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Although there is a long history of human settlement in coastal zones, until the 20th century, the level of disturbance to natural processes did not appear to be critical. During the 20th century, coastal populations grew rapidly around the globe because of the many economic opportunities and environmental amenities that coastal zones provide (Turner and others 1996). Low-lying areas near coasts now have the largest concentrations of people on earth (Small and Cohen 1999). The population in the “near-coastal zone”(defined as areas both within 100 meters elevation and 100 kilometers distance of the coast) in 1990 was estimated at 1.2 billion (thousand million), or 23 percent of the world’s population (Nicholls and Small 2002). Nicholls and Small (2002) also showed that most of the near-coastal zone is sparsely inhabited, with the human population being concentrated in a few specific areas of the world’s coast. These areas correspond mainly to near-coastal plains in Europe and parts of Asia, and to a lesser extent to densely populated urban areas. Hence, there are wide variations in coastal populations among nations. In many small island nations, all land suitable for human habitation is coastal and also in some large countries, most or all major urban centers are located near the coast (eg, Australia). In other countries, such as Mexico, Colombia, Russia, and Iran, many larger cities are found further inland, in spite of the countries’ long coastlines. The United Nations medium projection for population growth suggests that the world’s population will reach 7.2 billion by the year 2015, 7.9 billion by 2025, and 9.3 billion by 2050 (2000: 6.1 billion …