Acid Rain

             The temperature on earth's surface is determined by the solar radiation energy and heat reflected from the earth to outer space. Sunlight warms the surface, and then emits energy in the form infrared rays, or heat. Then a certain percentage of these rays are absorbed in the by atmospheric gases, thus heating the atmosphere which in turn radiates heat back toward earth's surface. With this process, known as the "greenhouse effect", the earth's average surface temperature is kept around 15 C. If not for this process the temperature of the earth would drop by over 30C to about -18C, making it nearly unsuitable for us to survive. .
             Since the Industrial Revolution, there has been a significant increase in the emission of greenhouse gases, the majority of which is carbon dioxide. Chlorofluorocarbon and sulfur hexafluoride, other greenhouse gases, were introduced into the atmosphere for the first time following the Industrial Revolution. With this increase of greenhouse gases, the balance of heat exchange between solar radiation energy and the heat reflected from the earth towards space is shattered. Now greater amounts of heat are kept in the atmosphere causing the temperature near earth's surface to rise in a phenomenon known as global warming. .
             The greenhouse gas carbon dioxide has increased dramatically since the end of the 18th century, as a by product of the combustion of fossil fuels such as coal, petroleum and natural gas. Prior to the Industrial Revolution, the carbon dioxide atmospheric concentration was about 280 ppmv, and as of 1994 it has reached 358 ppmv. As of 1992, carbon dioxide made a 63.7 percent contribution of the global warming due to greenhouse gases from to human activity. If carbon dioxide continues to be produced at the same rate, figures are expected to reach 500 ppmv in 2050 and 700 ppmv by the year 2100.
             Methane, which accounts for 19.