225 miles upstream from where the Aral Sea once rippled, water splashes from sprinklers, and thick clusters of marigolds and hibiscus are visible in the sandy loam soil. The afternoon ritual that takes place around Urgench allows the 200,000-strong Uzbek city in the middle of the Khorezm oasis to be bathed in flowers until autumn.

Boys use water from the Amu Darya river to irrigate parking lots, and tankers spray the highways to combat dust. Cotton fields stretch to the horizon, fed by a labyrinth of reed-choked irrigation canals.

An abundance of water seems obvious, yet it is an expensive and shrinking resource that is still taken for granted, despite the region being very close to one of humanity's greatest environmental catastrophes – the drying up of the Aral Sea, which was once the fourth-largest lake in the world. Since 1960, 90% of the Aral has disappeared. The sea used to moderate the climate, which is now hotter and drier; storms scatter salt and chemicals into the air. Among the population, anaemia, certain types of cancer, and other health problems are more common.

Although the sea is gone forever, the Amu Darya, one of the two rivers that fed the Aral, is now also drying up, hindering crop growth and affecting millions of people in Uzbekistan and Turkmenistan.

International financial donors are calling for a change in behaviour so that wastefulness caused by climate change does not make western Uzbekistan uninhabitable. The UN Food and Agriculture Organization (FAO) predicts that by the middle of the 21st century, with a growing population, water availability per capita will decrease by 33%. Last year, the World Bank estimated that by 2050, 2.4 million people across Central Asia – 3.4% of the region's population – could become climate refugees.