It took all of human history to accumulate 3.5 billion urban dwellers on Earth, but it'll only take another 30 years to double that number, a U.N. agency focusing on cities announced Monday.
Although the rate of population growth is decreasing, the U.N. projects that the global population will increase from 7 billion to 9 billion within the next 30 to 40 years, with urbanites growing exponentially. But don't expect to see that impact in your city. Developing countries are expected to represent 96 percent of the urban growth.
"This is why we are very worried, because the number of people living in slums is increasing," Joan Clos, executive director of the U.N. human settlement program UN-Habitat, told the Associated Press.
UN-Habitat estimates that that the world's slum population has increased by 213 million people since 1990, reaching 863 million in 2012—more than twice the entire population of North America in 2010.
Urban immigration is a double-edged swords in the developing world. Although people have experienced improvements in their living conditions, cities experience huge demands on land, resources, and services from handling millions of new arrivals.
In April, 10,000 ministers, mayors, academics and representatives from business, non-governmental organizations and local authorities are expected to attend the World Urban Forum in Medellin, Colombia, to address these issues.