In the next decade, China hopes to accelerate prosperity expansion. This requires the spread of urbanization from the first-tier cities to the rest of China and a shift to sustainability.

During the 18th National Congress of the Communist Party of China, China's goal became to double per-capita income by 2020. In this challenging task, the key role belongs to urbanization, which is now included in the national strategy.

And yet, recently a significant chunk of China has been shrouded in smog, which has prompted national meteorologists to issue a warning, for the first time.

Is economic development mutually inclusive with sustainability?

No simple models

Due to the extraordinary size of the Chinese population and huge regional differences in economic development, neither the opportunities nor the risks of Chinese urbanization are well understood.

Urban planners in the West are often all too eager to apply their models in China, in spite of huge differences in size and economic development. Some of these models can be very effective in small and medium-sized nations of 5-50 million people. A continental economy of more than 1.3 billion people is a different story. Size matters.

Moreover, most of these models match the needs of advanced economies in which the prosperity is on average around US$30,000-US$50,000 at purchasing power parity, not US$8,400 as in China. And GDP per capita is not just a measure of living standards, but a short-hand for energy intensity. The latter tends to accelerate during industrialization, but decelerates thereafter.

Advanced economies saw the peak of their industrialization more than a century ago. China is still industrializing - particularly in less developed cities and regions.

On the one hand, all emerging economies, including China, seek to complete their industrialization to avoid the "middle-income trap." On the other hand, none can afford to ignore the long-term costs of the corrosive damage that modern growth can bring about.

Megacities in vanguard

China's 11th Five-Year Plan (2006-10) first called for greater efforts to rebalance China's development patterns. Like a handful of other leading megacities, Shanghai drives rapid economic growth regionally, while integrating China into the world economy.

Chinese development relies on the engines of these megacities and their high levels of fixed asset investment and foreign direct investment, their role as trade hubs, rapid restructuring, and high relative levels of per capita consumption.

Now the great challenge in these megacities is to move toward sustainability.

It is not a new goal in China. Since the 1980s, the government has explored many aspects of urbanity, including social ("civilized city"), environmental ("eco-city") and human aspects ("livable city").

However, now that urbanization is seen as a historical task of modernization, a substantial momentum is driving change.