In 1950, there were only two megacities, London and New York, with populations of more than 8m. Tokyo joined them a decade later.

This trio formed the core of what Saskia Sassen, the US sociologist, called the “global cities” – urban centres that asserted their power not through empire but through economic influence. The wealth of the world passed through these cities – even if often only on paper – and they expanded rapidly as people crowded in for a share of the opportunity.

By the start of 2010, Tokyo was top of the list of the world’s largest cities, New York was only just scraping into the top 10, and London had dropped off the bottom. New York will join it in megacity oblivion in less than a decade and, with the exception of Tokyo, every other megacity will be in what is referred to as the “global south”. To earn a place in the top 10, cities will soon need to boast a population of 20m or more. This is a new breed of city – the metacity.

Tokyo can already be classed as a metacity, while eight other emerging markets agglomerations – Mumbai, Shanghai, Jakarta, Beijing and Karachi, all in Asia; São Paulo and Mexico City in South America; and Lagos in Africa – are heading in the same direction. Yet it is Lagos, most of all, that is the urbanist’s bogeyman, a city that forces us to confront fears of what will happen if we do not sort out our cities.

If Tokyo is a shimmering, high-tech, consumerist dream of intensity and density, somehow remaining civilised, polite and eye-wateringly efficient, Lagos has become the cipher for the urban nightmare – a city without structure, infrastructure, social provision, amenities or basic property rights for its citizens.

Yet Rem Koolhaas, an architect and theorist, is less pessimistic. In Lagos, with its teeming, steaming, improvisatory human scrum, he sees a vision of the future.

The megacity of tomorrow, Koolhaas suggests, will be less Tokyo and more Lagos. It will be a place of life lived in the margins, where citizens have to work to carve their niche in a city that does not care. And although the dysfunctional image of Lagos radically alters the way we may think about the megacity of the future, it remains only one projection – a worst-case scenario.

The contemporary vision of the megacity still derives from a medieval model, whether in the high rises of Manhattan or the intense activity and constant adaptation of London. Confined within the memory of its Roman walls, we still think of the city as a dense, defined centre, surrounded by a halo of low-rise suburbs. This, though, is the city of history.

As long ago as the 1960s, Yona Friedman, an architect and theorist, predicted the future of the city was not the traditional model but rather a transnational band of contiguous urbanisation. He predicted a European metacity, spreading from Oxford through London, northern France, the Benelux countries and the Ruhr valley.

Ironically, the suburban growth of the cities in this belt, which has coincided with the decline of heavy industry, infrastructure developments such as the Channel Tunnel and city-scale airport hubs, as well as government-sponsored schemes such as the UK’s Thames Gateway and Germany’s Emscher Park, may be making Friedman’s vision a reality.

North-western Europe has become a de facto metacity, and a successful one at that, thanks to its infrastructure. Exemplary public transport and communications as well as, by and large, governance have allowed the region to manage the decline of traditional industry through the expanding knowledge economy and the growth of finance. It is supremely connected in every possible way, and in this it shows the future.

The physical scale of the metacity means that, to function, its components, which will probably include a series of smaller cities and subsumed former suburbs, will need connectivity. Digital networking has not, as was forecast, led to a decline in the city. Rather, it has led to an urbanisation of the rest of the planet.

The US east coast, encompassing Boston, New York, Philadelphia and Washington, DC, shows the way to a different agglomeration – one that is connected by motorways and airports rather than trains, but also one that continues to suffer severe problems in the hearts of its component cities.

In Asia, another astonishing model has emerged: China’s Pearl River Delta. Blending the ad hoc industrial sprawl of the world’s manufacturing base with the hyper-density of Hong Kong, it is home to a population of more than 40m.

The compact, walkable, historic European city remains a planner’s idyll. Yet it can seem that, in spite of the best intentions, it is the incoherent, urban sprawl of Los Angeles that points to the future as emerging economies grow and look longingly upon the Hollywood lifestyle.

Southern California, from Los Angeles to San Diego, has become a vast, dispersed city of smeared suburbs, strip developments and gentrified but sparsely inhabited downtowns. It bursts across the Mexican border into Tijuana, which has become, in effect, its transnational suburb.

Teddy Cruz, an architect who has spent his career working on the California/Mexico border, points out that cities such as Tijuana have developed their own sophisticated informal urbanism.

In contrast to the uniform, dim developers’ boxes that carpet California, Tijuana’s shantytowns are given architectural character through their reuse of discarded building components and their residents’ enforced ingenuity.

While California adheres to modernist-sanctioned zoning – the separation of commercial, industrial and residential functions – Tijuana revels in a celebration of density. It is here that Cruz makes his sharpest observation. In the traditional European city, density is gauged by inhabitation. Cruz, however, suggests density should also be a measure of intensity – a density of social and economic transactions, which he believes is the real measure of city success.

It is Tijuana’s informal density – the creation of close-knit networks and communities with very limited means – that creates such a severe contrast with its affluent neighbours.

And while no one is suggesting that Lagos or Tijuana are paradigms for the modern city, both create genuine urban activity of a vibrancy and self-sufficiency that seems to elude the west.

Where they collapse is in equality – which represents one of the biggest crises facing the metacity. Studies consistently show that wellbeing is commensurate with a relatively equal society. Yet the emerging megacities – from Mumbai to São Paulo – accommodate extreme asymmetries of wealth.

In these conditions, the wealthy begin to fear while the poor become envious. The result is ghettoised cities in which walls and gates become the norm as communities, often in close physical proximity, vie to exclude the other.

These are among the gravest problems facing the metacity. Their size and scale of growth make governance difficult, while exploitation through accommodation becomes endemic. Inequality can become engrained and, while western cities may have solved some of the problems, the particular mix of wealth and further immigration from poorer countries may once again increase inequality.

What hope is there for the exploding metacity of the global south? How can growth at this scale be made sustainable?

Sustainability has become a cliché. Cities are pilloried for their profligacy with energy and resources as they are contrasted with the sentimental image of an ancient rural lifestyle.

In fact, the opposite is true. The least “green” areas of the UK, for instance, are the thinly inhabited rural areas of the north, while the concentration of resources in London makes it energy efficient, its populace relying on public transport and legs, its services, workplaces and shops still (relatively) local.

Yet Anglo-Saxon culture seems to have developed a fear of the city, which is still resulting in a ceaseless race for suburbia. The metacity of the global north remains less hyper-urban than super-suburban, and that is the model to which embryonic global cities aspire.

The suburb may be the manifestation of a desire to escape, yet the city is itself a traditional response to crisis – a huddling together of humanity, a symbol of hope for a better life, a pooling of natural and intellectual resources.

It is impossible to predict the challenges that will face the city of the future. There will be problems of inequality, health, education, crime, governance, disenfranchisement, terrorism, war and loneliness. But there are other potential nightmares. Food, water, power and air are by no means guaranteed in a future defined by climatic catastrophe, pollution and massive overcrowding.

The metacity puts immense strain on its surroundings, stripping the land of its resources, which ensures further immigration to the centre.

In spite of the nightmare scenarios, it is important to remember that London, the original megacity, has already survived these tribulations and it remains a desirable place to live. None of these problems is insoluble and the city remains, on the whole, a civilising place.

Get alerts on Terrorism when a new story is published

Copyright The Financial Times Limited 2019. All rights reserved.
Reuse this content (opens in new window)

Comments have not been enabled for this article.

Follow the topics in this article