Greenhouse gases are those that absorb infrared radiation in the atmosphere, creating a “greenhouse effect” that contributes to Global Warming. In agriculture, these gases are mainly carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4), chlorofluorocarbons (CFC) and others.
Carbon dioxide (CO2) is a naturally occurring gas that is also a by-product of burning fossil fuels or biomass land-use changes and other industrial processes. CO2 is the reference gas against which other greenhouse gases are measured.
Nitrous oxide (N2O) is a powerful greenhouse gas with a global warming potential of 296 times that of carbon dioxide. Major sources of nitrous oxide include soil cultivation practices, especially the use of commercial and organic fertilizers; fossil fuel combustion; nitric acid production and biomass burning.
Methane (CH4) is a hydrocarbon and a greenhouse gas with a global warming potential most recently estimated at 23 times that of carbon dioxide. Methane is produced through anaerobic (without oxygen) decomposition of waste in landfills, animal digestion, decomposition of animal excretions, production and distribution of natural gas and petroleum, coal production, and incomplete fossil fuel combustion.
Chlorofluorocarbons (CFC), hydrochlorofluorocarbons (HCFC) and hydrofluorocarbons (HFC) are mainly used for refrigeration, air conditioning, packaging, insulation, solvents and aerosol propellants. CFC gases are currently being replaced by other compounds, less toxic in terms of Global Warming Potential, including HCFC and, most importantly, HFC.
Source (extracts): US Environmental Protection Agency