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Encyclopedia > Greenhouse gas
Top: Increasing atmospheric CO2 levels as measured in the atmosphere and ice cores. Bottom: The amount of net carbon increase in the atmosphere, compared to carbon emissions from burning fossil fuel.

Main article: Greenhouse effect
Pattern of absorption bands created by greenhouse gases in the atmosphere and their effect on both solar radiation and upgoing thermal radiation

When sunlight reaches the surface of the Earth, some of it is absorbed and warms the surface. Because the Earth's surface is much cooler than the sun, it radiates energy at much longer wavelengths than the sun does, peaking in the infrared at about 10 µm. The atmosphere absorbs these longer wavelengths more effectively than it does the shorter wavelengths from the sun. The absorption of this longwave radiant energy warms the atmosphere; the atmosphere is also warmed by transfer of sensible and latent heat from the surface. Greenhouse gases also emit longwave radiation both upward to space and downward to the surface. The downward part of this longwave radiation emitted by the atmosphere is the "greenhouse effect". The term is a misnomer though, as this process is not the mechanism that warms greenhouses. A schematic representation of the exchanges of energy between outer space, the Earths atmosphere, and the Earth surface. ... Image File history File links Size of this preview: 595 Ã— 600 pixelsFull resolution (850 Ã— 857 pixel, file size: 75 KB, MIME type: image/png) // Shows how the absorption and recycling of energy by the atmosphere is a defining characteristic of the greenhouse effect. ... Image File history File links Size of this preview: 595 Ã— 600 pixelsFull resolution (850 Ã— 857 pixel, file size: 75 KB, MIME type: image/png) // Shows how the absorption and recycling of energy by the atmosphere is a defining characteristic of the greenhouse effect. ... An absorption band is a range of wavelengths (or, equivalently, frequencies) in the electromagnetic spectrum within which electromagnetic energy is absorbed by a substance. ... Solar irradiance spectrum at top of atmosphere. ... As the temperature decreases, the peak of the black body radiation curve moves to lower intensities and longer wavelengths. ... Wiens displacement law is a law of physics that states that there is an inverse relationship between the wavelength of the peak of the emission of a black body and its temperature. ... For other uses, see Infrared (disambiguation). ... Sensible heat is heat energy that is transported by a body that has a temperature higher than its surroundings via conduction, convection, or both. ... In thermochemistry, latent heat is the amount of energy in the form of heat released or absorbed by a substance during a change of phase (i. ... A schematic representation of the exchanges of energy between outer space, the Earths atmosphere, and the Earth surface. ... A schematic representation of the exchanges of energy between outer space, the Earths atmosphere, and the Earth surface. ...

On earth, the most abundant greenhouse gases are, in order of relative abundance:

The most important greenhouse gases are: Water vapor or water vapour (see spelling differences), also aqueous vapor, is the gas phase of water. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Methane is a chemical compound with the molecular formula . ... For other uses, see Nitrous oxide (disambiguation). ... For other uses, see Ozone (disambiguation). ... For other uses, see CFC (disambiguation). ...

• water vapor, which causes about 36–70% of the greenhouse effect on Earth. (Note clouds typically affect climate differently from other forms of atmospheric water.)
• carbon dioxide, which causes 9–26%
• methane, which causes 4–9%
• ozone, which causes 3–7%
Note that this is a combination of the strength of the greenhouse effect of the gas and its abundance. For example, methane is a much stronger greenhouse gas than CO2, but present in much smaller concentrations.

It is not possible to state that a certain gas causes a certain percentage of the greenhouse effect, because the influences of the various gases are not additive. (The higher ends of the ranges quoted are for the gas alone; the lower ends, for the gas counting overlaps.)[3][4] Other greenhouse gases include, but are not limited to, nitrous oxide, sulfur hexafluoride, hydrofluorocarbons, perfluorocarbons and chlorofluorocarbons (see IPCC list of greenhouse gases). A significant greenhouse gas not yet addressed by the IPCC (or the Kyoto Protocol) is nitrogen trifluoride.[5] Water vapor or water vapour (see spelling differences), also aqueous vapor, is the gas phase of water. ... Cloud forcing (sometimes described as cloud radiative forcing) is the difference between the radiation budget components for average cloud conditions and cloud-free conditions. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Methane is a chemical compound with the molecular formula . ... For other uses, see Ozone (disambiguation). ... A schematic representation of the exchanges of energy between outer space, the Earths atmosphere, and the Earth surface. ... For other uses, see Nitrous oxide (disambiguation). ... Sulfur hexafluoride is an inorganic compound with the formula . ... CFC molecules CFCs (chlorofluorocarbons) are a family of artificial chemical compounds containing chlorine, fluorine and carbon. ... Fluorotelomer alcohol FTOH 8:2 Perfluorocarbons (PFCs) are compounds derived from hydrocarbons by replacement of hydrogen atoms by fluorine atoms. ... For other uses, see CFC (disambiguation). ... This is a list of greenhouse gases as used by the IPCC TAR. Gases relevant to radiative forcing only (per IPCC documentation) Gases relevant to radiative forcing and ozone depletion (per IPCC documentation) (Source: IPCC radiative forcing report 1994 updated (to 1998) by IPCC TAR table 6. ... The Kyoto Protocol is a protocol to the international Framework Convention on Climate Change with the objective of reducing greenhouse gases that cause climate change. ... Nitrogen trifluoride, NF3, is a colorless, toxic, nonflammable, corrosive gas shipped in cylinders at high pressure. ...

The major atmospheric constituents (nitrogen, N2 and oxygen, O2) are not greenhouse gases. This is because homonuclear diatomic molecules such as N2 and O2 neither absorb nor emit infrared radiation, as there is no net change in the dipole moment of these molecules when they vibrate. Molecular vibrations occur at energies that are of the same magnitude as the energy of the photons on infrared light. Heteronuclear diatomics such as CO or HCl absorb IR; however, these molecules are short-lived in the atmosphere owing to their reactivity and solubility. As a consequence they do not contribute significantly to the greenhouse effect. N2 is a term used in several contexts N2 is the chemical formula for nitrogen gas. ... O2 or O-2 may be: Oceanic Airlines (Guinea) IATA airline designator Oxygen O2 plc, a telecommunications company. ... A computer rendering of the Nitrogen Molecule, which is a diatomic molecule. ... For other uses, see Infrared (disambiguation). ... Dipole moment refers to the quality of a system to behave like a dipole. ...

Late 19th century scientists experimentally discovered that N2 and O2 did not absorb infrared radiation (called, at that time, "dark radiation") and that CO2 and many other gases did absorb such radiation. It was recognized in the early 20th century that the known major greenhouse gases in the atmosphere caused the earth's temperature to be higher than it would have been without the greenhouse gases.

## Natural and anthropogenic

400,000 years of CO2

Most greenhouse gases have both natural and anthropogenic sources. During the pre-industrial holocene, concentrations of these gases were roughly constant. Since the industrial revolution, concentrations of all the long-lived greenhouse gases have increased due to human actions.[6] Graph of Vostok CO2/T/dust from Petit 1999 paper. ... Graph of Vostok CO2/T/dust from Petit 1999 paper. ... The Holocene epoch is a geological period, which began approximately 11,550 calendar years BP (about 9600 BC) and continues to the present. ... A Watt steam engine, the steam engine that propelled the Industrial Revolution in Britain and the world. ...

Gas Preindustrial Level Current Level   Increase since 1750   Radiative forcing (W/m2)
Carbon dioxide 280 ppm 384ppm 104 ppm 1.46
Methane 700 ppb 1,745 ppb 1,045 ppb 0.48
Nitric oxide 270 ppb 314 ppb 44 ppb 0.15
CFC-12 0 533 ppt 533 ppt 0.17

## Anthropogenic greenhouse gases

Global anthropogenic greenhouse gas emissions broken down into 8 different sectors for the year 2000.
The projected temperature increase for a range of greenhouse gas stabilization scenarios (the coloured bands). The black line in middle of the shaded area indicates 'best estimates'; the red and the blue lines the likely limits. From the work of IPCC AR4, 2007.
Per capita anthropogenic greenhouse gas emissions by country for the year 2000 including land-use change.

Some of the main sources of greenhouse gases due to human activity include:

• burning of fossil fuels and deforestation leading to higher carbon dioxide concentrations. Land use change (mainly deforestation in the tropics) account for up to one third of total anthropogenic CO2 emissions.[16]
• livestock enteric fermentation and manure management,[17] paddy rice farming, land use and wetland changes, pipeline losses, and covered vented landfill emissions leading to higher methane atmospheric concentrations. Many of the newer style fully vented septic systems that enhance and target the fermentation process also are sources of atmospheric methane.
• use of chlorofluorocarbons (CFCs) in refrigeration systems, and use of CFCs and halons in fire suppression systems and manufacturing processes.
• agricultural activities, including the use of fertilizers, that lead to higher nitrous oxide concentrations.

The seven sources of CO2 from fossil fuel combustion are (with percentage contributions for 2000–2004):[18] Fossil fuels or mineral fuels are fossil source fuels, that is, hydrocarbons found within the top layer of the earthâ€™s crust. ... This article is about the process of deforestation in the environment. ... Enteric fermentation is fermentation that takes place in the digestive systems of animals. ... For other uses, see Rice (disambiguation). ... Refrigeration is the process of removing heat from an enclosed space, or from a substance, and rejecting it elsewhere for the primary purpose of lowering the temperature of the enclosed space or substance and then maintaining that lower temperature. ... Halon 1211 and Halon 1301 are special-purpose fire extiguishing agents that were banned by the Montreal Protocol. ... Fire extinguisher A fire extinguisher is a device used to put out a fire, often in an emergency situation. ... For other uses, see Nitrous oxide (disambiguation). ...

1. Solid fuels (e.g. coal): 35%
2. Liquid fuels (e.g. gasoline): 36%
3. Gaseous fuels (e.g. natural gas): 20%
4. Flaring gas industrially and at wells: <1%
5. Cement production: 3%
6. Non-fuel hydrocarbons: <1%
7. The "international bunkers" of shipping and air transport not included in national inventories: 4%

The U.S. EPA ranks the major greenhouse gas contributing end-user sectors in the following order: industrial, transportation, residential, commercial and agricultural[19]. Major sources of an individual's GHG include home heating and cooling, electricity consumption, and transportation. Corresponding conservation measures are improving home building insulation, compact fluorescent lamps and choosing energy-efficient vehicles. Coal Example chemical structure of coal Coal is a fossil fuel formed in ecosystems where plant remains were saved by water and mud from oxidization and biodegradation. ... Petrol redirects here. ... For other uses, see Natural gas (disambiguation). ... Flare can mean several things: A pyrotechnic flare is a device used for illumination and signaling. ... For other uses, see Cement (disambiguation). ... -1... Common insulation applications inside an apartment building in Mississauga, Ontario, Canada. ... Low-energy light-bulb redirects here. ... Miles per gallon (MPG, or mpg) is a measure of fuel efficiency - the number of miles the car can run on one gallon of fuel. ...

Carbon dioxide, methane, nitrous oxide and three groups of fluorinated gases (sulfur hexafluoride, HFCs, and PFCs) are the major greenhouse gases and the subject of the Kyoto Protocol, which came into force in 2005.[20] Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Methane is a chemical compound with the molecular formula . ... For other uses, see Nitrous oxide (disambiguation). ... General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance Yellowish brown gas Atomic mass 18. ... Sulfur hexafluoride is an inorganic compound with the formula . ... CFC molecules CFCs (chlorofluorocarbons) are a family of artificial chemical compounds containing chlorine, fluorine and carbon. ... Fluorotelomer alcohol FTOH 8:2 Perfluorocarbons (PFCs) are compounds derived from hydrocarbons by replacement of hydrogen atoms by fluorine atoms. ... The Kyoto Protocol is a protocol to the international Framework Convention on Climate Change with the objective of reducing greenhouse gases that cause climate change. ...

Although CFCs are greenhouse gases, they are regulated by the Montreal Protocol, which was motivated by CFCs' contribution to ozone depletion rather than by their contribution to global warming. Note that ozone depletion has only a minor role in greenhouse warming though the two processes often are confused in the media. For other uses, see CFC (disambiguation). ... The largest Antarctic ozone hole recorded as of September 2006 For other similarly-named agreements, see Montreal Convention (disambiguation). ... Global monthly average total ozone amount Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earths stratosphere since the late 1970s; and a much larger, but seasonal, decrease in stratospheric ozone over Earth...

## Role of water vapour

Increasing water vapor at Boulder, Colorado.

Water vapor is a naturally occurring greenhouse gas and accounts for the largest percentage of the greenhouse effect, between 36% and 66%.[21] Water vapor concentrations fluctuate regionally, but human activity does not directly affect water vapor concentrations except at local scales (for example, near irrigated fields). Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Water vapor or water vapour (see spelling differences), also aqueous vapor, is the gas phase of water. ...

The Clausius-Clapeyron relation establishes that warmer air can hold more water vapor per unit volume. Current state-of-the-art climate models predict that increasing water vapor concentrations in warmer air will amplify the greenhouse effect created by anthropogenic greenhouse gases while maintaining nearly constant relative humidity. Thus water vapor acts as a positive feedback to the forcing provided by greenhouse gases such as CO2.[22] The Clausius-Clapeyron relation, in thermodynamics, is a way of characterizing the phase transition between two states of matter, such as solid and liquid. ... Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. ... A hygrometer used to measure the humidity of air. ...

## Greenhouse gas emissions

Measurements from Antarctic ice cores show that just before industrial emissions started, atmospheric CO2 levels were about 280 parts per million by volume (ppm; the units µL/L are occasionally used and are identical to parts per million by volume). From the same ice cores it appears that CO2 concentrations stayed between 260 and 280 ppm during the preceding 10,000 years. However, because of the way air is trapped in ice and the time period represented in each ice sample analised, these figures are long term averages not annual levels. Studies using evidence from stomata of fossilized leaves suggest greater variability, with CO2 levels above 300 ppm during the period 7,000–10,000 years ago,[23] though others have argued that these findings more likely reflect calibration/contamination problems rather than actual CO2 variability.[24][25] This is a list of countries by carbon dioxide emissions. ... Carbon dioxide in the Earths atmosphere is present in a low concentration. ...

Since the beginning of the Industrial Revolution, the concentrations of many of the greenhouse gases have increased. The concentration of CO2 has increased by about 100 ppm (i.e., from 280 ppm to 380 ppm). The first 50 ppm increase took place in about 200 years, from the start of the Industrial Revolution to around 1973; the next 50 ppm increase took place in about 33 years, from 1973 to 2006.[26]. Many observations are available online in a variety of Atmospheric Chemistry Observational Databases. The greenhouse gases with the largest radiative forcing are: A Watt steam engine, the steam engine that propelled the Industrial Revolution in Britain and the world. ... Over the last two centuries many atmospheric chemical observations have been made from a variety of ground-based, airborne, and orbital platforms and deposited in databases. ...

Gas Current (1998) Amount by volume Increase over pre-industrial (1750) Percentage increase Radiative forcing (W/m²)
Carbon dioxide
365 ppm {383 ppm(2007.01)}
87 ppm {105 ppm(2007.01)}
31% {37.77%(2007.01)}
1.46 {~1.532 (2007.01)}
Methane
1,745 ppb
1,045 ppb
150%
0.48
Nitrous oxide
314 ppb
44 ppb
16%
0.15
Global anthropogenic Carbon emissions 17512004.
Relevant to both radiative forcing and ozone depletion; all of the following have no natural sources and hence zero amounts pre-industrial
Gas Current (1998)
Amount by volume
(W/m²)
CFC-11
268 ppt
0.07
CFC-12
533 ppt
0.17
CFC-113
84 ppt
0.03
Carbon tetrachloride
102 ppt
0.01
HCFC-22
69 ppt
0.03

### Recent rates of change and emission

Greenhouse gas intensity in 2000 including land-use change

The sharp acceleration in CO2 emissions since 2000 of >3% y−1 (>2 ppm y−1) from 1.1% y−1 during the 1990s is attributable to the lapse of formerly declining trends in carbon intensity of both developing and developed nations. Although over 3/4 of cumulative anthropogenic CO2 is still attributable to the developed world, China was responsible for most of global growth in emissions during this period. Localised plummeting emissions associated with the collapse of the Soviet Union have been followed by slow emissions growth in this region due to more efficient energy use, made necessary by the increasing proportion of it that is exported.[18] In comparison, methane has not increased appreciably, and N2O by 0.25% y−1.[27] Image File history File links GHG_intensity_2000. ... Image File history File links GHG_intensity_2000. ... Carbon intensity is the ratio of carbon emissions to economic activity or some other activity. ...

#### Asia

Atmospheric levels of CO2 have set another new peak, partly a sign of the industrial rise of asian economies led by China.[28] Over the 2000-2010 interval China is expected to increase its carbon dioxide emissions by 600 Mt, largely because of the rapid construction of old-fashioned power plants in poorer internal provinces.[29]

#### United States

Main articles: Greenhouse gas emissions by the United States and United States federal register of greenhouse gas emissions

The United States emitted 16.3% more GHG in 2005 than it did in 1990.[30] According to a preliminary estimate by the Netherlands Environmental Assessment Agency, the largest national producer of CO2 emissions since 2006 has been China with an estimated annual production of about 6200 megatonnes. China is followed by the United States with about 5,800 megatonnes. Although the per capita emission figures of China are still about one quarter of those of the US population. Atmospheric Carbon Dioxide versus Time The United States is historically the worlds largest greenhouse gas emitter. ...

Major greenhouse gas trends

Relative to 2005, China's fossil CO2 emissions increased in 2006 by 8.7%, while in the USA, comparable CO2 emissions decreased in 2006 by 1.4%. The agency notes that its estimates do not include some CO2 sources of uncertain magnitude.[31] These figures rely on national CO2 data that do not include aviation. Although these tonnages are small compared to the CO2 in the Earth's atmosphere, they are significantly larger than pre-industrial levels. Global trends in major greenhouse gases. ... Global trends in major greenhouse gases. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Air redirects here. ...

### Long-term trend

Year-to-year increase of atmospheric CO2

Atmospheric carbon dioxide concentration is increasing at an increasing rate. In the 1960s, the average annual increase was only 37% of what it was in 2000 through 2007.[32] Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ...

## Removal from the atmosphere and global warming potential

Aside from water vapor, which has a residence time of days, most greenhouse gases take many years to leave the atmosphere. Although it is not easy to know with precision how long it takes greenhouse gases to leave the atmosphere, there are estimates for the principal greenhouse gases.

Greenhouse gases can be removed from the atmosphere by various processes:

• as a consequence of a physical change (condensation and precipitation remove water vapor from the atmosphere).
• as a consequence of chemical reactions within the atmosphere. This is the case for methane. It is oxidized by reaction with naturally occurring hydroxyl radical, OH· and degraded to CO2 and water vapor at the end of a chain of reactions (the contribution of the CO2 from the oxidation of methane is not included in the methane Global warming potential). This also includes solution and solid phase chemistry occurring in atmospheric aerosols.
• as a consequence of a physical interchange at the interface between the atmosphere and the other compartments of the planet. An example is the mixing of atmospheric gases into the oceans at the boundary layer.
• as a consequence of a chemical change at the interface between the atmosphere and the other compartments of the planet. This is the case for CO2, which is reduced by photosynthesis of plants, and which, after dissolving in the oceans, reacts to form carbonic acid and bicarbonate and carbonate ions (see ocean acidification).
• as a consequence of a photochemical change. Halocarbons are dissociated by UV light releasing Cl· and F· as free radicals in the stratosphere with harmful effects on ozone (halocarbons are generally too stable to disappear by chemical reaction in the atmosphere).
• as a consequence of dissociative ionization caused by high energy cosmic rays or lightning discharges, which break molecular bonds. For example, lightning forms N anions from N2 which then react with O2 to form NO2.
Per capita responsibility for current anthropogenic atmospheric CO2

Jacob (1999)[33] defines the lifetime τ of an atmospheric species X in a one-box model as the average time that a molecule of X remains in the box. Mathematically τ can be defined as the ratio of the mass m (in kg) of X in the box to its removal rate, which is the sum of the flow of X out of the box (Fout), chemical loss of X (L), and deposition of X (D) (all in kg/sec): $tau = frac{m}{F_{out}+L+D}$ [33] Chemical species is a common, general name for atoms, molecules, molecular fragments and ions as entities being subjected to a chemical process or to a measurement. ... Deposition is a term used in chemistry to describe the settling of particles or sediment from a solution or suspension mixture, or the production of a solid on a pre-existing surface. ...

The atmospheric lifetime of a species therefore measures the time required to restore equilibrium following an increase in its concentration in the atmosphere. Individual atoms or molecules may be lost or deposited to sinks such as the soil, the oceans and other waters, or vegetation and other biological systems, reducing the excess to background concentrations. The average time taken to achieve this is the mean lifetime. The atmospheric lifetime of CO2 is often incorrectly stated to be only a few years because that is the average time for any CO2 molecule to stay in the atmosphere before being removed by mixing into the ocean, photosynthesis, or other processes. However, this ignores the balancing fluxes of CO2 into the atmosphere from the other reservoirs. It is the net concentration changes of the various greenhouse gases by all sources and sinks that determines atmospheric lifetime, not just the removal processes. Given an assembly of elements, the number of which decreases ultimately to zero, the lifetime (also called the mean lifetime) is a certain number that characterizes the rate of reduction (decay) of the assembly. ...

Examples of the atmospheric lifetime and GWP for several greenhouse gases include: Global warming potential (GWP) is a measure of how much a given mass of greenhouse gas is estimated to contribute to global warming. ...

• CO2 has a variable atmospheric lifetime, and cannot be specified precisely.[34] Recent work indicates that recovery from a large input of atmospheric CO2 from burning fossil fuels will result in an effective lifetime of tens of thousands of years.[35][36] Carbon dioxide is defined to have a GWP of 1 over all time periods.
• Methane has an atmospheric lifetime of 12 ± 3 years and a GWP of 62 over 20 years, 23 over 100 years and 7 over 500 years. The decrease in GWP associated with longer times is associated with the fact that the methane is degraded to water and CO2 by chemical reactions in the atmosphere.
• Nitrous oxide has an atmospheric lifetime of 120 years and a GWP of 296 over 100 years.
• CFC-12 has an atmospheric lifetime of 100 years and a GWP of 10600 over 100 years.
• HCFC-22 has an atmospheric lifetime of 12.1 years and a GWP of 1700 over 100 years.
• Tetrafluoromethane has an atmospheric lifetime of 50,000 years and a GWP of 5700 over 100 years.
• Sulfur hexafluoride has an atmospheric lifetime of 3,200 years and a GWP of 22000 over 100 years.

Source: IPCC, table 6.7. Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Methane is a chemical compound with the molecular formula . ... For other uses, see Nitrous oxide (disambiguation). ... For other uses, see CFC (disambiguation). ... Freon is a trade name for a group of chlorofluorocarbons used primarily as a refrigerant. ... Carbon tetrafluoride, CF4, is a carbon fluoride. ... Sulfur hexafluoride is an inorganic compound with the formula . ... IPCC is science authority for the UNFCCC The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess the risk of human-induced climate change. The Panel is open to all...

The use of CFC-12 (except some essential uses) has been phased out due to its ozone depleting properties[37]. The phasing-out of less active HCFC-compounds will be completed in 2030[38]. For other uses, see CFC (disambiguation). ... Global monthly average total ozone amount Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earths stratosphere since the late 1970s; and a much larger, but seasonal, decrease in stratospheric ozone over Earth... Tetrafluoroethane (a haloalkane) is a clear liquid which boils well below room temperature (as seen here) and can be extracted from common canned air canisters by simply inverting them during use. ...

### Airborne fraction

Airborne fraction (AF) is the proportion of a emission (e.g. CO2) remaining in the atmosphere after a specified time. Canadell (2007)[39] define the annual AF as the ratio of the atmospheric CO2 increase in a given year to that year’s total emissions, and calculate that of the average 9.1 PgC y-1 of total anthropogenic emissions from 2000 to 2006, the AF was 0.45. For CO2 the AF over the last 50 years (1956-2006) has been increasing at 0.25±0.21%/year.[39]

### Global warming potential

The global warming potential (GWP) depends on both the efficiency of the molecule as a greenhouse gas and its atmospheric lifetime. GWP is measured relative to the same mass of CO2 and evaluated for a specific timescale. Thus, if a molecule has a high GWP on a short time scale (say 20 years) but has only a short lifetime, it will have a large GWP on a 20 year scale but a small one on a 100 year scale. Conversely, if a molecule has a longer atmospheric lifetime than CO2 its GWP will increase with time. Global warming potential (GWP) is a measure of how much a given mass of greenhouse gas is estimated to contribute to global warming. ...

## Related effects

Carbon monoxide has an indirect radiative effect by elevating concentrations of methane and tropospheric ozone through scavenging of atmospheric constituents (e.g., the hydroxyl radical, OH) that would otherwise destroy them. Carbon monoxide is created when carbon-containing fuels are burned incompletely. Through natural processes in the atmosphere, it is eventually oxidized to carbon dioxide. Carbon monoxide has an atmospheric lifetime of only a few months[40] and as a consequence is spatially more variable than longer-lived gases. Download high resolution version (540x630, 61 KB)The MOPITT sensor aboard NASA’s Terra satellite has assembled the first view of carbon monoxide in the Earths atmosphere. ... Download high resolution version (540x630, 61 KB)The MOPITT sensor aboard NASA’s Terra satellite has assembled the first view of carbon monoxide in the Earths atmosphere. ... Categories: Stub ... Year 2000 (MM) was a leap year starting on Saturday. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ... Methane is a chemical compound with the molecular formula . ... Seasonal average concentrations of tropospheric ozone in Dobson units over the period 1979 to 2000. ... Hydroxide is a functional group consisting of oxygen and hydrogen: -O−H It has a charge of 1-. The term hydroxyl group is used when the functional group -OH is counted as a substituent of an organic compound. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ...

Another potentially important indirect effect comes from methane, which in addition to its direct radiative impact also contributes to ozone formation. Shindell et al (2005)[41] argue that the contribution to climate change from methane is at least double previous estimates as a result of this effect.[42]

Over the last two centuries many atmospheric chemical observations have been made from a variety of ground-based, airborne, and orbital platforms and deposited in databases. ... The atmospheric window refers to those parts of the electromagnetic spectrum that are, with the earths atmosphere in its natural state, not absorbed at all. ... Attribution of recent climate change is the effort to scientifically ascertain mechanisms responsible for relatively recent changes observed in the Earths climate. ... This is a list of countries by carbon dioxide emissions. ... A carbon dioxide (CO2) sink is a carbon dioxide reservoir that is increasing in size, and is the opposite of a carbon dioxide source. The main natural sinks are (1) the oceans and (2) plants and other organisms that use photosynthesis to remove carbon from the atmosphere by incorporating it... Category: ... A carbon audit regime is an effective means of accounting for greenhouse gas control efforts. ... Smog over Shanghai. ... The Climate Group is an independent, non-profit organization with 17 (as of August 2006) full-time staff and a network of associates based in the US, Europe and Australia. ... Air redirects here. ... Emission standards are requirements that set specific limits to the amount of pollutants that can be released into the environment. ... Environmental accounting can be considered either a subset or superset of accounting proper, because it aims to incorporate both economic and environmental information. ... There are numerous international environmental agreements made to protect the environment in different ways. ... The European Climate Change Programme (ECCP) was launched in June 2000 by the European Unions European Commission. ... Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... A schematic representation of the exchanges of energy between outer space, the Earths atmosphere, and the Earth surface. ... The main components of automobile exhaust are nitrogen (N2), carbon dioxide (CO2), and water vapor (H2O). ... The Effect of Burning Hydrocarbon Fuel The U.S. State Department is offering a nation-level perspective by releasing a draft of the Fourth US Climate Action Report (USCAR) to the United Nations Framework Convention on Climate Change. ... Global Atmosphere Watchs logo The Global Atmosphere Watch (GAW) is a worldwide system established by the World Meteorological Organization â€“ a United Nations agency â€“ to monitor trends in the Earths atmosphere. ... A hydrogen economy is a hypothetical economy in which the energy needed for motive power (for automobiles or other vehicle types) or electricity (for stationary applications) is derived from reacting hydrogen (H2) with oxygen. ... This is a list of countries ranked by greenhouse-gas emissions per capita in 2000. ... Holding Greenhouse gases are air pollutants, and the EPA may regulate their emission Court membership Chief Justice: John Roberts Associate Justices: John Paul Stevens, Antonin Scalia, Anthony Kennedy, David Souter, Clarence Thomas, Ruth Bader Ginsburg, Stephen Breyer, Samuel Alito Case opinions Majority by: Stevens Joined by: Kennedy, Souter, Ginsburg, Breyer... The North American Carbon Program (NACP) is one of the major elements of the Strategic Plan for the U.S. Climate Change Science Program. ... The Norwegian Polar Institute (in Norwegian: Norsk Polarinstitutt) is Norways national institution for polar research. ... Change in sea surface pH caused by anthropogenic CO2 between the 1700s and the 1990s Ocean acidification is the name given to the ongoing decrease in the pH of the Earths oceans, caused by their uptake of anthropogenic carbon dioxide from the atmosphere. ... The generalised concept of radiative forcing in climate science is any change in the radiation (heat) entering the climate system or changes in radiatively active gases. ... Eight states, shown in green, are participating in RGGI. Observers are not colorized. ... UN redirects here. ... IPCC is the science authority for the UNFCCC The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), to evaluate the risk of climate change brought on by humans, based mainly on... The Virgin Earth Challenge is a competition offering a \$25 million prize for the first person or organization to come up with a way of scrubbing greenhouse gases out of the atmosphere in the battle to beat global warming. ... Members of the Western Regional Climate Action Initiative (green). ... World power usage in terawatts (TW), 1965-2005. ...

## References

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 Greenhouse Gas Emissions | Climate Change | U.S. EPA (833 words) A greenhouse gas inventory is an accounting of the amount of greenhouse gases emitted to or removed from the atmosphere over a specific period of time (e.g., one year). Many states prepare greenhouse gas inventories, and EPA provides guidance and tools to assist them in their efforts. Corporate greenhouse gas inventories provide information on the emissions associated with the operations of a company.
 Greenhouse gas - Wikipedia, the free encyclopedia (2211 words) Greenhouse gases (GHGs) are gaseous components of the atmosphere that contribute to the "greenhouse effect". The downward part of this longwave radiation emitted by the atmosphere is the "greenhouse effect." The term is in fact a misnomer, as this process is not the primary mechanism that warms greenhouses. ) are not greenhouse gases, because homonuclear diatomic molecules (e.g.
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