greenhouse effect

greenhouse effect Raised temperature at a planet's surface as a result of heat energy being trapped by gases in the atmosphere. As the Sun's rays pass through Earth's atmosphere, some heat is absorbed but most of the short-wave solar energy passes through. This energy is re-emitted by the Earth as long-wave radiation, which cannot pass easily through the atmosphere. More heat is retained if there is a cloud layer. In the last 100 years, more heat has been retained due to increased levels of carbon dioxide (CO₂) through the burning of fossil fuels. Tiny particles of CO₂ form an extra layer, which acts like the glass in a greenhouse. The effect is compounded by damage to the ozone layer caused by chlorofluorocarbons. Scientists of the Intergovernmental Panel on Climate Change (IPCC) estimate that a doubling of the present carbon dioxide emissions could lead to global warming on the scale of an average surface temperature rise of between 1 to 3.5°C. See also Earth Summit

http://www.epa.gov/globalwarming/kids/greenhouse.html