By the end of this year, over half the world’s population will live in urban areas. It is a trend that is set to continue. By 2050, it is predicted that 70 per cent of the world will be city dwellers; 7 in 10 of us could live in “mega cities”, cities of at least 10 million people.

Some of the fastest growth is occurring in Asia, where mega cities are blossoming, particularly in developing countries.

Take for example Indonesia’s capital Jakarta; its population has risen rapidly from 1.2 million in 1960 to 9 million today, and that is counting just legal residents. By including Jakarta’s sprawling metropolitan area, the population rises to 23 million. And it is still growing rapidly.

Jakarta’s popularity is putting huge pressure on the environment.

Traffic is gridlocked, air quality is at crisis point and Jakarta’s rivers are choked with human waste and garbage. Poor sanitation also creates…