Here comes the megacities

By 2100, at least 10 cities are predicted to have population over 50 million. How can society keep pace?

By John Vidal
Published: Monday 16 April 2018

If we get urbanisation right there is real hope that climate change can be controlled.The 1960 street map of Lagos, Nigeria, shows a small coastal city surrounded by a few semi-rural African villages. Paved roads quickly turn to dirt, and fields to forest. There are few buildings over six floors high and not many cars.

It’s likely no one foresaw what would happen between 1960 and today. In just two generations Lagos grew 100-fold, from fewer than 200,000 people to nearly 20 million. Today it is one of the world’s largest cities, sprawling over nearly 1,000 square kilometers (400 square miles). Vastly wealthy in parts, it is largely chaotic and impoverished. Most residents live in informal settlements, or slums. The great majority of them are not connected to piped water or sanitation. The city’s streets are choked with traffic, its air is full of fumes and it produces more than 10,000 metric tons (11,000 tons) of waste a day.

But new research from Canadian academics, though replete with caveats, suggests that the changes Lagos has seen in the last 60 years may be nothing to what may take place in the next 60 years. If Nigeria’s population continues to grow and people move to cities at the same rate as they are moving today, Lagos could be the largest metropolis the world has ever known, home to up to 100 million people. By 2100 it is projected to have more people than California or Britain today, and to stretch hundreds of miles with enormous environmental effects.

In the 1960s, the Nigerian city of Lagos was home to a few hundred thousand people, many living in modest circumstances. Today gleaming skyscrapers dominate the view, and the population has soared to nearly 20 million. Photos courtesy of The National Archives UK (left) and © iStockphoto.com | peeterv (right)

Hundreds of far smaller cities across Asia and Africa could also grow exponentially, say the Canadian demographers Daniel Hoornweg and Kevin Pope at the Ontario Institute of Technology. They suggest that Niamey, the barely known capital of Niger — a west African country with the highest birth rate in the world — could explode from a city of around 1 million people today to be the world’s seventh largest city with 56 million people in 2100. Sleepy Blantyre in southern Malawi could mushroom to the size of New York City today.

Under the researchers’ extreme scenario, where fertility rates remain high and urbanization continues apace, within 35 years over 100 world cities will have populations larger than 5.5 million people. By 2100, say the authors, the world’s population centers will have shifted to Asia and Africa with only 14 of the 101 largest cities then in Europe or the Americas.

This home in the Makoko neighborhood of Lagos illustrates a fundamental challenge of today: As cities boom, how can we meet the basic needs of the individuals and families who make up their millions? Photo courtesy of Heinrich-Böll-Stiftung

Cities in the Global South are growing much faster than they did in industrialized countries 100 or more years ago for several reasons. Fewer children now die young. Migration from rural areas is speeding up because there’s less new farmland to be opened up. Many countries encourage urbanization to grow their economies. As a result, cities today are being challenged to keep pace with the largest wave of urban growth in history and the need to provide water, sanitation and power to all those people.

It’s impossible to know how cities will grow, but the stark fact, according to the United Nations, is that humanity is young, fertile and increasingly urban. The median age of Nigeria is just 18, and of all Africa’s 54 countries is under 20. The fertility rate of the continent’s 500 million women is 4.4 births; meanwhile, 50 percent of India’s population is under age 25, and Latin America’s average age is just 29.

Recent U.N. projections expect the world’s population to grow by 2.9 billion — nearly that of China and India today — in the next 33 years and possibly by a further 3 billion by the end of the century. By then, says the U.N., humanity is expected to have developed into an almost exclusively urban species with 80 to 90 percent of people living in urban areas.

The Canadian researchers observe that urbanization can have environmental benefits in the form of economies of scale; that it is associated with better access to education and health care; and that it can boost the economy. But they also note that cities can become more vulnerable as they grow. And, says Robert Muggah, research director of the Igarapé Institute in Rio de Janeiro, a global think tank, urbanization can rapidly outpace society’s capacity to accommodate it.

“Cities are generating a challenge on a level never seen before.” — Robert Muggah

“Many fast-growing cities urbanize before they industrialize,” Muggah says. “It took centuries for cities in the Global North to do this. In the south we are seeing a doubling of population in 25 years. Most cities [today] don’t have the infrastructure, employment base or productivity to manage this growth. You see a maze of informal settlements, completely overloaded infrastructure. Cities are generating a challenge on a resource level never seen before. The fastest growing cities may be hit the hardest.”

Whether the world’s major cities develop into endless, chaotic slums, with unbreathable air, uncontrolled emissions, and impoverished populations starved of food and water, or become truly sustainable depends on economies, technology and how they respond to population growth and environmental risk.

While many economists argue that population growth is needed to create wealth and that urbanization reduces environmental impact, others fear cities are becoming ungovernable and too unwieldy to adapt fast enough to rising temperatures and sea levels, pollution, water shortages, and ill health of inhabitants.

Will mega-cities be part of the problem — or the solution? What can they do to maximize the benefits of urbanization while minimizing the downsides? This look at seven cities on five continents, each at a different stage of development, can shed valuable light on what it might take to do it right.


Economy v environment 

“This city was renowned for its trees, lakes and pleasant air only 25 years ago. Now it’s a dead city that has sacrificed its environment for some of the fastest economic growth seen anywhere in the world,” says T.V. Ramachandra, head of the Energy and Wetlands Research Group at the Indian Institute of Science.

Ramachandra and colleague Bharath H. Aithal have documented the environmental effects of breakneck urban growth. “Temperature in the city has increased by 2 to 2.5 °C [3.6 to 4.5 °F] and now reaches 38 to 40 °C [100 to 104 °F]. The water table has declined from 28 meters [92 feet] to 300 meters [984 feet] deep in places; there has been an 88 percent decline in vegetation, a 79 percent decline in wetlands. There is now frequent flooding, even during normal rainfall.”

Ramachandra fears that what has happened to Bangalore will happen to all Indian cities.


Satellite photos taken 15 years apart show how houses and businesses have replaced wetlands and other open spaces in Bangalore. Images created from Google Earth Historical Imagery.

“Air pollution is at dangerous levels, the water is polluted, there is nowhere for the waste to go, and the lakes have been killed,” he says. “The situation is very worrying. People are moving out. Illnesses are increasing. At this rate every house will need a dialysis machine. Bangalore cannot continue like this. It is becoming an unlivable city. This is the worst city in the world for unchecked urbanization.”

India, which is widely expected to be the most populous country in the world with over 1.5 billion people by 2050, is projected by government to see its urban population double to nearly 600 million in 30 years. Its megacities, like Mumbai and Delhi, are not expected to grow much more; instead, smaller cities are rapidly expanding.

The environmental cost is huge. India’s air pollution is now as bad as China’s, with 1.1 million people dying prematurely in 2015 alone from poor air quality linked to the hyperdevelopment taking place in many cities. And the “frenzy of unplanned urbanization has divided people and wrecked nature,” says Prerna Bindra, author of The Vanishing: India’s Wildlife Crisis, a new analysis of the effect of urbanization and economic growth on India’s rich wildlife.

“In 20 years the area covered by Indian cities has expanded by a whopping 250 percent … and in the next 15, over 300 million people will be crowding urban India,” Bindra says. “Wetlands, lakes, green spaces are giving way to glass and concrete. The retreat of natural habitats has meant the rapid decline of urban wildlife, even the once ubiquitous: house sparrows or bullfrogs and common toads that serenaded the monsoons; or jackals, once not a very uncommon sight on urban fringes.” Wildlife sanctuaries and national parks are being decimated to make way for roads, housing and industry.

As Bangalore expands into natural spaces, wild animals are increasingly injured, killed or crowded out. Photo courtesy of People for Animals Bangalore | YouTube

In the past 30 years numerous citizen groups and nongovernmental organizations have been established to promote more sustainable development, including improving solid waste management policy, advancing mass transit and promoting urban green spaces. India’s dash for urbanization is lifting people from poverty, but the toll on forests, wetlands and the natural world is vast.

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