The Greenhouse Effect was first described by French scientist Joseph Fournier in 1824. It is a natural phenomenon that causes the Earth’s climate to warm up. It is the same phenomenon that greenhouses take advantage in order to provide natural warmth for plants.

High energy (short-wave) radiation from the sun travels through the atmosphere until it hits the surface of the Earth. The absorbed heat is then re-radiated as lower energy (infra-red) rays which are trapped (absorbed) by some of the gases in our atmosphere (the so-called Greenhouse Gases). The Greenhouse Effect maintains an average temperature of 15°C on the Earth – in fact, without the Greenhouse Effect, the temperature of the Earth would be minus 18°C! However, our protective atmosphere is now changing and this is causing excess heat to build up.

The greenhouse gases produced through human activity are:
 CO2 - emitted mainly through fossil fuel combustion
 H4 (methane and natural gas) - emitted mainly by agriculture, mining and quarrying and household waste landfills.
 Nitrous oxides (N2O)
 Tropospheric ozone (O3).
 Chlorofluorocarbones (CFC HCFC) and their substitutes (HFC, PFC and SF6).

Greenhouse Gases occur naturally in relatively low concentrations. However, human activity has significantly changed the greenhouse gas concentrations in the atmosphere; the concentration of CO2, the main greenhouse gas, has increased by 30% since the pre-industrial era.