城市人口爆炸注定要继续下去,这一趋势将贯穿整个21世纪,同时也为科学家们带来了挑战和机遇。在不到一个人的生命周期里,地球的面貌就已经发生了巨大的改变。在1950年的时候,只有29%的人生活在城市里。而如今,这一数字已经达到50.5%,预计到2050年将达到70%。以下一组图片反映了上世纪50年代世界主要城市的人口规模以及未来的预期扩张趋势。 The explosion of the urban population is doomed to continue, a trend that will run through the 21st century as it presents challenges and opportunities for scientists. In less than a person’s life cycle, the face of the earth has changed dramatically. In 1950, only 29% of people lived in cities. Today, however, this figure has reached 50.5% and is expected to reach 70% by 2050. The following set of pictures reflects the population size of major cities in the world in the 1950s and the anticipated expansion trend in the future.