The Aral Sea, once the fourth largest lake in the world, has been shrinking since the 1960s due to a major water diversion project undertaken by the Soviet Union on the arid plains of Kazakhstan, Uzbekistan, and Turkmenistan. The region’s two major rivers, fed by snowmelt and precipitation in faraway mountains, were used to transform the desert into farms for cotton and other crops. Although irrigation made the desert bloom, it devastated the Aral Sea. The lake was already a fraction of its 1960 extent at the start of the 21st century. The North Aral Sea had separated from the South (Large) Aral Sea. The South Aral Sea had split into eastern and western lobes that remained tenuously connected at both ends. By 2001, the southern connection had been severed, and the shallower eastern part retreated rapidly over the next several years. Especially large retreats in the eastern lobe of the South Aral Sea appear to have occurred between 2005 and 2009, when drought limited and then cut off the flow of the Amu Darya. Water levels then fluctuated annually between 2009 and 2018 in alternately dry and wet years. In 2014, the eastern lobe of the South Aral Sea completely disappeared. The increasingly salty water became polluted with fertilizer and pesticides. The blowing dust from the exposed lakebed, contaminated with agricultural chemicals, became a public health hazard. The salty dust blew off the lakebed and settled onto fields, degrading the soil. Croplands had to be flushed with larger and larger volumes of river water. The loss of the moderating influence of such a large body of water made winters colder and summers hotter and drier. Although climate change has been a contributing factor to the shrinking of the Aral Sea, it is not the primary cause