Urbanization and Human Influence

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Urbanization and Human Influence It is estimated that by the year 2000, half the world population will live in urban environments (Porter and Brown, 1996). The US Bureau of the Census defines an area as being urbanized if a central city and its closely settled surrounding territory are of a certain size with 50,000 people and density of at least 1,000 people per square mile (Knox, 1994). A component of the definition denotes that human influence is a main aspect of urbanized areas in the process of urbanization. Unfortunately in order to create an urbanized area, a natural environment must be destroyed. Urbanization and human activity within an urban system produces many destructive and irreversible effects on natural environments such as climate change, air pollution, sediment and soil erosion, increased flooding magnitude, and loss of habitat. Cities in an urban environment change the local climate dramatically. Temperatures are always warmer in the city than it is in the surrounding areas creating a sort of "heat-island" (Harms, 1994). In a city, the sun’s energy is not used in the same way as in open landscapes with vegetation and trees. Concrete, stone, asphalt, and roofs tend to act as solar collectors and emit and absorb heat. The burning of fossil fuels also emit greenhouse gases like carbon dioxide that heat up the atmosphere around the source and usually the source is within urban environments. Cities also tend to be cloudier, rainier, and less humid than their surrounding areas. Cities are 10 percent rainier and 10 percent cloudier and have a 25 percent lower average wind speed, 30 percent more summer fog, and 100 percent more winter fog than nonurban areas (Keller, 1996). Average relative humidity is six percent... ... middle of paper ... ...an up and rebuild cities in balance with nature (Merrifield and Swyngedouw, 1997) rather than destroy natural environments. With more and more people living and moving to cities, the problem will extend beyond existing boundaries and result in more damage to the natural environment. The effects of urbanization on the environment are permanent and extensive and urban policy must change in order to save what is left in the natural world. Literature Cited Harms, Valerie. 1994. The National Audubon Society: Almanac of the Environment. G.P. Putnam’s Sons: New York Keller, Edward A. 1996. Environmental Geology. Prentice Hall: Upper Saddle River. Merrifield, Andy and Erik Swygedouw. 1997. The Urbanization of Injustice. New York University Press: New York. Porter, Gareth and Janet Welsh Brown. 1996. Global Environmental Politics. Westview Press: Boulder.
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