Geologist Liviu Giosan, from the Woods Hole Oceanographic Institute, said large areas of the deltas home to large Asian cities will be under water in 100 years.

Giosan said that if the international community fails to make efforts to protect the environment, important cities like Shanghai (in China, with more than 20 million inhabitants), Dacca (in Bangladesh, with seven million people) and Bangkok (in Thailand, 6.3 million) will disappear.

Giosan and colleagues explained that the deltas form from deposition of sediment carried by a river as the flow leaves its mouth, but the mining of natural resourcdes and water power have cut the rates in the flow of sediment in a way that they may be flooded in the next century.(KH)