By the end of 2008, for the first time in history, half of the world's population will live in urban centers, according to a revised United Nations population study. Barbara Schoetzau reports that the survey also predicts the world's urban population will almost double to 6.4 billion people by the year 2050.
The report's findings imply that urban areas must be prepared to absorb enormous numbers of people over the next four decades. U.N. population officials say the growth of cities will not only be caused by populations migrating from rural areas, but also by the transformation of many rural areas into urban centers.
Hania Zlotnik, the head of the U.N. Population Division, says most of the growth will be in small cities, not the mega cities like Tokyo, New York and Mexico City.
"By small cites, we mean cities with less than half a million people over time. I have to say for the cities that have more than half a million people, we know them by name and address," Zlotnik said. "But for the cities that have less than half a million people we really do not know where they are because they number in the tens of thousands. It is important to understand what you are going to have is birth of new cities. "
Most of the population growth is expected in less developed regions, especially Asia. Due largely to the rapid urbanization of China, Zlotnik says Asia is expected to become 50 percent urban within the next 15 years. Africa's urban population is expected to triple over the next three decades.
Zlotnik says urban centers are viewed as economically dynamic, attracting investment and creating employment. Ironically, improvements in rural areas can lead to population declines.
"Usually rural development implies having agricultural production that is more productive. To do that, you have to have less people producing because the productivity is measured on the basis of how much labor you put in. So you need to become more agribusiness and agribusiness uses less people. So they need to find employment for the excess labor that will be left when that happens," said Zlotnik.
The report represents the first time the United Nation has made urban projections as far ahead as the year 2050. The report is based on continued reductions in birth rates. If fertility rates remained at the current rate, the world population would reach eight billion by 2050.
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经过修订的联合国人口调查报告显示，到2008年底，全世界一半人口将居住在城市里，这是历史上前所未有的。这项调查还预言，到2050年，世界城市人口将是现在的一倍，达到64亿。
多数人口增长将在小城市
这份报告暗示，在今后40年里，城市地区必须准备吸收巨额人口。联合国经济和社会发展部人口司官员说，城市人口增长不仅是因为来自乡村的移民，还因为很多乡村地区变成城市中心。
联合国人口司负责人兹洛特尼可说，大多数人口增长将在小城市里，而不是在东京、纽约和墨西哥城这样的大城市里。
他说：“小城市是指人口不到50万的城市。我可以说，我们知道人口超过50万的城市叫什么，地点在哪里，可是人口不到50万的城市，我们真的不知道它们在哪里，因为那样的小城市数以万计。了解新城市的诞生非常重要。”
城市人口的增长预计大部分发生在不那么发达的地区，尤其是亚洲。兹洛特尼克说，主要由于中国迅速城市化，在以后15年里，预计50%的亚洲人口成为城市居民。非洲的城市人口预计在以后30年里会增加两倍。
农村的改善或导致人口减少
兹洛特尼克说，大城市被认为在经济上非常活跃，能吸引投资，创造就业机会。有讽刺意味的是，乡村地区的改善可能导致人口减少。
兹洛特尼克说：“通常乡村的发展意味着农业生产要更有效率。要做到这一点，必须减少从事生产的人，因为生产力是根据有多少劳工参与生产来衡量的。因此，需要有更多的农业企业。农业企业使用较少的人。因此，当这种情况发生时，会出现多余的劳工，他们需要为这些劳工找到就业机会。”
这份报告是联合国首次对远至2050年的城市人口做出预测。报告是根据出生率继续下降所做的预测。如果生育率维持在目前的水平，世界人口将在2050年达到80亿。
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