West Africa's future MEGALOPOLIS

The stretch of coast between Abidjan in Ivory Coast and Lagos in Nigeria is on course to become the largest continuously populated zone on the planet. But a lot needs to change to help it flourish

- Howard W French

It has long been said that no one knows with any certainty the population of Lagos, Nigeria. When I spent time there a decade ago, the United Nations conservatively put the number at 11.5 million, but other estimates ranged as high as 18 million. The one thing everyone agreed was that Lagos was growing very fast. The population was already 40 times bigger than it had been in 1960, when Nigeria gained independence. One local demographer told me that 5,000 people were migrating to Lagos every day, mostly from the Nigerian countryside. Since then, the city has continued to swell. By 2035, the UN projects that Lagos will be home to 24.5 million people.

What is happening in Lagos is happening across the continent. Today, Africa has 1.4 billion people. By the middle of the century, experts such as Edward Paice, author of Youthquake: Why Africa's Demography Should Matter to the World, believe that this number will have almost doubled. By the end of this century, the UN projects that Africa, which had less than one-tenth of the world's population in 1950, will be home to 3.9 billion people, or 40% of humanity.

These are staggering numbers, but they do not tell the full story. We need to zoom in closer. It is in cities where most of this astounding demographic growth will occur.

Once we begin to think along these lines, what is at stake becomes even clearer. Much western commentary on Africa's population growth has been alarmist and somewhat parochial, focusing on what this means for migration to Europe. The question of how African nations manage the fastest urbanisation in human history will certainly affect how many millions of its people seek to stay or leave.