Tokyo, New York, Shanghai, Bombay… Each of these huge cities already has between 18 and 35 million inhabitants and all of them are located along the coast. But the often anarchic development of these towns, the massive production of waste and untreated wastewater pose serious environmental and health problems. Some of these cities which are near deltas and built on old wetlands are particularly vulnerable in case of natural disasters.
China has plans to build 400 new cities before 2020 and has been testing the prototype of an eco-friendly city which recycles water and energy. This is why at the mouth of the Yang-Tse-Kiang, on the outskirts of Shanghai, Dongtan is the first « green estate ». No building will be higher than 8 floors and the roofs will be vegetalized to insulate the buildings and recycle water.