The Greenhouse Effect

Most scientists believe recent global warming is the result of human influence on a naturally-occurring phenomenon called the greenhouse effect. Under normal conditions some of the sun's heat is radiated back into space.

The 'greenhouse effect' occurs when heat is trapped in the atmosphere by gases like carbon dioxide, methane and CFCs The Sun's energy heats the surface of the Earth, although some of that heat is radiated back into space and the planet cools. Some gases in the atmosphere, called the greenhouse gases, prevent this radiation and so trap the heat.

Since the Industrial Revolution, humans have been pumping out huge quantities of greenhouse gases, most notably carbon dioxide. Before 1850 human activity had little influence on the amount of carbon dioxide in the atmosphere, but since the industrial revolution concentrations of carbon dioxide, methane, nitrous oxide and chlorofluorocarbons, or CFCs, have greatly increased. Burning fossil fuels is responsible for most of the increase in carbon dioxide. The upsurge in concentrations of methane is due to gas produced by livestock and rice paddies.