One hour’s drive from Hong Kong takes you to a construction field of reddish brown mud. Here, amid the snaking tracks of dump trucks, men in hard hats discuss the transformation of 15 sq km of wasteland into what’s fast becoming known as the “Manhattan of the Pearl River Delta”.

Qianhai – or, to give it its formal title, the “Qianhai Shenzhen-Hong Kong Modern Service Industry Cooperation Zone” – is the very model of a modern urban centre.

On paper, it looks like something out of Star Wars: an arc of skyscrapers rising from reclaimed coastal lands and standing sentinel round a circular harbour. Wide boulevards and geometric patterns proclaim a sense of order and good governance: a safe place for the world’s capital.

For this has been designated a special economic zone, the site of Shenzhen’s new international finance district by 2020 and a nascent competitor to the global greats of Hong Kong’s Central, Wall Street and the City of London.

“It’s a hot topic of debate whether Qianhai will be in competition with Hong Kong,” says Marcos Chan, head of research for Hong Kong, Macau and Taiwan for real-estate multinational CBRE. “Here we have a big piece of land in Shenzhen with potentially up to some 150 million square feet of office space that effectively transforms it into a new strategic centre for commerce, finance and the professional services. And there are enormous incentives for companies to set up business here.

It’s leveraging on the fact that while it might be physically in mainland China, for the first time ever there’s a chance that Hong Kong’s legal framework can be applied in certain business aspects.”

In the past 12 months, more than 10 sites have been sold and their developers have broken ground.

“These sites are huge in scale,” says Chan, “and as a result developers are often paying very good sums – accommodation values ranging from 8,000 yuan [HK$10,000] to 28,000 yuan per square metre. And it’s not just in Qianhai that we’re seeing interest: there’s anecdotal evidence to suggest that people in Shenzhen are already speculating on the residential properties nearest to Qianhai, even though it’s still pretty much a construction site.”

There’s more to Qianhai than its relative clout as the new kid on the block, however. Its wider importance lies in joining up the dots of the Pearl River Delta, creating the world’s largest conurbation, with a population estimated by the United Nations to be an almost inconceivable 120 million people.

Whereas 200 years ago, just 3 per cent of the world’s population was classed as “urban”, by 2010, this figure had exceeded 50 per cent and, by 2050, more than 70 per cent of us will class ourselves as city dwellers. In what’s widely accepted to be the biggest change ever facing mankind, we are now – de facto – an urban species, with cities not only getting more numerous but also much, much bigger. One in 10 of the world’s population now lives in what is classed as a “megacity” – a city with a population of more than 10 million – but it seems this definition is already too small-scale. In China alone, Beijing and Shanghai are classed as “metacities”, with populations of more than 20 million. But in certain key areas such as the Pearl and Yangtze river deltas, giant cities blend into one another creating an entirely new breed of urban space – no longer megacities but megaregions.

“It’s true: we’re finding ourselves in a territory we’ve not been in before,” says Professor Chris Webster, dean of the Faculty of Architecture at the University of Hong Kong. “Cities are now qualitatively different – they’re an entirely new urban structure. Cities of the industrial era were the classically monocentric, focused around centres of communication, like London or New York, with their train stations. Then, in the last half of the 20th century, you started to get the polycentric city as the dominant urban form. These came about where it was taking over three hours to commute to work – like in Bangkok before the metro and the sky train, where the city was effectively broken down into a number of centres just to make daily life more manageable for its residents.

“But then two things happened: the mega-monocentric cities like Cairo, Tokyo, Istanbul and Mexico City got even bigger, with populations up to 20 million or more, while in the Pearl River Delta and Yangtze, four or five cities each with a core of five to seven million grew into each other – and thus was born something that looked distinctly different from anything else: the megacluster or megaregion.”

Webster has studied new urban forms all over the world.

“Things are changing so fast that – just like official population census figures can’t keep up with the real numbers of immigrants – the theory’s not keeping up with the practice. I tend to class cities as either spontaneous, like Mexico City, that grow by accretion – in spite of government controls – through squatter neighbourhoods, evolving over time into something more permanent and suburban; or planned – for example, the Chinese model, where you design and build a city with all-singing, all-dancing infrastructure going in before the people.

“Which model is best? That’s the big question! Nobody knows! Both can be successful in dealing with this huge rise in urbanisation and both have wastages, but I’m a fan of spontaneous growth, as you get rich and poor living cheek by jowl and it’s often more dense in terms of space. Just look at the wasted space in the hyper-planned Shenzhen boulevard: it’s like the Champs-Elysees but three or four times the width!” And here’s the rub: with space increasingly at a premium, how do cities accommodate their rising populations?

Webster laughs.

“It’s a tough question,” he says. “Some megacities have dealt with their rising populations by retro-fitting new infrastructure to make even more dense use of space, for example, what’s happened around the Erawan Junction in Bangkok, where you now have four or five layers of transport network built within caverns of high-density buildings to cram more in. Alternatively, you get a city like Istanbul, which has just embarked on a process of reorganising 60 to 70 per cent of its housing area in an unbelievable project that will effectively reconstruct a largely spontaneously formed city over the next couple of decades – but for that you need a very efficient and powerful land reorganisation law and a powerful government.”

“It’s very much an Asian-style response to go for high-density urban spaces,” says Professor Johnny Chan, dean of the School of Energy and Environment at City University.

“Unlike in Europe, where there tend to be more planning restrictions on how high and how close your buildings can be, Asia’s cities are often less protected and so they build as high as possible and as close as possible, to maximise the use of space.”

And it seems there are other, less pragmatic factors at play in the brave new mega-urban world.

“You will see more and more super-tall skyscrapers coming up in China as local governments are always proud of having iconic buildings in their cities,” says Marcos Chan. “Metropolitan cities like Shanghai, Beijing and Guangzhou are all having gigantic 500-metre-plus towers coming on stream. Shanghai will even have one exceeding 600 metres. These buildings are all over 100-storeys tall, symbolic enough not just for the cities but also for some of the most sophisticated office tenants in the world – and I see no reason why Shenzhen’s Qianhai would walk away from this development model.”

But what if you’ve gone just about as high as you can?

“Another method, if the city’s on the coast or perhaps an island like Hong Kong, is building into the sea through massive land reclamation projects, or you can go underground,” says Webster. “For the last 50 to 60 years, we’ve been putting the sewerage and utilities, the MTR, car parks and walkways underground, and in the last 30 to 40 years we’ve seen shopping going underground, too, in places like Tokyo, Atlanta and Hong Kong’s Causeway Bay – but why not industry, hotels and restaurants, too?” The most startling example of this subterranean trend is Beijing’s underground bomb shelter development.

“Starting in the centrally planned era, all tower blocks had to have underground bomb shelters – but these were never used,” says Webster. “So in a megacity where rents are sky-high, it’s only natural that these bomb shelters should be used informally by underground squatters: the ‘rat people’ or ‘mouse tribe’, as I like to call them. It’s all very Blade Runner, but a recent conservative estimate from a [Massachusetts Institute of Technology-University of Southern California] study by Professor Annette Kim suggests there are a million rat people living underground in Beijing’s bomb shelters.”

And it’s not just unskilled migrants who suffer the dark side of the megacity, living in ultra-high densities.

Researchers studying the most marginalised groups in Chinese society have found that Guangdong’s so-called “ant tribe” – hard-working, aspirational college graduates with degrees in economics, engineering, management and medicine – are living in slum conditions in overcrowded city apartments just to get a foot on the job ladder.

According to Webster, the ant tribe colonises the highdensity urban villages of both Guangzhou and Shenzhen.

To its embarrassment, Hong Kong is home to possibly 100,000 “cage dwellers”, who pay about HK$1,300 a month to live in the notorious stacks of wire-mesh cubicles, rooftop shacks or heavily subdivided rooms in one of the richest cities on Earth.

“Where does the urban population live when land is congested and prices are way out into the stratosphere?” asks Webster. “They live in spaces not normally considered [fir for a] human. They do it as they’re earning a ‘good enough’ salary – and the government tolerates it to make the city work.

“What is the limit? How low can you go? I once spoke to a family in Shenzhen living on the seventh floor of a self-built house in an urban village – teenage son, mum and dad. Their room is subdivided and it contains a bed and half-a-bed’s space – about three to four metres square … for three people. They have to take turns to sleep. Now that sounds pretty horrific but then add four layers of time-share bunks to that space, to get eight people in a four-metre-square room. I think that’s approaching the limit.”

Webster is now researching the effects of high-density urban living on mental and physical health.

“Anecdotally, we know that your mental health suffers in high-rise living, especially for women, and we also know that it’s not just a cultural stereotype that the Chinese here wear glasses: it’s actually true. Hongkongers suffer from high levels of myopia – possibly because kids here grow up not looking beyond three to four metres or because of poor access to daylight in the city. Most probably, it’s a combination of the two.”

So is urbanisation affecting human evolution? “It might well be,” says Webster. “We already know that your environment has a large impact on your health and the interaction between environment and genetics is a really interesting area that’s now getting a lot of attention.

In fact, at HKU’s Faculty of Architecture and Faculty of Medicine, we’re setting up a global centre for studying this relationship.”

For Johnny Chan, it’s the impact of Asia’s new urbanisation on the environment that causes the most concern.

“Megacities in Asia are very different from [those in] North America and Europe because the population density tends to be much, much higher, especially in countries like China, India, Thailand, Korea and Japan. This gives you enormous problems with issues like pollution. Take, for example, places like Hong Kong’s Nathan Road or Queen’s Road Central – here you get so-called ‘street canyons’, where the buildings run in close parallel on either side of the road, cutting out the light and trapping pollutants.

Add to that Asian people’s love of cars as status symbols and you have real problems with air quality, not to mention traffic congestion.”

However, it’s the double whammy of energy consumption and climate change that Chan feels brings the biggest threat to the long-term sustainability of Asian urbanisation.

“We waste an enormous amount of energy compared with many European cities. Our buildings just aren’t built with energy-saving measures in mind – things like doubleglazing and insulation or even solar power – because they’re costly to install and even if governments impose tight planning regulations, which few seem to do, people often don’t stick to them.

“With climate change, things are only going to get worse.

As it gets hotter, we’ll need more air-conditioning to cool our already inefficient buildings, and that generates yet more CO2 [carbon dioxide], so the cycle continues. But as well as warmer temperatures, climate change also means we’ll get heavier rainfall, so there’s likely to be even more flooding.

The problem with this is that most of Asia’s megacities grew up in the 1980s and 90s with relatively small storm drains that were not designed for the huge sizes they should be now – or for the impact of climate change. So flooding is now a serious concern, especially for those cities building subways – and even more especially for coastal cities that are vulnerable to typhoons and storm surges as well.”

Perversely, however, climate change is also likely to bring more droughts.

“We’re not getting more water but less,” warns Chan.

“This is very important in Asian cities. Think about it: we can live without electricity but we can’t live without water. It’s a big concern with a rising population, more industrialisation and more power production – all of which are more likely to add problems of pollution to an already limited supply.

“All these are really serious issues and governments and planners need to take note as it’s not easy to retrofit this kind of infrastructure into a large city. Hong Kong is now thinking about climate change in terms of flooding and sea-level rise – and in 2012 it passed the mandatory Buildings Energy Efficiency Ordinance in a bid to control CO2 emissions – but, for instance, China, Thailand and Vietnam need to give it some serious thought as it really is a very big problem.

“Likewise, Singapore and Japan are very proactive about harvesting and recycling water and also building desalination plants but these use a significant amount of energy, which brings its own problems.”

For Webster, the answer lies in better forward planning.

“The crucial thing now,” he says, “is to invest in lining up a set of alternative technologies for energy, building, housing and so on, so that when the benefits of going alternative exceed the costs, we are not caught napping. The limits to megacity living are complex, multidimensional and interrelated, so it would be easy to miss the boat without coordinated investment and creative thinking about the future of our urbanised species.”

“I think Asia can solve many of these challenges,” says Johnny Chan. “In terms of renewable energy, there’s a genuine problem with solar and wind power here as the buildings are clustered too closely together so they’re dark and there’s not much space – but you can swap glass walls for ‘building integrated photovoltaics’, or BIPVs, which generate their own electricity while also allowing in light.

“Another way to generate your own power is through small-scale incineration, and this has been quite successful in Japan, Korea and Singapore, with relatively little pollution going into the local environment. You can also use carbon neutral technologies to generate biogas or biofuel from food waste or from agricultural residues for the local generation of electricity. The technology already exists and is being used in places like Taiwan and Japan, but it needs good local organisation and governance to make it more widely used in cities. It would certainly suit places like Hong Kong, though, with its high-density residential areas.

You could collect the waste at source and treat it onsite to generate electricity, thereby solving both the waste and CO2 pollution problems.”

It seems that as our cities – and their problems – get bigger, the solution is actually to think smaller.

“Micro or nano-schemes are the way forward,” says Chan, “decentralised models of local electricity generation rather than the traditional power plants outside the city with all the distribution problems they bring. BIPVs, waste generation, energy efficiency and even residential complexes designed for electric cars – these are just some of the innovative ideas that will help sustain our megacities.

And with many of our megacities being on the coast, we should also be thinking about tidal energy from the sea, as it’s the only renewable source of energy that’s predictable.

But – and this is really important – governments need to both invest in R&D for sustainable technologies and legislate with carrots and sticks to get people to actually use them in practice, to make it all work.”

Ultimately, however, Chan thinks that when the problems of energy, water and climate change become critical, governments and people will be left with no choice but to act.

“I think that as Asia progresses and there’s more education and awareness, people will realise that their current lifestyle is unsustainable. It might be a long process but I’m hopeful that people and governments will wake up and start working together – planning and sharing best practices at the local level and between countries – especially when the problem gets critical.

“Why can Taipei separate and recycle its food waste but not Hong Kong? Why can Hong Kong’s storm drains cope with heavy rainfall but not Shenzhen’s? We need to learn from each other and make people aware that there are options to live well and be sustainable.

“It’s not easy – but it can be done.”