Study: Earth's 4th largest lake shrinking

LONDON, April 17 (UPI) -- British scientists have determined the Aral Sea is drying so rapidly it has shrunk by two-thirds in fewer than 50 years.

The University College London study shows the shrinkage has left two separate lakes where the world's fourth largest lake once existed. And researchers say humans -- including Genghis Khan and the White Huns -- have negatively affected the lake's fortunes for centuries.

Patrick Austin and Anson Mackay of the college's Environmental Change Research Center deduced changes in the Central Asian lake by investigating changes in fossils and the chemical makeup of the water.

They determined the current regression is largely due to the diversion of the Amu Darya and Syr Darya -- one of the irrigation strategies of the former Soviet Union that has led to the loss of 90 percent of the lake's fish species and more than 250 species of plankton.

The study, conducted with colleagues from Kazan State University and the University of Nottingham, appears in this month's issue of the journal Quaternary Research.