Beginning of Essay
, aside from pollution is one of scientists biggest concerns. is caused by the Greenhouse effect. There are 4 steps in the Greenhouse effect. 1-Sunlight radiates from the sun, through space, to EarthÆs atmosphere. 2- The sunlight enters the atmosphere and hits E ....

Middle of Essay
.... carbon dioxide, methane, nitrous oxide, and ozone depleting substances such as CFCs, also known as Chlorofluorocarbons, hydrofluorocarbons, and perfluorocarbons. These gases are generated a number of human activities such as fossil fuel combustion, waste disposal in landfills, the use of a refrigerator, numerous agricultural and industrial activities, and the cutting down of numerous forests. These human practices have already changed the chemical make up of the atmosphere. Between the pre-industrial times and today, we have seen the concentration of carbon dioxide rise 30% in some regions, in particular the northern hemisphere, human practices have ....