The Aral Sea
The Aral Sea was once the fourth-largest body of inland water in the world. During the 1960s, Sovietcentral planners diverted two main rivers feeding the sea -- the Amu-darya and the Sir-darya -- to irrigate cotton fields. As a result, Uzbekistan became one of the largest cotton producers in the world. But agricultural success came at a heavy cost -- the sea began to shrink, the local fishing industry completely collapsed, and the region's climate began to change. The air became saturated with chemical dust and salt left behind as the increasingly polluted sea retreated, contributing to the misery of the local population. Ailments -- such as cancer, anemia, and allergies -- became widespread, causing average life expectancy to plummet from 64 years to 51. The Aral disaster has been described as the worst man-made environmental catastrophe of the 20th century.