The security of cities: development, environment, and conflict on an urbanizing planet
Humankind recently crossed an important threshold: over half of all people now live in cities. In contrast to most of human history, cities have become the default condition for human habitation almost everywhere on earth. Urbanization is proceeding rapidly and at unprecedented scales in Asia, Africa, and the Middle East. Urbanization in Latin America has already reached levels rivaling Europe, North America, and Australia. These trends are ongoing. By 2030, all of the world's developing regions, including Africa, will have more people living in cities than in rural areas. Between 2010 and 2050, the world's urban population is expected to grow by 3 billion people-a figure roughly equal to the world's total population in 1950-with the great majority of these new additions living in developing-world cities.