Global warming is the heating of the earth. This heating occurs because of the greenhouse effect. The greenhouse effect is when carbon dioxide and other gases (methane and nitrous oxide) trap energy from the sun in our atmosphere. Most of the energy we receive from the sun is absorbed by the surface of the earth. Some of the energy is reflected and would normally exit our atmosphere; however, carbon dioxide absorbs this energy and it remains in our atmosphere. The more carbon dioxide in the atmosphere, the more heat we keep in. The United States Environmental Protection Agency reports that,
             "Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%...In 1997, the United States emitted about one-fifth of total global greenhouse gases." (EPA)
             Last century, the earth's temperature raised by 1oF. The nine hottest years of the last century were all in the last two decades. This value could have been even larger if it had not been for Mt. Pinatubo. This volcano erupted in 1991. The eruption put a large number of particles into the upper atmosphere, which reflected a great deal of energy from the sun. This eruption held down the earth's temperatures for about three years. There has been a measurable decrease in the snow cover of the northern hemisphere and Arctic sea ice. Precipitation in the lower 48 states has increased by 5%. These are all effects of global warming; however, scientists have not said whether or not these can be called good or bad. The greenhouse effect is always depicted as something bad. This is not the case. We depend on the greenhouse effect to withstand life on earth. The moon, which has no atmosphere (hence, no greenhouse effect) heats up to about 100oC during the day, when lit by the sun, and about –150o...