Top: Increasing atmospheric CO₂ levels as measured in the atmosphere and ice cores. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single An ice core is a Core sample from the accumulation of snow and ice over many years that have re-crystallized and have trapped air bubbles from previous time periods Bottom: The amount of net carbon increase in the atmosphere, compared to carbon emissions from burning fossil fuel. Fossil fuels or mineral fuels are fossil source Fuels that is Hydrocarbons found within the top layer of the Earth’s crust.

Greenhouse gases are the gases present in the atmosphere which reduce the loss of heat into space and therefore contribute to global temperatures through the greenhouse effect. An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " The Greenhouse effect refers to the change in the Thermal equilibrium temperature of a planet or moon by the presence of an Atmosphere containing gas that absorbs Greenhouse gases are essential to maintaining the temperature of the Earth; without them the planet would be so cold as to be uninhabitable. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 ^[1][2] However, an excess of greenhouse gases can raise the temperature of a planet to lethal levels, as on Venus where the 96. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is Structure and composition Composition The atmosphere of Venus is composed mainly of Carbon dioxide, along with a small amount of Nitrogen and other 5% carbon dioxide (CO₂) atmosphere results in surface temperatures of about 467 °C (872 °F). Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Greenhouse gases are produced by many natural and industrial processes, which currently result in CO₂ levels of 380 ppmv in the atmosphere. "Parts-per" notation is used especially in Science and Engineering, to denote Ratios (relative proportions in measured quantities particularly Based on ice-core samples and records (see graphs) current levels of CO₂ are approximately 100 ppmv higher than during immediately pre-industrial times, when direct human influence was negligible.

The greenhouse effect

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. The Greenhouse effect refers to the change in the Thermal equilibrium temperature of a planet or moon by the presence of an Atmosphere containing gas that absorbs An absorption band is a range of Wavelengths (or equivalently frequencies) in the Electromagnetic spectrum which are able to excite a particular 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. In Physics, a black body is an object that absorbs all light that falls on it Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of 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. Sensible heat is Potential energy in the form of thermal energy or Heat. 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 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 Greenhouse effect refers to the change in the Thermal equilibrium temperature of a planet or moon by the presence of an Atmosphere containing gas that absorbs The term is a misnomer though, as this process is not the mechanism that warms greenhouses. The Greenhouse effect refers to the change in the Thermal equilibrium temperature of a planet or moon by the presence of an Atmosphere containing gas that absorbs

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

• water vapor
• carbon dioxide
• methane
• nitrous oxide
• ozone
• CFCs

The most important greenhouse gases are:

• water vapor, which causes about 36–70% of the greenhouse effect on Earth. General properties of water vapor Evaporation/sublimation Whenever a water molecule leaves a surface it is said to have evaporated Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Nitrous oxide, commonly known as " laughing gas," is a Chemical compound with the Chemical formula N 2 O. OZONE is an object oriented Operating system written in the C programming language. The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane General properties of water vapor Evaporation/sublimation Whenever a water molecule leaves a surface it is said to have evaporated (Note clouds typically affect climate differently from other forms of atmospheric water. Cloud forcing (sometimes described as cloud radiative forcing) is the difference between the radiation budget components for average Cloud conditions and cloud-free )
• 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. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. OZONE is an object oriented Operating system written in the C programming language. 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 Greenhouse effect refers to the change in the Thermal equilibrium temperature of a planet or moon by the presence of an Atmosphere containing gas that absorbs (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). Nitrous oxide, commonly known as " laughing gas," is a Chemical compound with the Chemical formula N 2 O. Sulfur hexafluoride is an Inorganic compound with the formula. The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane Perfluorocarbons (PFCs are compounds derived from Hydrocarbons by replacement of Hydrogen Atoms by Fluorine atoms The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane This is a list of anthropogenic Greenhouse gases as used by the IPCC TAR

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. Diatomic molecules are molecules made only of two Atoms of either the same or different Chemical elements The prefix di- means two in Greek Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of 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.

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. The Holocene is a Geological epoch which began approximately 10000 years ago (about 8000 BC Since the industrial revolution, concentrations of all the long-lived greenhouse gases have increased due to human actions. The Industrial Revolution was a period in the late 18th and early 19th centuries when major changes in agriculture manufacturing and transportation had a profound effect on the ^[5]

Ice cores provide evidence for variation in greenhouse gas concentrations over the past 800,000 years. An ice core is a Core sample from the accumulation of snow and ice over many years that have re-crystallized and have trapped air bubbles from previous time periods Both CO₂ and CH₄ vary between glacial and interglacial phases, and concentrations of these gases correlate strongly with temperature. Before the ice core record, direct measurements do not exist. Various proxies and modelling suggests large variations; 500 Myr ago CO₂ levels were likely 10 times higher than now. ^[6] Indeed higher CO₂ concentrations are thought to have prevailed throughout most of the Phanerozoic eon, with concentrations four to six times current concentrations during the Mesozoic era, and ten to fifteen times current concentrations during the early Palaeozoic era until the middle of the Devonian period, about 400 Mya. The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the Geologic timescale, and the one during which abundant animal life has existed The Devonian is a geologic period and system of the Paleozoic era spanning from to  million years ago. ^[7][8][9] The spread of land plants is thought to have reduced CO₂ concentrations during the late Devonian, and plant activities as both sources and sinks of CO₂ have since been important in providing stabilising feedbacks. ^[10] Earlier still, a 200-million year period of intermittent, widespread glaciation extending close to the equator (Snowball Earth) appears to have been ended suddenly, about 550 Mya, by a colossal volcanic outgassing which raised the CO₂ concentration of the atmosphere abruptly to 12%, about 350 times modern levels, causing extreme greenhouse conditions and carbonate deposition as limestone at the rate of about 1mm per day. The Snowball Earth Hypothesis as it was originally proposed]] Evidence The Snowball Earth hypothesis was originally devised to explain the apparent presence of Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 ^[11] This episode marked the close of the Precambrian eon, and was succeeded by the generally warmer conditions of the Phanerozoic, during which multicellular animal and plant life evolved. No volcanic carbon dioxide emission of comparable scale has occurred since. In the modern era, emissions to the atmosphere from volcanoes are only about 1% of emissions from human sources. ^[11][12]

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). Global warming is the increase in the average measured temperature of the 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. Climate Change 2007, the Fourth Assessment Report (AR4 of the United Nations Intergovernmental Panel on Climate Change ( IPCC) is the fourth

Per capita anthropogenic greenhouse gas emissions by country for the year 2000 including land-use change.

Since about 1750 human activity has increased the concentration of carbon dioxide and of some other important greenhouse gases. Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus ^[13] Natural sources of carbon dioxide are more than 20 times greater than sources due to human activity,^[14] but over periods longer than a few years natural sources are closely balanced by natural sinks such as weathering of continental rocks and photosynthesis of carbon compounds by plants and marine plankton. As a result of this balance, the atmospheric concentration of carbon dioxide remained between 260 and 280 parts per million for the 10,000 years between the end of the last glacial maximum and the start of the industrial era. ^[15]

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. Fossil fuels or mineral fuels are fossil source Fuels that is Hydrocarbons found within the top layer of the Earth’s crust. Deforestation is the conversion of Forested areas to non-forest land for use such as Arable land, Pasture, urban use logged area or wasteland Land use change (mainly deforestation in the tropics) account for up to one third of total anthropogenic CO₂ emissions. ^[15]
• livestock enteric fermentation and manure management,^[16] paddy rice farming, land use and wetland changes, pipeline losses, and covered vented landfill emissions leading to higher methane atmospheric concentrations. Enteric fermentation is fermentation that takes place in the Digestive systems of Ruminant Animals It is one of the factors in increased Rice is a Cereal foodstuff which forms an important part of the diet of many people worldwide and as such it is a staple food for many 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. Refrigeration is the process of removing Heat from an enclosed space or from a substance and moving it to a place where it is unobjectionable A fire extinguisher is an Active fire protection device used to extinguish or control small fires often in emergency situations
• agricultural activities, including the use of fertilizers, that lead to higher nitrous oxide concentrations. Nitrous oxide, commonly known as " laughing gas," is a Chemical compound with the Chemical formula N 2 O.

The seven sources of CO₂ from fossil fuel combustion are (with percentage contributions for 2000–2004):^[17]

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. Natural gas is a Gaseous Fossil fuel consisting primarily of Methane but including significant quantities of Ethane, Propane, In the most general sense of the word a cement is a binder a substance which sets and hardens independently and can bind other materials together Fuel oil is a fraction obtained from Petroleum Distillation, either as a distillate or a residue S. EPA ranks the major greenhouse gas contributing end-user sectors in the following order: industrial, transportation, residential, commercial and agricultural^[18]. 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. Building insulation refers broadly to any object in a building used as Insulation for any purpose Miles per gallon ( MPG) is a metric term that measures how many miles a vehicle can travel 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. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Nitrous oxide, commonly known as " laughing gas," is a Chemical compound with the Chemical formula N 2 O. Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 Sulfur hexafluoride is an Inorganic compound with the formula. The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane 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 in an effort ^[19]

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. The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane For other similarly-named agreements see Montreal Convention (disambiguation. 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 Earth's Note that ozone depletion has only a minor role in greenhouse warming though the two processes often are confused in the media.

Role of water vapor

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%. General properties of water vapor Evaporation/sublimation Whenever a water molecule leaves a surface it is said to have evaporated ^[20] Water vapor concentrations fluctuate regionally, but human activity does not directly affect water vapor concentrations except at local scales (for example, near irrigated fields).

The Clausius-Clapeyron relation establishes that warmer air can hold more water vapor per unit volume. The Clausius-Clapeyron relation, named after Rudolf Clausius and Émile Clapeyron, is a way of characterizing the Phase transition between two phases of 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. This article is about the theories and mathematics of climate modeling Relative humidity is a measurement of the amount of Water vapor that exists in a gaseous mixture of air and water Thus water vapor acts as a positive feedback to the forcing provided by greenhouse gases such as CO₂. ^[21]

Greenhouse gas emissions

Main article: List of countries by carbon dioxide 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). This is a list of sovereign states by carbon dioxide emissions due to human activity Carbon dioxide forms approximately 004% of the Earth's atmosphere. From the same ice cores it appears that CO₂ concentrations stayed between 260 and 280 ppm during the preceding 10,000 years. 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,^[22] though others have argued that these findings more likely reflect calibration/contamination problems rather than actual CO₂ variability. ^[23][24]

Since the beginning of the Industrial Revolution, the concentrations of many of the greenhouse gases have increased. The Industrial Revolution was a period in the late 18th and early 19th centuries when major changes in agriculture manufacturing and transportation had a profound effect on the 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. ^[25]. Many observations are available online in a variety of Atmospheric Chemistry Observational Databases. 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 The greenhouse gases with the largest radiative forcing are:

Global anthropogenic Carbon emissions 1751–2004. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Year 1751 ( MDCCLI) was a Common year starting on Friday (link will display the full calendar of the Gregorian calendar (or a "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again "

(Source: IPCC radiative forcing report 1994 updated (to 1998) by IPCC TAR table 6. Year 1994 ( MCMXCIV) was a Common year starting on Saturday (link will display full 1994 Gregorian calendar) 1 [6][7]).

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. Carbon intensity can refer to The ratio of Carbon Dioxide to energy a measure of the "greenness" of different fuels 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. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 ^[17] In comparison, methane has not increased appreciably, and N₂O by 0. 25% y⁻¹. ^[26]

Asia

Atmospheric levels of the main greenhouse gas have set another new peak in a sign of the industrial rise of Asian economies led by China. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National ^[27] Over the 2000-2010 interval China is expected to increase its carbon emissions by 600 MT, largely because of the rapid construction of old-fashioned power plants in poorer internal provinces. ^[28]

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. See also Climate change in the United States Until recently the United States was the largest emitter of carbon dioxide emissions United States federal register of greenhouse gas emissions Even though the United States has not adopted the requirements of the Kyoto Protocol, it has still made significant 3% more GHG in 2005 than it did in 1990. ^[29] 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. The U. S. is followed by the United States with about 5,800 megatonnes.

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. ^[30] Although these tonnages are small compared to the CO₂ in the Earth's atmosphere, they are significantly larger than pre-industrial levels. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five

Long-term trend

Year-to-year increase of atmospheric CO₂

Atmospheric carbon dioxide concentration is increasing at an increasing rate. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single In the 1960s, the average annual increase was only 37% of what it was in 2000 through 2007. ^[31]

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). Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state Hydroxyl in Chemistry stands for a molecule consisting of an Oxygen atom and a Hydrogen atom connected by a Covalent bond. In Chemistry, radicals (often referred to as free radicals) are atoms molecules or ions with Unpaired electrons on an otherwise Open shell Global warming potential (GWP is a measure of how much a given mass of Greenhouse gas is estimated to contribute to Global warming. 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. In Physics and Fluid mechanics, a boundary layer is that layer of Fluid in the immediate vicinity of a bounding surface
• 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). Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. Carbonic acid (ancient name acid of air or aerial acid) has the formula H2CO3 In Inorganic chemistry, bicarbonate ( IUPAC -recommended nomenclature hydrogencarbonate) is an intermediate form in the Deprotonation In Chemistry, a carbonate is a salt or Ester of Carbonic acid.
• as a consequence of a photochemical change. Photochemistry, a sub-discipline of Chemistry, is the study of the interactions between Atoms, small Molecules, and light (or Electromagnetic radiation 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). Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays In Chemistry, radicals (often referred to as free radicals) are atoms molecules or ions with Unpaired electrons on an otherwise Open shell The stratosphere is the second major layer of Earth's atmosphere, just above the Troposphere, and below the Mesosphere. OZONE is an object oriented Operating system written in the C programming language.
• as a consequence of dissociative ionization caused by high energy cosmic rays or lightning discharges, which break molecular bonds. For the 1962 Bruce Conner film see Cosmic Ray (film Cosmic rays are energetic particles originating from space that impinge on For example, lightning forms N anions from N₂ which then react with O₂ to form NO₂. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge

Per capita responsibility for current anthropogenic atmospheric CO₂

Atmospheric lifetime

Jacob (1999)^[32] 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. Chemical species are Atoms Molecules molecular fragments Ions etc Box models are simplified versions of complex systems reducing them to boxes (or Reservoirs linked by fluxes 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 (F_out), chemical loss of X (L), and deposition of X (D) (all in kg/sec): ^[32]

The atmospheric lifetime of a species therefore measures the time required to restore equilibrium following an increase in its concentration in the atmosphere. In Chemistry, deposition is the settling of particles ( Atoms or Molecules or Sediment from a Solution, suspension and mixture 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. 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 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.

Examples of the atmospheric lifetime and GWP for several greenhouse gases include:

• CO₂ has a variable atmospheric lifetime, and cannot be specified precisely. Global warming potential (GWP is a measure of how much a given mass of Greenhouse gas is estimated to contribute to Global warming. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single ^[33] 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. ^[34][35] 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. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. 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. Nitrous oxide, commonly known as " laughing gas," is a Chemical compound with the Chemical formula N 2 O.
• CFC-12 has an atmospheric lifetime of 100 years and a GWP of 10600 over 100 years. Dichlorodifluoromethane ( R-12) usually sold under the Brand name Freon-12, is a Chlorofluorocarbon Halomethane, commonly known
• HCFC-22 has an atmospheric lifetime of 12. Chlorodifluoromethane or difluoromonochloromethane is a Hydrochlorofluorocarbon (HCFC 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. Tetrafluoromethane, also known as carbon tetrafluoride, Freon-14 and R 14, is a Carbon Fluoride (CF4
• Sulfur hexafluoride has an atmospheric lifetime of 3,200 years and a GWP of 22000 over 100 years. Sulfur hexafluoride is an Inorganic compound with the formula.

Source: IPCC, table 6.7.

The use of CFC-12 (except some essential uses) has been phased out due to its ozone depleting properties^[36]. Dichlorodifluoromethane ( R-12) usually sold under the Brand name Freon-12, is a Chlorofluorocarbon Halomethane, commonly known 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 Earth's The phasing-out of less active HCFC-compounds will be completed in 2030^[37]. The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane

Airborne fraction

Airborne fraction (AF) is the proportion of a emission (e. The airborne fraction is a scaling factor defined as the ratio of the annual increase in atmospheric {{chem|CO|2}} to the emissions from anthropogenic sources. g. CO₂) remaining in the atmosphere after a specified time. Canadell (2007)^[38] 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. ^[38]

Global warming potential

The global warming potential (GWP) depends on both the efficiency of the molecule as a greenhouse gas and its atmospheric lifetime. Global warming potential (GWP is a measure of how much a given mass of Greenhouse gas is estimated to contribute to Global warming. 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.

Related effects

MOPITT 2000 global carbon monoxide

Carbon monoxide has an indirect radiative effect by elevating concentrations of methane and tropospheric ozone through scavenging of atmospheric constituents (e. MOPITT ( Measurements of Pollution in the Troposphere) is a payload scientific instrument launched into Earth Orbit by NASA on 2000 ( MM) was a Leap year that started on Saturday of the Common Era, in accordance with the Gregorian calendar. Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Ozone (O3 is a key constituent of the Troposphere (it is also an important constituent of certain regions of the Stratosphere g. , the hydroxyl radical, OH) that would otherwise destroy them. Hydroxyl in Chemistry describes a molecule consisting of an Oxygen atom and a Hydrogen atom joined by a Covalent bond. 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 dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Carbon monoxide has an atmospheric lifetime of only a few months^[39] and as a consequence is spatially more variable than longer-lived gases.

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)^[40] argue that the contribution to climate change from methane is at least double previous estimates as a result of this effect. ^[41]

See also

References

External links

Greenhouse gas at the Open Directory Project

• The NOAA Annual Greenhouse Gas Index (AGGI). The Open Directory Project ( ODP) also known as dmoz (from directory
• Greenhouse Gases Sources, Levels, Study results — University of Michigan; eia. doe. gov findings
• How Much Greenhouse Gas Does the United States Emit?
• Greenhouse-gas reduction technologies for coal-fired power generation.
• Kenya legislation aims to cut industrial gas emissions, March 2008 [8]

Carbon dioxide emissions

• International Energy Annual: Reserves
• International Energy Annual 2003: Carbon Dioxide Emissions
• International Energy Annual 2003: Notes and Sources for Table H.1co2 (Metric tons of carbon dioxide can be converted to metric tons of carbon equivalent by multiplying by 12/44)
• DOE — EIA — Alternatives to Traditional Transportation Fuels 1994 — Volume 2, Greenhouse Gas Emissions (includes "Greenhouse Gas Spectral Overlaps and Their Significance")
• NOAA Paleoclimatology Program — Vostok Ice Core
• NOAA CMDL CCGG — Interactive Atmospheric Data Visualization NOAA CO₂ data
• Carbon Dioxide Information Analysis Centre FAQ Includes links to Carbon Dioxide statistics
• Little Green Data Book 2007, World Bank. Lists C02 statistics by country, including per capita and by country income class.
• Flight Carbon Emission Calculator
• Database of carbon emissions of power plants

Methane emissions

• BBC News — Thawing Siberian bogs are releasing more methane
• METHANE-EATING BUG HOLDS PROMISE FOR CUTTING GREENHOUSE GAS. Media Release, GNS Science, New Zealand

Policy and advocacy

• Australian Greenhouse Gas Initiative
• Global Green Plan, a not-for profit organisation based in Melbourne, Australia, developing school curriculum to teach youth how to reduce emissions
• Carbon Dioxide is Good for the Environment 2001 paper by the National Center for Public Policy Research
• Environmental Effects of Increased Atmospheric Carbon Dioxide paper by the Oregon Institute of Science and Medicine
• EU page about reducing CO₂ emissions from light-duty vehicles : the EU's aim is to reach — by 2010 at the latest — an average CO₂ emission figure of 120 g/km for all new passenger cars marketed in the Union. The National Center for Public Policy Research, founded in 1982, is a self-described conservative Think tank in the United States. The Oregon Institute of Science and Medicine (OISM is a 501(c(3 Non-profit organization located about seven miles from Cave Junction Oregon.