These two images, taken in 2006 [left] and 2009 by the European Space Agency's Envisat satellite, show the rapid loss of water in central Asia's Aral Sea, which is shared by Kazakhstan and Uzbekistan.

Decades ago, the sea was the world's fourth largest body of inland water, but diversion of rivers for irrigation has been rapidly shrinking the sea. Two decades ago, it split into the small northern and larger southern sections, and further divisions have been happening ever since.

Kazakhstan and the World Bank partnered in 2005 to build a dike separating—and possibly saving—the northern parts of the sea, But at the current rate, the whole southern segment will likely be bone-dry by 2020.

Aside from lost shoreline, the sea's retreat has also created a new and dangerous feature in the landscape: the Aral Karakum Desert, a salty wasteland that is prone to sandstorms. High winds move about 150,000 metric tons of salt annually, which can harm people and change weather patterns (intensifying seasonal temperature differences).