The Greenhouse Effect is caused by heat (short wave-length radiation) from the sun entering the Earth's atmosphere and being trapped by Greenhouse gases such as carbon dioxide and water vapour. This heat is absorbed by the Earth's surface, which is then re emitted back up into the atmosphere as long wave-length radiation. A proportion of this heat then escapes back out to space while the remainder is trapped causing the Greenhouse Effect. Under normal conditions a balance is maintained between the heat entering and leaving the Earth's atmosphere, producing a steady average global temperature.

However, due to the increased use of fossil fuels over the past hundred years, the concentration of carbon dioxide in the Earth's atmosphere has significantly increased. This has had the effect of trapping more heat and causing the average global temperature to rise, thus causing "Global Warming". Over the last 100 years the average global temperature has risen by 0.6 °C (South East Climate Change Partnership, 2002).

The 1997 Kyoto Protocol was designed to reduce the emission of Greenhouse gases throughout the world. Developed countries agreed to targets that will reduce their overall emissions of six gases. For the first time these targets will be legally binding, and differentiated between countries. Click here for more information on the Kyoto Protocol.

The UK Government has used the Kyoto Protocol to develop targets that go further than those agreed on an international level. It aims to reduce emissions of carbon dioxide by 20% below 1990 levels by 2010. These targets will be achieved partly by reviewing the way in which energy is generated, but also by improving energy efficiency in the home and work place.

For more information on the green house effect and global warming click here and go to the DEFRA web site.

The diagram below, produced by the MET Office, demonstrates the Greenhouse Effect.