So what is Global Warming? According to the Oxford Dictionary Global Warming is the “increase in the temperature of the earth’s atmosphere caused by the greenhouse effect.” Although the concept of global warming had been lightly touched upon during the late 19th Century, only in recent decades has its significance been realized.

Some parts of the world will probably warm more than others. The warming of 2 to 5 degrees Celsius that scientists predict will occur by the middle of the next century is an increase in the average global temperature. Almost all climate models predict that warming will be greater at higher latitudes (nearer the poles) than at the equator. In fact, the warming t

Higher air temperatures also increase the concentration of ozone at ground level. The natural layer of ozone in the upper atmosphere blocks harmful ultraviolet radiation from reaching the earth’s surface, but in the lower atmosphere, ozone is a harmful pollutant. Global warming may also increase the risk of some infectious diseases, particularly those diseases that only appear in warm areas. Diseases that are spread by mosquitoes and other insects could become more prevalent if warmer temperatures enabled those insects to become established farther north; such "vector-borne" diseases include malaria, dengue fever, yellow fever, and encephalitis. Some scientists believe that algal blooms could occur more frequently as temperatures warm--particularly in areas with polluted waters--in which case diseases such a cholera that tend to accompany algal blooms could become more frequent.

Scientists are also certain that global warming will cause sea levels to rise. As temperatures increase worldwide, two things will occur to affect sea levels. First, as the surface water of the oceans gradually warm, the seawater will expand. This phenomenon is known as thermal expansion - as water is heated, it expands and takes up more space. It is predicted that thermal expansion alone will cause an increase of sea level of many inches. But as global temperatures continue to increase, it is assured that mountain glaciers, as well as the great masses of ice and snow that cover Greenland and the continent of Antarctica, will melt. As the ice covering these lands melts, huge quantities of water will flow into the oceans. This is expected to raise the level of the world’s oceans by many feet. These rising sea levels could flood coastal cities, wash away beaches, destroy expensive property, cover valuable crop land, and drive millions of people out of there homes. Many islands will eventually be in danger of disappearing altogether. A rise in sea level of more than two feet could cover large portions of many low-lying countries. In Bangladesh, for instance, at least one-fifth of the entire country could be underwater if sea levels rose just three feet. This would cause havoc, as millions of people would be forced to move in an already terribly overpopulated third world

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