Since the beginning of Industrial Revolution, concentrations of carbon dioxide, methane, and nitrous oxide have all risen dramatically because of human activities. Fossil fuel combustion, land-use change, increasingly intensive agriculture, and an expanding global human population are the primary causes for these increases. Other greenhouse gases found in our planet's atmosphere include water vapor and ozone. Carbon dioxide is released into the atmosphere by the burning of solid waste, wood and wood products, and fossil fuels (oil, natural gas, and coal).
Nitrous oxide emissions occur during various agricultural and industrial processes, and when solid waste or fossil fuels are burned.
Methane is emitted when organic waste decomposes, whether in landfills or in connection with livestock farming. Methane emissions also occur during the production and transport of fossil fuels.
The Properties of Greenhouse Gases
Greenhouse gases vary in their ability to absorb and hold heat in the atmosphere, a phenomenon known as the "greenhouse effect." HFCs and PFCs are the most heat-absorbent, but there are also wide differences between naturally occurring gases.
'F-gases' are man-made gases that included chlorofluoracarbons (CFCs), hydrofluorocarbons (HFCs) and sulphur hexafluoride (SF6). They are used as refrigerants, propellants and in electronics manufacture, but are highly persistent in the Earth's atmosphere. They are typically thousands of times more potent as greenhouse gases than carbon dioxide. While reductions in the use of CFCs have been underway in Western Nations for over twenty years, these chemicals are still used in some developing countries. The Montreal Protocol, the international agreement that phases out ozone-depleting substances, requires the end of chlorodifluoromethane production by 2020 in developed countries and 2030 in developing countries. CFCs have been gradually