The Copernicus Sentinel-2 mission shows us what is left of the Aral Sea, once the fourth largest lake in the world.

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Straddling the border between Kazakhstan in the north and Uzbekistan in the south, the Aral Sea was once a large inland water body in Central Asia. In 1960, the lake covered an area of about 68 000 sq km – twice the size of Belgium.

Before the 1950s, the Syr Darya and the Amu Darya rivers carried fresh mountain water into this temperate oasis, situated in a mostly arid region. However, in the 1960s, the rivers were diverted to irrigate cotton fields across the region and since then the Aral Sea has shrunk dramatically.

By the end of the 1980s, the Aral Sea had split into two bodies of water – the Large Aral shared by Kazakhstan and Uzbekistan, and a smaller almost unconnected lake to the north, the Small Aral, in Kazakhstan. By 2000, the Large Aral had further split into two.

In this image from 18 March 2025, we can see how the western lobe has reduced substantially, while the eastern lobe, still visible in this image from 2006, has virtually dried up. As the Aral Sea evaporated, it left behind a zone of dry, salty terrain. This appears in the image as a whitish area over the former lakebed, now the Aralkum Desert, Earth’s youngest desert.

The retreat of the waters devastated the area’s thriving fishing industry and altered the regional microclimate. Violent sandstorms have now become an annual occurrence, transporting tonnes of salt and sand from the dried-up lakebed across hundreds of kilometres. This causes severe health problems for the local population and makes regional winters colder and summers hotter.

At the northern tip of the western half of the Large Aral, we can spot the remnant of what appeared as an emerald green heart-shaped body of water in 2019. This water body is also retreating and is likely to disappear soon.

The ice-covered waters of the Small Aral Sea can be seen in the upper part of the image. While the lake’s entire southern section is expected to soon dry out completely, the Small Aral Sea is the focus of international preservation efforts.

The two brown straight lines at the southeastern tip of Small Aral indicate the Kok-Aral dike, which was constructed to prevent water from flowing into the southern section of the lake and to stabilise the water level and salinity in the northern section. Since its completion in 2005, the water level has risen in the northern section by an average of 4 m.

The drying up of the Aral Sea is a striking example of long-term changes – both natural and linked to human activity – that can be tracked by satellites to provide data to help decision-making.