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Greenhouse Gases and Their Global Warming Potential

Different greenhouse gases have varying abilities to trap heat. They have different global warming potential.

Gases that trap the heat in the atmosphere are called greenhouse gases. It is a proven fact that these greenhouse gases are a major cause of global warming. However, each of them contributes to global warming to a different extent. Global warming potential (GWP) is a term used to describe the relative contribution of various greenhouse gases. This ranks each greenhouse gas on mass basis in terms of its warming potential over a given period of time. Common greenhouse gases include carbon dioxide, methane, nitrous oxide and chlorofluorocarbons.

Carbon Dioxide

Carbon dioxide (CO2) is a greenhouse gas which contributes almost 60 percent of the “Enhanced greenhouse effect”- the greenhouse effect caused by anthropogenic activities. Burning of fossil fuels including coal, oil and natural gas is the main source of CO2. Cement manufacturing is another source of carbon dioxide. As trees consume CO2 during photosynthesis, they help maintain the level of CO2 in the atmosphere, thereby acting as CO2 sinks in the environment. Deforestation reduces the number of these sinks, thereby enhancing CO2 level in the atmosphere.  According to IPCC, the GWP of CO2 over next 100 years is 1; other gases are ranked relative to this index.

Methane

Although methane (CH4) is more potent in terms of global warming compared to CO2, it is present in atmosphere in very small quantities. It accounts for 15-20 percent of global warming. Its main sources include livestock, agriculture, anaerobic digestion in waste treatment plants, coal mining and leaks from natural gas reserves. According to IPCC, the GWP of CH4 over next 100 years is 20.

Nitrous Oxide

Nitrous Oxide (N2O) results from intensive agriculture and is also formed during combustion of fossil fuels and solid wastes. It contributes to 6 percent of the total greenhouse effect. Nonetheless, due to its high heat trapping efficiency, its GWP is 310.

Chlorofluorocarbons

Chlorofluorocarbons (CFCs) are the chemicals that do not exist naturally and come from anthropogenic origins. Their sources include production and usage of foams, aerosols, refrigerants and solvents. Although they are present in atmosphere in traces, their ability to trap heat is 15,000 times stronger than carbon dioxide. Thus their GWP ranges between 1500 and 8100 and they account for 25 percent of the total greenhouse effect.  

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