One in six of the world's population lives in China. More and more of these people are moving to the cities, as the country's industry grows to meet its needs. Increasing amounts of water and energy are needed to support them.

How the country can do this in a manageable way is a huge question. Can it be done without massively adding to global warming? What will climate change mean for water and food supplies for these people? Once controversial solution has been to build the world's largest dam project on the Yangtzi River: the Three Gorges Dam.