Global Warming

Carbon dioxide is released to the atmosphere when solid waste, fossil fuels (oil, natural gas, and coal), and wood and wood products are burned. Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from the decomposition of organic wastes in municipal solid waste landfills, and the raising of livestock. Nitrous oxide is emitted during agricultural and industrial activities. Greenhouse gas absorbs heat in the atmosphere.
             Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30 percent, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15 percent (Mullin, 18). These increases have enhanced the heat-trapping capability of the earth's atmosphere. Scientists believe that the combustion of fossil fuels and other human activities are the primary reason for the increased level of carbon dioxide. Fossil fuels burned to run cars and trucks, heat homes and businesses, and power factories are responsible for about 98 percent of U.S. carbon dioxide emissions, 24 percent of methane emissions, and 18 percent of nitrous oxide emissions (Mullin, 22). Increased agriculture, deforestation landfills, industrial production, and mining also contribute a significant share of emissions. In 1997, the United States emitted about one-fifth of total global greenhouse gases (Mullin, 24).
             The 20th century's 10 warmest years all occurred in the last 15 years of the century. According to the Intergovernmental Panel on Climate Change global mean surface air temperatures have increased by between 0.5 and 1 degree Fahrenheit since the late 19th century (Patz, 11). Humans notice the change because there is an increase in the occurrence of extremely hot days and a decrease in the occurrence of extremely cold days. The snow cover in the Northern Hemisphere and floating ice in the Arctic Ocean have decreased.