Greenhouse gases are those thought to contribute to the greenhouse effect, an overall warming of the Earth as atmospheric gases trap electromagnetic radiation from the sun that would otherwise have been reflected back out into space.
Noteworthy greenhouse gases are methane, nitrous oxide, carbon dioxide, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). These gases are thought to affect the climate directly and indirectly, even though they constitute only a small fraction of the blanket of gases that make up the atmosphere.
Currently, the composition of the atmosphere is mostly nitrogen and oxygen, with just 0.033 percent carbon dioxide and all other gases accounting for even less.
