The Aral Sea
The sea, which was once famed for its clear water and plentiful supplies of fish, not only shrank (its level fell by 16 metres between 1966 and 1993, and its southern shore-line receded by 80km), but also suffered major pollution.The last of its 20 indigenous species of fish disappeared in 1985.
The surrounding climate has also changed. Winters are colder and a month longer, and summers are hotter. The average number of rainless days has risen from 30 in the 1950s, to 150 today. Salt-dust sandstorms, which pick up chemical residues from cultivated land, are now creating a new desert.
Quite apart from the death of the once-thriving fishing ports, now marooned inland, health problems in the surrounding areas include respiratory illnesses, cancers of the throat and oesophagus, typhoid, and hepatitis.
Infant mortality rates are the highest in the former USSR; in Nukus, capital of the Karakalpak Republic, almost all pregnant women are anaemic.
Remedies being considered do not include restoring the sea - now divided into two - to its former glory. A plan whereby the northern section may reach a new equilibrium by 2025 depends on active support from surrounding governments, which does not look likely.