Greenhouse Effect


Carbon Dioxide (CO2) is the most prominent Greenhouse gas. It is pumped into the atmosphere at a rate of about 30 billion tons per year. This is largely from the burning of fossil fuels and deforestation. Although other greenhouse gases are more potent in absorbing radiation, none are pumped into the atmosphere in quantities that carbon dioxide is.

Our reliance on the automobile contributes significant amounts of carbon dioxide to the atmosphere.


Methane is a colorless, odorless, flammable gas. It is produced when bacteria decompose dead plant and animal matter in the absence of oxygen. Large deposits of methane can be found deep underground where oil and coal reserves are located. Methane is abundant around lakes and swamps. Through activities such as rice cultivation, raising of livestock, mining, drilling for gas and oil we add up to 500 million tons each year. Methane stays in the atmosphere for only 10 years, but is capable of trapping 20 times more heat than the same number of carbon dioxide molecules.


Nitrous oxide(N2O) is another colorless greenhouse gas. This gas is part of the nitrogen cycle and is released naturally by bacteria in the oceans and soil. Through the use of nitrogen containing fertilisers, car pollution and sewage treatment plants we add up to 13 million tons into the atmosphere every year.


CFC (chlorofluorocarbon) is a term used to describe any organic, synthetic molecule that contains fluorine and chlorine. These synthetic molecules are able to be converted easily form liquid to gas and back to the liquid state. As a result of this property they were heavily used in aerosols and as the coolant in many refrigerators and air-conditioners. Because of the devastating damage the CFCs have on the ozone layer they have been replaced with less damaging hydrocarbons. Hydrocarbons are not dangerous to the ozone layer but they do absorb infrared radiation and as such contribute to global warming.


Water vapour is considered a greenhouse gas. Like carbon dioxide, it to can absorb and retain heat in the atmosphere. However its contribution to global warming remains controversial. As the earth warms up, more water will evaporate from the oceans and of course increase the concentration of water vapour in the atmosphere that can absorb heat. However, this is a little over simplified because the effect of cloud formations have not being considered.


Although clouds are formed from water vapour, which is a greenhouse gas, they nevertheless participate in reflecting infrared radiation (heat) back into space. This has a cooling effect and makes the role of water vapour in global warming less certain.



Carbon dioxide does not absorb radiation as well as other Greenhouse gases. Why is carbon dioxide considered more harmful, to the atmosphere, than other Greenhouse gases?

Methane is also a Greenhouse gas. What human activities promote the increase in atmospheric methane?

Water vapour is a Greenhouse gas. However its effects on global warming are unclear. Explain why.