conversion or reforming of petroleum hydrocarbons. It may easily be substituted for, or interchanged with, pipeline quality natural gas.

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[ T ]

Trace Gas
Any one of the less common gases found in the Earth’s atmosphere. Nitrogen, oxygen, and argon make up more than 99 percent of the Earth’s atmosphere. Other gases, such as carbon dioxide, water vapor, methane, oxides of nitrogen, ozone, and ammonia, are considered trace gases. Although relatively unimportant in terms of their absolute volume, they have significant effects on the Earth’s weather and climate.
Troposphere
The lowest layer of the atmosphere and contains about 95 percent of the mass of air in the Earth’s atmosphere. The troposphere extends from the Earth’s surface up to about 10 to 15 kilometers. All weather processes take place in the troposphere. Ozone that is formed in the troposphere plays a significant role in both the greenhouse gas effect and urban smog.

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[ U ]

Unfinished oils
All oils requiring further refinery processing, except those requiring only mechanical blending. Includes naphtha and lighter oils, kerosene and light gas oils, heavy gas oils, and residuum.
United Nations Framework Convention on Climate
Change (UNFCC) The international treaty unveiled at the United Nations Conference on Environment and Development (UNCED) in June 1992. The UNFCCC 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. The UNFCCC also requires that all signatory parties develop and update national inventories of anthropogenic emissions of all greenhouse gases not otherwise controlled by the Montreal Protocol. Out of 155 countries that have ratified this accord, the United States was the first industrialized nation to do so.
Unsustainable
Refers to agricultural and other practices that depend upon nonrenewable (or non-replaceable) resources-such as fossil fuel, topsoil, or groundwater that eventually will be depleted.

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[ V ]

Volatile organic compounds (VOCs)
Organic compounds that evaporate readily into the atmosphere at normal temperatures. VOCs contribute significantly to photochemical smog production and certain health problems.

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[ W ]

Water Vapor
The most abundant greenhouse gas; it is the water present in the atmosphere in gaseous form. Water vapor is an important part of the natural greenhouse effect. While humans are not significantly increasing its concentration, it contributes to the enhanced greenhouse effect because the warming influence of greenhouse gases leads to a positive water vapor feedback. In addition to its role as a natural greenhouse gas, water vapor plays an important role in regulating the temperature of the planet because clouds form when excess water vapor in the atmosphere condenses to form ice and water droplets and precipitation.
Wood energy
Wood and wood products used as fuel, including roundwood (i.e., cordwood), limbwood, wood chips, bark, sawdust, forest residues, and charcoal.
World Health Organization (WHO)
A part of the United Nations founded in 1948, WHO helps people all over the world learn about and fight disease.

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[ X ]

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[ Y ]

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[ Z ]