1.1 The problem

Greenhouse gases (GHGs) are those that trap the infrared radiation emitted by the earth's surface thus warming the surface and the atmosphere. These gases include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFC), perfluorocarbons (PFC) and sulphur hexafluoride (SF6). Since 1750, the atmospheric concentrations have increased by 30%, 145% and 15% for the first three gases (Houghton et al. 1996: 3). This may lead to a mean global temperature rise of 1­3.5 degrees C by the end of this century, higher than that experienced over the last 10,000 years. Such a rise may lead to changes in the global atmospheric system, shifts in the climatic zones and shifts in extreme and mean weather conditions. This could also lead to a rise in the sea level of about 0.15 to 0.95 m and the melting of glaciers. This is referred to as the climate change phenomenon.