The Aral sea was once the fourth largest sea in the world. Today, it has shrunk down to less than 10% of its original size. The shrinkage of the Aral Sea has mainly been caused by reckless human actions and ignorance of the consequences for certain actions. The freshwater sea continues to shrink today and is considered "one of the very greatest ecological problems of our century".
Collaboration between me and @eliseyzhukovsky