E3+Global+Warming

__Global warming and greenhouse effect__
__E3.1 Global Warming__ Our planet is very cleverly designed, it has it's own invisible shield, protecting us all from harmful cosmic and solar radiation. Without this shield (known as the ozone layer), our planet would burn. The increase in carbon emissions, however, is not escaping our atnosphere, past the ozone layer, and is causing our planet to heat up. This is known as Global Warming . Greenhouse gases (GHGs) refer to gases that absorb the infrared radiation from the sun and warm the lower atmosphere, such as carbon dioxide, nitrous oxide, methane, sulphur hexafluoride (SF 6 ) and hydroflourocarbons. __E3.2 The main greenhouse gases and their sources and effects__


 * ~ Gases ||~ Sources of gases ||~ Contribution to global warming ||
 * Carbon dioxide CO2 || Produced naturally by the decomposition of organic materials, growing plants, and weathering of rocks. || 50% ||
 * Methane CH4 || Formed by the bacterial decomposition of vegetation under water that occurs in flooded rice fields || 18% ||
 * Chlorofluorocarbons CFC's || Refrigerants, popellants, foaming agents and solvents || 14% ||
 * Oxides O3 || Secondary pollutants in photochemical smogs || 12% ||
 * Nitrogen oxides N2O || This is formed during combustion of hydrocarbons and over use of a3rtificial fertilizers || 6% ||
 * Water vapour H2O || Always presented in the atmosphere (water cycle) || - ||
 * Their effects depend on their abundance and their ability to absorb heat radiation.

__E3.3 The influence of greenhouse gases on global warming__ Scientist accept that the current global warming is a direct consequence of the increased emission of greenhouse gases. Effects include climate change, thermal expansion of the oceans and melting of the polar ice caps and gaciers.

__E3.4 The influence of particulates on the Earth's surface temperature__ Particulates such as volcanic dust (by scattering the short wave radiation from the sun and reflecting it back into space) which therefore lowers the temperature.