West says all the super-sized cities around the world seem to share this concept of super-linear scaling. “In order to sustain growth,” he says, “you need to continuously innovate and you need to do it at a faster and faster rate. So that the time between major innovations gets shorter and shorter, and the pace of life has to necessarily get faster and faster to sustain that growth.”

While they may share the same principles, the reasons driving them are very different. Each are under different pressures as they struggle to support increasing numbers. Here are five cautionary tales from megacities, that together paint a fuller picture of the consequences of the spiralling urban population.



CAIRO – CONGESTION

Egypt’s capital is home to more than 18.5 million people, and for nearly 10 years, city planners have openly acknowledged a crowding and congestion problem. Just last month, Egypt unveiled plans to solve this massive problem by building a new “nameless Cairo” from scratch to the east of the city, according a recent article in The Guardian. It will cost £30bn and five to seven years to complete; “nameless Cairo” will be some 700 square miles, featuring a park twice the size of New York’s Central Park.

The problem is this type of planning often doesn’t pay any attention to human nature, says urban planner Wendell Cox. “There is a tendency on the part of planners to presume that they can sort of put people in jobs where they want and they’ll stay there,” he says. “But the world is dynamic. So that kind of thinking just doesn’t work.”