for National Geographic News
Humans are about to become a majority urban species for the first time. Does this trend mean poverty or prosperity for the world's urban dwellers?
A UN forecast released last week reports that half of all humans will live in urban areas by the end of the year—and 70 percent by 2050—even though cities occupy only about 3 percent of Earth's land surface.
Urban growth is driven by the developing world, where African and Asian cities grow by a million people a week, according to the UN Population Fund (UNFPA) report. (See photos of some of the world's most crowded cities.)
Cities are growing, in part, because their large, young populations are in their reproductive prime. But observers note that much urban growth also stems from steady migrations of rural dwellers looking for economic opportunity.
Surging cities in economically challenged nations can present a host of problems.
About a billion people currently live in sprawling city slums with inadequate access to clean water, proper sanitation, or legitimate housing, the report states. That number could double in three decades.
But some experts, including the report's lead author, say urbanization provides valuable economic opportunities.
The historically wealthy nations in Europe and North America, for example, are more than 70 percent urbanized.
"Contrary to what most policy makers have been saying, urban growth can be extremely positive for economic growth, social development, demographic stabilization, and even for environmental issues," said George Martine, a demographer who wrote the UNFPA's recent State of World Population 2007 report.
"But in order for that to happen, we'll need to take a completely different approach from the one that people are taking now."
(See an interactive map of global urban growth.)
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