The Environmental, Social, and Health Dimensions of Urban Expansion
In the coming decades, the world’s rapid urbanization will be one of the greatest challenges to ensuring human welfare and a viable global environment. According to current estimates, cities occupy 4% or less of the world’s terrestrial surface, yet they are home to almost half the global population, consume close to three-quarters of the world’s natural resources, and generate three-quarters of its pollution and wastes. Moreover, the UN estimates that virtually all net global population and economic growth over the next 30 years will occur in cities, leading to a doubling of current populations. This growth will require unprecedented investment in new infrastructure and create undreamed of challenges for political and social institutions. Nowhere are the opportunities more promising or challenges to sustainability more daunting than in the rapidly urbanizing regions of the world. These transforming cities represent the engines of growth for the developing world and, in all regions, will continue to be the centers of innovation, culture, and the arts. These same cities, however, are the loci of increasing poverty, pollution, disease, political instability, and social inequality. The transformation of surrounding land due to urban expansion and urban dwellers ever-increasing demand for energy, food, goods, and other resources is behind the degradation of local and regional environments, threatening basic ecosystem services and global biodiversity.