The key to global warming is the accumulated carbon dioxide and other air pollution that is increasing in the atmosphere like a thickening blanket that traps sun’s heat and causes warming on earth. Gases that trap heat in the atmosphere are known as greenhouse gases. The main human activities that contribute to global warming are the burning of fossil fuels (coal, oil, and natural gas) and the clearing of land.
Most of the burning occurs in automobiles, in factories, and in electric power plants that provide energy for houses...
