Global Warming
...erely become more easily detectable in our time as temperatures have risen and scientists have devised more sophisticated ways to measure and forecast atmospheric processes. The atmospheric balance of “trace” gases actually started to change beyond natural bounds at the dawn of the industrial age, which induced the first large-scale burning of fossil fuels. It became noticeable in the 1880s, and an important force in global climate change by about 1980. After an intensifying debate, the idea that human activity is warming the earth in potentially damaging ways became generally accepted in scientific circles by 1995. (Ramanathan, and E.J. Welton. 2000.) Taken to extremes, an atmosphere plagued by the greenhouse effect can be very unpleasant. A demonstration would be the perpetually cloudy Venus, with an atmosphere in which carbon dioxide is the dominant element. The surface temperature on Venus, warmed considerably by runaway infrared forcing, is roughly 800 degrees F. The planet Mars, with nearly no infrared forcing in its atmosphere, averages minus 53 degrees C. Earth’s moderate degree of infrared forcing (along with its blanket of liquid water) keeps the planet habitable. When life first appeared on our planet, whether by chance or designs, it was possible only because the climate was friendly; it was neither too hot nor too cold. The atmosphere, containing water vapor, carbon dioxide, and other components, acted like the glass panels of a greenhouse, letting the sun's heat in but preventing some of it from escaping, thus warming the planet. If it were not for this greenhouse effect, temperatures at the earth's surface would be far colder than they are, and life as we know it could not exist. Global warming has become an issue of concern because of the perception that increasing greenhouse gases will cause the earth to warm so fast that nature may not be able to adapt to the rapid change. The atmosphere has always acted as a warming blanket around the earth. It is not the warmth of this blanket but the possibility of an abrupt or extreme temperature change that is causing some scientists concern. The popular view of global warming, the "myth,” has developed over the past decade because of computer climate models predictions. Environmental organizations have taken up the cause and demanded political action. At times the reaction to this view reaches a feverish pitch, generating hysteria. What is the global warming myth? It is a scenario of doom that contains certain facts and also certain assumptions: • Atmospheric carbon dioxide (CO 2) causes warming of the planet. • Man's activities are increasing the amount of carbon dioxide. • The average temperature of the earth has increased approximately 0.5°C (0.9°F) in the last 100 years. • Global temperature will increase another 1.5-4.5°C (2.7‐ 8.1°F) by sometime in the next century if we do not take drastic measures. • The predicted results of this warming include melting of the polar ice caps, flooding of coastal cities, massive extinction of species, and the Destruction of civilization as we know it. GREENHOUSE EFFECT The earth derives most of its energy from the sun, which continuously emits radiant energy equivalent to a 6,000°C, 11,000°F boiling caldron. This radiant energy, a very small portion of which reaches our stratosphere, consists of the full range of radiation including the ultraviolet (UV), visible, and infrared (IR) portions of the sun's spectrum. On the one hand, ultraviolet radiation, the most energetic portion, causes damage to living tissue if it is overexposed; it is UV radiation that causes sunburn and blinds people who stare directly at the sun. On the other hand, the interaction of UV and visible radiation within plants provides the energy required for the photosynthesis needed for plant growth. Since plants are the foundation of our food chain, this type of radiation is essential for all life. The visible portion of the sun's radiation is simply that to which our eyes are sensitive. We cannot see the UV or IR portions of the sun's spectrum, but we can feel the warmth of IR radiation. It is the same as of that which is radiated from an infrared heat lamp. The IR energy is too low to trigger our optical nerve endings, making our eyes not sensitive to this radiation. The sun furnishes the earth with a generous amount of ultraviolet, visible, and infrared radiation because it radiates at such a high temperature. The earth in turn radiates some of the sun's energy back into space at a very low temperature, about 15°C (59°F). Because of this low temperature, nearly all of the earth's radiation is in the low-energy infrared region. If there is a balance between the energy provided by the sun and that returned to space by the earth, the earth's temperature will remain constant. If the earth retains more energy than it returns to space it will heat up; inversely, if the earth retains less energy than is returned to space it will cool down. It is important to understand the nature of the atmosphere that blankets the earth. As altitude increases, pressure decreases. There is insufficient oxygen to support life at the top of the troposphere, which is about the altitude where commercial aircraft fly. It is estimated that 99% of the mass of the atmosphere is in the first 30 kilometers/20 miles of the ground. The mean diameter of the earth is 12,742 kilometers/8,000 miles, so the atmosphere is quite thin compared to the size of the earth. The focus of the global warming issue is on the troposphere and, to a limited degree, the stratosphere (Baranzini, & Chesney, 2003). GREENHOUSE GASES The components of the earth's atmosphere that trap radiation are called "greenhouse gases." The major components of our troposphere: oxygen, nitrogen, and argon are transparent to radiation, and thus they are not greenhouse gases. Only the minor and trace components are capable of interacting with solar radiation (Cox, 1991). The most important greenhouse gas is water vapor; others include carbon dioxide, hydrocarbons such as methane gas, various oxides of nitrogen and sulfur, and many man-made chemicals such as chlorofluorocarbons, or CFCs. People are CO 2 manufacturing machines. We breathe in oxygen from the air, convert it into carbon dioxide in our lungs, and breathe the carbon dioxide out. Plants do just the opposite, they breathe in carbon dioxide and breathe out oxygen. Each adult exhales about 1.5 liters of carbon dioxide per minute. The earth's population is over 5.2 billion, so there is a direct and significant input of carbon dioxide into the atmosphere just from humans breathing. Automobiles emit significant amounts of carbon dioxide, as well as trace amounts of carbon monoxide, oxides of nitrogen, and hydrocarbon gases. Electric power generation by means of coal, oil, or natural gas produces carbon dioxide and sulfur oxides. Many manufacturing processes create gaseous by-products as well. Water vapor is also generated by all of these sources; however, the water that evaporates from oceans and lakes far exceeds that produced by any human source. In fact, water vapor accounts for most of the greenhouse effect. According to the Intergovernmental Panel on Climate Change (IPCC) a large group of environmental scientists set up by the World Meteorological Organization and the United Nations Environment Program to study climate change, water vap...