U.N. Predicts Urban Population Explosion

Report Finds 5 Billion Will Live in Cities and Towns by 2030

Pius Utomi Ekpei/Agence France-Presse Vendors sold wares last month in Lagos, Nigeria, one of only two cities of more than 10 million people that are expected to grow at rates exceeding 3 percent over the next 10 years. The other is Dhaka, Bangladesh.

By next year, more than half the world’s population, 3.3 billion people, will for the first time live in towns and cities, and the number is expected to swell to almost five billion by 2030, according to a United Nations Population Fund report released yesterday.

The change is expected to be particularly swift in Africa and Asia, where between 2000 and 2030 “the accumulated urban growth of these two regions during the whole span of history will be duplicated in a single generation,” says the report, “State of World Population 2007: Unleashing the Potential of Urban Growth.”

This surge in urban populations, fueled more by natural increase, or births, than the migration of people from the countryside, is unstoppable, George Martine, who wrote the report, said in an interview.

Cities are predicted to edge out rural areas in more than sheer numbers of people. Poverty is increasing more rapidly in urban areas, and governments need to plan for where the poor will live rather than leaving them to settle illegally in shanties without sewerage and other services, the United Nations report says.

In Latin America, where urbanization occurred earlier than in other developing regions, many countries and cities ignored or tried unsuccessfully to retard urban growth.

“Now the levels of insecurity and violence are a product of this approach,” said Mr. Martine, a Canadian demographer and sociologist. “People have been left to fend for themselves and have created these enormous slums.”

Rather than just letting slums spring up, governments need to anticipate the expanding ranks of the urban poor and provide them with secure housing, water, sanitation and power, among other services, the report says. With decent housing and basic services, the poor can take advantage of the opportunities offered by city life, it says.

A billion people, about a sixth of the world’s population, already live in slums, 90 percent of them in developing countries. In sub-Saharan Africa, more than 7 in 10 urban dwellers live in a slum, an area lacking services such as water, sanitation or legal rights to housing. The region’s slum population has almost doubled in just 15 years, reaching 200 million in 2005. Its urban population is already as large as North America’s.

In China, the world’s most populous nation, urbanites are expected to outnumber people in rural areas within a decade. China would then have 83 cities with more than 750,000 residents, but only five with a population of more than five million, the report says.

In fact, it predicts that the bulk of the urban population growth will be in smaller cities and towns, not the 20 megacities that dominate the public imagination. The future lies in places like Gabarone, Botswana, where the population is projected to reach 500,000 in 2020, up from 18,000 in 1971, as much as it does in chaotic, sprawling metropolises like Lagos, Nigeria.

Among the megacities with populations of more than 10 million, only Lagos and Dhaka, Bangladesh, are expected to grow at rates exceeding 3 percent over the coming decade. Such supersize cities today contain 9 percent of all urban inhabitants, while cities and towns of fewer than 500,000 account for more than half. “Many of the world’s largest cities — Buenos Aires, Calcutta, Mexico City, São Paulo and Seoul — actually have more people moving out than in, and few are close to the size that doomsayers predicted for them in the 1970s,” the report says.

The report notes that while rates of urban growth have slowed in most regions of the world, the story now lies in the expected growth in the sheer numbers of people through natural increases and migration from rural areas.

The first great wave of urbanization unfurled over two centuries, from 1750 to 1950, in Europe and North America, with urban populations rising from 15 million to 423 million. The second wave is happening now in the developing world. There, the number of people living in urban areas will have grown from 309 million in 1950 to an expected 3.9 billion in 2030. By 2030, developing nations are expected to have 80 percent of the world’s urban population.

If this population growth is helter-skelter, with inadequate services and sprawling slums, it could pollute urban watersheds with untreated sewage and contribute to increases in crime and violence, Mr. Martine said. The result of that approach is apparent in today’s slums.

“The poor settle in the worst living space, on steep hillsides or river banks that will be flooded, where nobody else wants to live and speculators haven’t taken control of the land,” he said. “They have no water and sanitation, and the housing is terrible. And this situation threatens the environmental quality of the city.”

But cities are also engines of economic growth, the report notes more optimistically. “Cities concentrate poverty,” it said, “but they also represent the best hope of escaping it.”

Copyright 2007 The New York Times Company. Reprinted from The New York Times, International, of Thursday, June 28, 2007.