are being loaded into it, an inevitable consequence of the burning of coal, oil, and natural gas. In the atmosphere, carbon dioxide acts like a blanket, trapping heat and radiating some of it back down to Earth. This process of heat trapping is enhancing the greenhouse effect.
The level of atmosphere carbon dioxide has increased by more than 30% since the beginning of the Industrial Revolution (Lieberman 19). Most of that rise is due to fuel burning, but it also has resulted from the massive deforestation that has occurred during the past 200 years and continues today as, worldwide, an area of tropical forest nearly the size of Pennsylvania is cut and cleared each year. Carbon, which constitutes about half the weight of wood, converts to carbon dioxide when felled trees either rot or are burned. Carbon dioxide is the main contributor to the warming, but other heat-trapping gases (ôgreenhouse gasesö) include nitrous oxide, methane, and chlorofluorocarbons. Nitrous oxide comes from excessive use of nitrogen fertilizers in agriculture. Methane emanates from rice paddies and cattle feedlots. Chlorofluorocarbons, emitted from styrofoam manufacturing and other industrial processes, not only trap heat, but destroy the EarthÆs protective stratospheric ozone layer as well. Except for the internationally regulated chlorofluorocarbons, these gases are being emitted to the atmosphere at ever-increasing rates as the human population increases and the scale of energy use, industrial activity, and agriculture grows.
Because of this human activity, the EarthÆs climate is changing. The surface temperature this century is as warm or warmer than any other century since at least 1400 AD; the temperature has increased by about 1 degree Fahrenheit over the last century; the last few decades have been the warmest this century; sea level has risen 4 to 10 inches; and mountain glaciers have retreated world-wide this century (McGraw-Hill 2)...