More than half of the earth’s wetlands have disappeared since 1900.4 Central Asia’s Aral Sea was once the fourth largest freshwater lake in the world. In the last 30 years, it has shrunk to the size of Lake Michigan, due to pollution and water diversion for irrigation. As it receded, it became saltier and exposed now-polluted land, resulting in food shortages, rises in infant deaths and decreased lifespans.5