Greenhouse Gas (GHG)
A component of Earth’s atmosphere that traps heat in the atmosphere as part of the greenhouse effect. Although carbon dioxide is often used synonymously with the term GHG, other gases including water vapor, methane, nitrous oxide and ozone also contribute to the greenhouse effect. These gases are essential for absorbing the sunlight necessary to keep Earth warm enough to sustain life. However, when GHG levels increase sharply (as is true with global warming), too much heat is absorbed and Earth temperatures increase further.
Sources:
-- “Climate Change – Science,” EPA Web site. Accessed Sept. 5, 2007. http://www.epa.gov/climatechange/science/index.html
-- “Greenhouse Gas Emissions,” EPA Web site. Accessed Sept. 5, 2007. http://www.epa.gov/climatechange/emissions/index.html
-- “Greenhouse Gas,” Wikipedia. http://en.wikipedia.org/wiki/Greenhouse_gas
