New strategy for China's big cities

The nation needs a new prescription for growth: Cram even more people into the pollution-ridden megacities of Beijing, Shanghai, Guangzhou and Shenzhen.

While this may sound like a recipe for disaster, failing to expand and improve these urban areas could be even worse. That's because the biggest cities drive innovation and specialization, with easier-to-reach consumers and more cost-efficient public transport systems, according to Yukon Huang, a former World Bank chief in China.

He estimates China's leaders' seven-month-old urbanization blueprint, which aims to funnel rural migrants to smaller cities, will slice as much as a percentage point off gross domestic product growth annually through the end of 2020.