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At the time of writing (2004), the Aral Sea, formerly one of the largest lakes on Earth, an oasis surrounded by Central Asian deserts, has lost 75% of its surface area and about 90% of its water. The newly dry bottom occupies an area exceeding the territory of Belgium in a remote region of Kazakhstan and Uzbekistan, now independent republics of the former Soviet Union. Aralsk and Muynak, busy and wealthy harbor cities of the 1950s, are now located tens of kilometers away from the present shoreline. A fleet of fishing and cargo ships which once cruised the brackish Aral Sea waters, now rests on the former bottom, quickly disappearing under rust, salt, and sands. Only a few decades ago, biological communities of the Aral Sea and the adjacent deltaic areas included hundreds of species, some of which were endemic. Fishery yields were as large as up to 50,000 tons per year, making up a considerable part of the fish catches of the USSR. For example, the Aral Sea accounted for up to 13% of sturgeon catches. The cargo freight turnover was over 200,000 tons per year. By the 1980s, commercial fishery and navigation had ceased completely, as efforts to keep the ports open became too difficult and expensive (e.g., Micklin, 2004).

We begin with an overview of the paleovariability of the Aral Sea and its regressions and transgressions in the distant past, and then discuss the historical background focusing on human activities in the Aral Sea region and exploration of the lake. Either subject has been discussed in detail in the broad literature, and we restrict this chapter to only an introductory account.

In this chapter, we give a summary of the physical state of the Aral Sea prior to the shallowing onset in 1961. Although we use the present tense throughout the chapter for convenience, the figures and the data presented in this chapter refer to the period from 1911, when instrumental measurements in the Aral Sea began on a more or less regular basis, through to 1960. The drastic changes which have occurred after 1960 are addressed in Chapter 3.

We now proceed to describing the present-day Aral Sea. Here, the present may be understood in a broader sense as the period after the early 1960s, when the desiccation processes had begun, but a special focus is made on the physical state of the lake in the last few years.

It is of obvious practical importance to predict the future changes of the Aral Sea level. The future developments, however, will depend on a number of “external” factors whose future behavior is hard to foresee. We have little means to predict the forthcoming interannual to decadal-scale climate changes modulating the river discharges into the Aral Sea and the evaporation from the lake surface. On the other hand, the forecast can be obtained in the measure that is determined by intrinsic dynamical properties of the system. Therefore, in this chapter, we do not aim at formulating any “deterministic” prediction—rather, we focus on analyzing the mechanisms that would favor one or another future scenario.

The desiccation of the Aral Sea is considered to be among the worst disasters of its kind on record. However, the global list of water bodies experiencing significant desiccation, or otherwise endangered because of either unsustainable anthropogenic pressures or global climate change, is long. The negative consequences are manifold, ranging from deterioration of environmental conditions (desertification processes, increase of climate continentality) to economical and social impacts (decay of fisheries, tourism, and other related businesses). Because the Aral Sea represents an extreme case of lake degradation, insight obtained from Aral may have a broader applicability to other water bodies.

The Aral Sea has lost about 3/4 of its area and nearly 9/10 of its volume since 1961. Simultaneously, the salinity of the lake’s waters has increased by about an order of magnitude (except in the Small Sea, the northernmost portion of the lake that detached from the main part in 1989), which ranks present Aral among the saltiest large inland water bodies on earth. Although the catastrophic shallowing was triggered by a local forcing, both anthropogenic and climatic, the desiccation can be viewed as another striking manifestation of worldwide trends of global change, given that a large number of other lakes and even marine and oceanic regions have experienced environmental challenges of a kindred nature in the 20th century.