The Aral Sea, situated between Kazakhstan and Uzbekistan in Central Asia, represents one of the most drastic environmental transformations in modern history. Once a vast, thriving body of water, its catastrophic decline over the latter half of the 20th century turned a massive inland sea into a symbol of ecological disaster. The loss of this formerly vibrant ecosystem, which moderated the regional climate and supported thousands of people, demonstrates the profound consequences of large-scale human intervention in natural systems.
The Maximum Extent of the Aral Sea
Before its decline began in the 1960s, the Aral Sea was a truly immense body of water, ranking as the world’s fourth-largest lake by surface area. At its peak, the sea covered approximately 68,000 square kilometers, an area comparable to the state of Georgia in the United States. This immense surface held a total volume of about 1,100 cubic kilometers of water.
The sea was characterized by a relatively shallow average depth, recorded at about 16 meters across its expanse. However, the western shores featured a steep continental slope that descended to the sea’s deepest point, approximately 69 meters. This extensive but shallow basin meant the sea was particularly vulnerable to changes in its water balance.
Engineering Decisions That Drained the Sea
The precipitous decline of the Aral Sea was a direct consequence of massive, centrally planned Soviet-era irrigation projects that began in the 1960s. The primary goal was to transform the arid Central Asian plains into a major agricultural zone, focusing on water-intensive crops like cotton and rice.
The sea’s entire water supply came from two great rivers: the Amu Darya, which fed the southern basin, and the Syr Darya, which fed the northern basin. Dams, reservoirs, and a sprawling network of canals were constructed along both rivers to divert their flow. Much of the water was lost almost immediately, with estimates suggesting that between 25% and 75% was wasted through seepage and evaporation from the unlined, inefficient canals.
This massive and sustained water withdrawal essentially starved the Aral Sea of its inflow. River discharge plummeted from an average of 58.8 cubic kilometers annually in 1960 to nearly zero in some later years. The rate of water level drop accelerated rapidly, falling by 80–90 centimeters per year in the 1980s.
Physical Fragmentation and Current State
As the inflow dropped and evaporation continued, the single body of water fractured into multiple, smaller remnants. The first major separation occurred in the late 1980s, when the Aral Sea split into the North Aral Sea (in Kazakhstan) and the larger South Aral Sea (mostly in Uzbekistan). This split was caused by the drying up of the shallow Berg Strait.
The South Aral Sea continued to shrink and soon divided further into distinct eastern and western lobes. By 2014, the shallower eastern basin of the South Aral Sea had completely dried up, leaving behind a vast desert landscape.
To stabilize and restore the remaining northern portion, Kazakhstan completed the Kokaral Dam in 2005. This structure physically separates the North Aral Sea from the lower-elevation southern remnants. The dam successfully captured the flow of the Syr Darya River, leading to a measurable recovery in the North Aral Sea, often called the Small Aral. Its water level has risen by several meters, and its volume has increased to approximately 27 cubic kilometers. In stark contrast, the Western lobe of the former South Aral Sea remains a hypersaline, isolated body of water, while the eastern basin has been permanently transformed into the Aralkum Desert.
Environmental Consequences of Shrinkage
The rapid desiccation of the Aral Sea triggered severe and widespread environmental devastation. The most immediate impact on the remaining water was a dramatic increase in salinity, which rose from an initial level of about 10 grams per liter to over 100 grams per liter in the residual basins. This extreme hypersalinity destroyed the native aquatic ecosystem, leading to the extinction of many fish species and completely collapsing the local fishing industry.
The receding waterline exposed more than 60,000 square kilometers of former seabed, which quickly became the Aralkum Desert. This new desert floor is covered in a mixture of salt, mineral dust, and toxic agricultural chemicals, including fertilizer and pesticide residues. Powerful dust storms now routinely sweep across this exposed land, carrying millions of tons of this toxic dust over vast distances.
These toxic dust clouds have had profound public health consequences across the region, contributing to high rates of respiratory illnesses, cancers, and other health issues in the local population. Furthermore, the loss of the large body of water has altered the local climate, leading to more extreme temperature swings, with hotter summers and colder winters. The deposition of salt-laden dust on surrounding farmlands has also degraded the soil, making it increasingly difficult to sustain agriculture.