Greenhouse gases are those air emissions that contribute to global warming including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O)and other gases generated during industrial processes, including hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). These gases are measured in terms their global warming potential and are reported in tonnes of carbon dioxide equivalents (CO2-e) or million metric tonnes of carbon dioxide equivalents (MMTCDE). HFCs, PFCs and SF6 are the most heat-absorbent of the greenhouse gases listed above, with Global Warming Potentials of up to 11,700 for HFC-23 and 23,900 for SF6, implying that they trap 11,700 and 23,900 times more heat than carbon dioxide. The 100-year global warming potential for methane and nitrous oxide is 21 and 310 respectively.
