Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Greenhouse Gas shopping experience:

1. Compare - without doubt the biggest advantage that the Greenhouse Gas offers shoppers today is the ability to compare thousands of Greenhouse Gas at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.

2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about

3. Testimonials - don't know anybody that has bought a Greenhouse Gas? Wrong! If the Greenhouse Gas is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.

4. Questions - Got a question about Greenhouse Gas then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....

5. Reputation - Never heard of the company selling Greenhouse Gas? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Greenhouse Gas and build up a picture of their reputation for sales, returns, customer service, delivery etc.

6. Returns - still worried that even after all of the above your Greenhouse Gas wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.

7. Feedback - happy with your Greenhouse Gas then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.

8. Security - check for the yellow padlock on the Greenhouse Gas site before you buy, and the s after http:/ /i.e. https:// = a secure site

9. Contact - got a question about Greenhouse Gas, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.

10. Payment - ready to pay for your Greenhouse Gas, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.

s. Bottom: The amount of net carbon increase in the atmosphere, compared to carbon emissions from burning fossil fuel.

Greenhouse gases are components of the Earth's atmosphere that contribute to the greenhouse effect. Without the greenhouse effect the Earth would be uninhabitable;http://www.sciencemag.org/cgi/content/full/302/5651/1719 in its absence, the mean temperature of the earth would be about -19 °C (-2 °F, 254 K) rather than the present mean temperature of about 15 °C (59 °F, 288 K)http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch01.pdf. Greenhouse gases include in the order of relative abundance water vapor, carbon dioxide, methane, nitrous oxide, and ozone. The majority of greenhouse gases come mostly from natural sources but are also contributed to by human activity.

The "greenhouse effect" s 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 Black body at Wien's displacement law than does the sun. 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 also is warmed by transfer of sensible heat 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, as this process is not the Greenhouse effect#Real greenhouses.

The major greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect on Earth (Cloud forcing); carbon dioxide, which causes 9-26%; methane, which causes 4-9%, and ozone, which causes 3-7%. 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.) Other greenhouse gases include, but are not limited to, nitrous oxide, sulfur hexafluoride, hydrofluorocarbons, perfluorocarbons and chlorofluorocarbons (see IPCC list of greenhouse gases).

The major atmospheric constituents (N2 and O2) are not greenhouse gases. This is because diatomic 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.

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.

Anthropogenic greenhouse gases 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 Fourth Assessment Report.The concentrations of several greenhouse gases have increased over time. Human activity increases the greenhouse effect primarily through release of carbon dioxide, but human influences on other greenhouse gases can also be important.Some of the main sources of greenhouse gases due to human activity include:

The seven sources of CO2 from fossil fuel combustion are (with percentage contributions for 2000-2004):
  • Solid fuels (e.g. coal): 35%
  • Liquid fuels (e.g. gasoline): 36%
  • Gaseous fuels (e.g. natural gas): 20%
  • Flaring gas industrially and at wells:

    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. . Many observations are available on line in a variety of Atmospheric Chemistry Observational Databases. The greenhouse gases with the largest radiative forcing are:

    {]!Gas!Current (1998) Amount by volume!Increase over pre-industrial (1750)!Percentage increase!Radiative forcing (Watt/metre²)|-| Carbon dioxide ] {383 ppm(2007.01)} || 87 ppm {105 ppm(2007.01)} || 31% {37.77%(2007.01)} || 1.46 {~1.532 (2007.01)}|-| Methane ] || 1,045 ppb || 150% || 0.48|-| Nitrous oxide ]–2000.

    {] and ozone depletion; all of the following have no natural sources and hence zero amounts pre-industrial!Gas!Current (1998)
    Amount by volume!Radiative forcing
    (W/m²)] || 268 Parts per trillion ||0.07|-| Dichlorodifluoromethane || 533 ppt ||0.17|-| Chlorofluorocarbon-113 || 84 ppt ||0.03|-| Carbon tetrachloride ] || 69 ppt || 0.03|}

    (Source: IPCC radiative forcing report 1994 updated (to 1998) by IPCC TAR table 6.1 ).

    Recent rates of change and emission The sharp acceleration in CO2 emissions since 2000 of >3% y-1 (>2 ppm y-1) from 1.1% y-1 during the 90's 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. All this indicates a global failure to decarbonise energy supply and an underestimation of emissions growth on the part of the IPCC in their Special Report on Emissions Scenarios. 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.Raupach, M.R. et al. (2007) "Global and regional drivers of accelerating CO2 emissions." Proc. Nat. Acad. Sci. 104(24): 10288-93. In comparison, methane has not increased appreciably, and N2O by 0.25% y-1.

    The United States emitted 16.3% more GHG in 2005 than it did in 1990.Emissions inventory from the EPA, cited in Science News, vol. 171, p. 318 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. It is followed by the United States with about 5,800 megatonnes. 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. Although these tonnages of are small compared to the carbon dioxide in the Earth's atmosphere, they are significantly larger than pre-industrial levels.

    Removal from the atmosphere and global warming potential

    Aside from water vapor near the surface, which has a residence time of days, most greenhouse gases take a very long time to leave the atmosphere. Although it is not easy to know with precision how long, there are estimates of the duration of stay, i.e., the time which is necessary so that the gas disappears from the atmosphere, for the principal greenhouse gases. For the first five years of this century, 48% of total anthropogenic CO2 emissions remained in the atmosphere, a figure that is increasing and diagnostic of weakening carbon sinks. Greenhouse gases can be removed from the atmosphere by various processes:



    Two scales can be used to describe the effect of different gases in the atmosphere. The first, the atmospheric lifetime, describes how long it takes to restore the system to equilibrium following a small increase in the concentration of the gas in the atmosphere. Individual molecules may interchange with other reservoirs such as soil, the oceans, and biological systems, but the mean lifetime refers to the decaying away of the excess. It is sometimes erroneously claimed that the atmospheric lifetime of CO2 is 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, uptake by photosynthesis, or other processes. 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.

    The second scale is global warming potential (GWP). The 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.

    Examples of the atmospheric lifetime and GWP for several greenhouse gases include: doi=10.1029/2004JC002625 | accessdate=2007-07-27--> Carbon dioxide is defined to have a GWP of 1 over all time periods.

    Source : IPCC, table 6.7.

    Related effects 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.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 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)Shindell, Drew T.; Faluvegi, Greg; Bell, Nadine; Schmidt, Gavin A. "An emissions-based view of climate forcing by methane and tropospheric ozone", Geophysical Research Letters, Vol. 32, No. 4 argue that the contribution to climate change from methane is at least double previous estimates as a result of this effect. Methane's Impacts on Climate Change May Be Twice Previous Estimates

    See also

    References External links

    Carbon dioxide emissions

    Methane emissions

    Policy and advocacy

    s. Bottom: The amount of net carbon increase in the atmosphere, compared to carbon emissions from burning fossil fuel.

    Greenhouse gases are components of the Earth's atmosphere that contribute to the greenhouse effect. Without the greenhouse effect the Earth would be uninhabitable;http://www.sciencemag.org/cgi/content/full/302/5651/1719 in its absence, the mean temperature of the earth would be about -19 °C (-2 °F, 254 K) rather than the present mean temperature of about 15 °C (59 °F, 288 K)http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_Ch01.pdf. Greenhouse gases include in the order of relative abundance water vapor, carbon dioxide, methane, nitrous oxide, and ozone. The majority of greenhouse gases come mostly from natural sources but are also contributed to by human activity.

    The "greenhouse effect" s 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 Black body at Wien's displacement law than does the sun. 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 also is warmed by transfer of sensible heat 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, as this process is not the Greenhouse effect#Real greenhouses.

    The major greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect on Earth (Cloud forcing); carbon dioxide, which causes 9-26%; methane, which causes 4-9%, and ozone, which causes 3-7%. 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.) Other greenhouse gases include, but are not limited to, nitrous oxide, sulfur hexafluoride, hydrofluorocarbons, perfluorocarbons and chlorofluorocarbons (see IPCC list of greenhouse gases).

    The major atmospheric constituents (N2 and O2) are not greenhouse gases. This is because diatomic 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.

    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.

    Anthropogenic greenhouse gases 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 Fourth Assessment Report.The concentrations of several greenhouse gases have increased over time. Human activity increases the greenhouse effect primarily through release of carbon dioxide, but human influences on other greenhouse gases can also be important.Some of the main sources of greenhouse gases due to human activity include:

    The seven sources of CO2 from fossil fuel combustion are (with percentage contributions for 2000-2004):
  • Solid fuels (e.g. coal): 35%
  • Liquid fuels (e.g. gasoline): 36%
  • Gaseous fuels (e.g. natural gas): 20%
  • Flaring gas industrially and at wells:

    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. . Many observations are available on line in a variety of Atmospheric Chemistry Observational Databases. The greenhouse gases with the largest radiative forcing are:

    {]!Gas!Current (1998) Amount by volume!Increase over pre-industrial (1750)!Percentage increase!Radiative forcing (Watt/metre²)|-| Carbon dioxide ] {383 ppm(2007.01)} || 87 ppm {105 ppm(2007.01)} || 31% {37.77%(2007.01)} || 1.46 {~1.532 (2007.01)}|-| Methane ] || 1,045 ppb || 150% || 0.48|-| Nitrous oxide ]–2000.

    {] and ozone depletion; all of the following have no natural sources and hence zero amounts pre-industrial!Gas!Current (1998)
    Amount by volume!Radiative forcing
    (W/m²)] || 268 Parts per trillion ||0.07|-| Dichlorodifluoromethane || 533 ppt ||0.17|-| Chlorofluorocarbon-113 || 84 ppt ||0.03|-| Carbon tetrachloride ] || 69 ppt || 0.03|}

    (Source: IPCC radiative forcing report 1994 updated (to 1998) by IPCC TAR table 6.1 ).

    Recent rates of change and emission The sharp acceleration in CO2 emissions since 2000 of >3% y-1 (>2 ppm y-1) from 1.1% y-1 during the 90's 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. All this indicates a global failure to decarbonise energy supply and an underestimation of emissions growth on the part of the IPCC in their Special Report on Emissions Scenarios. 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.Raupach, M.R. et al. (2007) "Global and regional drivers of accelerating CO2 emissions." Proc. Nat. Acad. Sci. 104(24): 10288-93. In comparison, methane has not increased appreciably, and N2O by 0.25% y-1.

    The United States emitted 16.3% more GHG in 2005 than it did in 1990.Emissions inventory from the EPA, cited in Science News, vol. 171, p. 318 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. It is followed by the United States with about 5,800 megatonnes. 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. Although these tonnages of are small compared to the carbon dioxide in the Earth's atmosphere, they are significantly larger than pre-industrial levels.

    Removal from the atmosphere and global warming potential

    Aside from water vapor near the surface, which has a residence time of days, most greenhouse gases take a very long time to leave the atmosphere. Although it is not easy to know with precision how long, there are estimates of the duration of stay, i.e., the time which is necessary so that the gas disappears from the atmosphere, for the principal greenhouse gases. For the first five years of this century, 48% of total anthropogenic CO2 emissions remained in the atmosphere, a figure that is increasing and diagnostic of weakening carbon sinks. Greenhouse gases can be removed from the atmosphere by various processes:



    Two scales can be used to describe the effect of different gases in the atmosphere. The first, the atmospheric lifetime, describes how long it takes to restore the system to equilibrium following a small increase in the concentration of the gas in the atmosphere. Individual molecules may interchange with other reservoirs such as soil, the oceans, and biological systems, but the mean lifetime refers to the decaying away of the excess. It is sometimes erroneously claimed that the atmospheric lifetime of CO2 is 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, uptake by photosynthesis, or other processes. 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.

    The second scale is global warming potential (GWP). The 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.

    Examples of the atmospheric lifetime and GWP for several greenhouse gases include: doi=10.1029/2004JC002625 | accessdate=2007-07-27--> Carbon dioxide is defined to have a GWP of 1 over all time periods.

    Source : IPCC, table 6.7.

    Related effects 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.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 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)Shindell, Drew T.; Faluvegi, Greg; Bell, Nadine; Schmidt, Gavin A. "An emissions-based view of climate forcing by methane and tropospheric ozone", Geophysical Research Letters, Vol. 32, No. 4 argue that the contribution to climate change from methane is at least double previous estimates as a result of this effect. Methane's Impacts on Climate Change May Be Twice Previous Estimates

    See also

    References External links

    Carbon dioxide emissions

    Methane emissions

    Policy and advocacy



    UK Greenhouse Gas Inventory National System
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    National Statistics Online
    Total UK greenhouse gas emissions fell 8.1 per cent from 786.3 million to 722.3 million tonnes of carbon dioxide equivalent on an Environmental Accounts basis between 1990 and 2003

    Greenhouse gas conversion | Carbon Trust
    Green House Gases (GHG) have different properties which make some considerably more potent as greenhouse gases than others.

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    National Statistics Online
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    Reports
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    Greenhouse Gas



     
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