Carbon dioxide (CO2) is a molecule composed of one atom of carbon and two atoms of oxygen. It is a colourless, non-toxic, inert, odourless and tasteless substance that is found as a gas in atmospheric conditions. Many natural processes generate CO2, such as respiration or fermentation. Carbon dioxide is largely produced by combustion, and it is this which is the cause of concern in the talk about global warming.
A key property of carbon dioxide is its ability to absorb a broad range of infrared light and re-emit it evenly in every direction. It is the absorption and re-emitting that ultimately prevents infrared light from leaving the atmosphere, hence resulting in a warming effect. The chemical characteristics of the molecule in combination with its high abundance in the atmosphere lead it to be considered a major greenhouse gas.
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