If you compare maps from last century to today, you can see what was once the World's fourth largest lake has shrunk immensely. Here are some links to places about this phenomenon:
Comparing 5 maps from 1957 to 2001
NY TImes article
Article with time lapse movie
The shrinking of the lake is mostly a result of the diversion of rivers that supplied the Aral Sea, and is essentially the result of humans. Map makes have been having to adjust their maps, and countless case studies have been done.
Many don't realize how much humans are influencing our World until they see things such as the Aral Sea case study.