Here is the famous Steppe, the dry grass-land, the never-ending plain stretching across Eurasia from China to Hungary. Rainfall is too limited for trees to grow. The climate is harsh, with hot summers and cold winters. But this hostile land can make a good living for those who know where to find water. It was once a highway into Europe, used by the many invaders. Genghis Khan came this way. So did invaders of other types: the language, the apples and the horses. There are other steppes in the world. The American prairie is one; the South African veld is another. But none are as large or as famous as the Steppe. It is also known as the Great Steppe, but that distinction is not really needed. A single capital suffices.

The part of the Steppe between the Ural and China is known as the Kazakh Steppe. The historic trade cities of Tashkent and Samarkand are found here. Horses were first domesticated on the Kazakh Steppe, although precisely where and when is disputed: genetic evidence puts it as recent as 2000 BC. The climate here is dry, and the land in places verges on desert. It is kept alive by rivers coming from famous mountains to the south, the Pamir and the Tian Shan. These are among the tallest mountain chains in the world; their rivers provide corridors of water in a hostile land.

The Steppe and the Sea

Steppes of all kinds are found deep in the interior of continents. They are children of continental climates, far from the moderation and moisture from the seas. But water finds its way. Rivers in flat plains can reach dead ends, and form lakes. These lakes can grow to large sizes and attract life. The Kazakh Steppe contains many such lakes, from Lake Balkash in the east to Sarygamish Lake in the west and that ultimate of lakes, the Caspian Sea. A lack of outflow has left them brackish. And among them lies what is perhaps the most famous of the Steppe lakes: the Aral Sea. 400 by 300 km in size, it was once known as the jewel of Asia.

(When is a lake a sea? Size matters, of course. The Aral Sea is 300 km across. But Lake Balkash is 600 km long and did not get the upgrade. Both Aral and Balkash are saline, so that is not the difference. Lake Balkash is narrower, and in most places it is possible to see the opposite shore. The Aral Sea is also four times larger than Lake Balkash in surface area. But if those are the ultimate distinctions between a lake and an in-land sea, why is the Dead Sea a sea? It is only 15 km wide, after all, with a surface area 25 times smaller than Lake Balkash. The Dutch, with their love-hate relation with the sea, managed to turn one of their seas into a lake, twice as wide and twice as large as the Dead Sea, complete with the change of designation.)

(For those interested in trivia, there is one sea without any shore (the Saragasso Sea), and there are 22 seas (and one ocean) entirely devoid of water: look up and see the mares of the Moon.)

But in just the past 50 years, the jewel has lost its sparkle. The Aral Sea went from the third largest lake to a puddle and now to a desert. Only a few slivers survived in the largest ecological catastrophe of the 20^th century.

The region

Geography can be complicated. All this used to be part of the Soviet Union. When the Union collapsed, the area re-emerged as a collection of ‘stans’. The largest of these by far is the nation of Kazakhstan. It is the 9^th largest country in the world and has become the buffer between Europe and China. To the south are Turkmenistan, Uzbekistan, Kyrgyzstan and Tajikistan. Together, these five nations share the Kazakh Steppe. The Aral Sea is on the border between Kazakhstan and Uzbekistan. It is also midway between Russia and Iran, and between the Caspian Sea and China.

The Kazakh Steppe is bordered to the south by large mountain chains: the Tian Shan (’Heavenly mountains’) in Kyrgyzstan and China, and the Pamir mountains in Tajikistan. The Kopek-Dag mountains in Iran and the mountains of northern Afghanistan complete the southern boundary. The Kazakh Steppe forms a lowland against these mountains. To the north the land rises again to become the Kazakh Uplands.

(There are no volcanoes in this post. If you want one, the nearest major volcano is Mount Damavand in the Iranian mountains south of the Caspian Sea.)

The lowlands are not a continuous band but are divided into several depressions. The area north of the Caspian Sea is called (of course) the Caspian depression. The Aral Sea is located in the ‘Turan Lowland’ or ‘Aral Sea Basin’ which stretches from close to the Caspian Sea to the Tian Shan mountains. Lake Balkash lies in a separate depression. Tectonically, the Caspian depression and Aral Sea basin are part of the same structure but with an internal watershed.

The local climate is dry. Annual rainfall amounts to only around 100 mm, making the region of the basin a semi-desert. Winters are cold, summers hot, and rain mainly comes from showers in between these seasons. There are only two major rivers in the region: the Persian names are Amu Darya and the Syr Darya. (As you may guess; ‘Darya’ means river; the names are sometimes written as one word.) The names are recent: the Amu Dary was originally known as the Oxus and the Syr Darya as the Jaxartes. These are the two largest rivers in western Asia. The Amu Darya comes from the Pamir mountains, with two sources on the border between Afghanistan and Tajikistan. It flows over 2,500 km in length and is the longest river here. The Syr Darya comes from the Tian Shan mountains, with a source in Kyrgyzstan. Alexander the Great complained about this uncrossable river: it became the border of his conquests. The rivers benefit from the high snow-rich mountains, but the water flow is dependent on the amount of snow and varies from year to year.

Both rivers flow into the Turan lowland and into Aral Sea. No river flows out from this basin: it is the rivers’ final destination. This imbalance is the main reason for the existence of the Aral Sea.

A Sea Oasis

The rivers feed the same large body of water at their terminus, though with different entry points. The original Aral Sea is (or was, around 1960) a brackish-water lake covering an area of 67,499 km² with a water volume of 985 km³. 75% of this water came from the rivers: they brought around 56 km³ of water per year. The spring and autumn rains into the lake (130 mm per year) added 9 km³. Evaporation of 66 km³ balanced the water level. The high evaporation (in summer) and lack of outflow made the water brackish; the salt levels are about a third of that of sea water. The sea is not particularly deep: typically 10-20 meters only. The name ‘Aral’ refers to the multitude of islands which stuck out from the shallow sea: ‘Aral’ means island.

The Aral Sea contains four separate basins. The main area of the Sea forms a shallow basin. On the western and northern edge are the deeper west basin, a small northwestern Tsebasch basin and the northern basin. The western basin is 60 meters deep. As the region is only around 50 meters above sea level, this puts the bottom here below sea level. The Amu Darya enters from the south into the main basin, and the Syr Darya flows into the northern basin from the east.

The semi-desert around the Aral Sea is inhospitable and sparsely populated. The novelist Andrei Platonov describes it as ‘a land that is pale and salty, as if its tears have dried but its grief has not run its course’; he also calls it ‘the hell of the whole earth’. Obviously, he did not like it! This is the Kara-Kum, the red desert. But the Aral Sea was different. It teemed with life. There was a vibrant fishing industry in towns such as Moynaq, on the southern shore, where some 30,000 people lived, and Aralsk on the north side of the sea. Fishermen would go out for days to collect their catch: sturgeons, trout and beams, among some 20 different species. A 6^th of the fish eaten in the Soviet Union came from here. In the 19^th century, the Russian navy had a base on the Aral Sea, although they found it difficult to get their ships on location. Maybe that is what really differentiates a sea from a lake: a navy.

Where the rivers flowed into the Aral Sea, fertile deltas build up. These acted as oases in the semi-desert, with lush growth and an abundance of wildlife. Caspian tigers occurred here, living off the wild boar and bactrian deer. This subspecies of the Siberian tiger lived along rivers and lakes, and ranged from China to Turkey, the widest distribution of any of the tiger subspecies. One specimen, not fully grown, was shot in 1949 near the Aral Sea. It was probably among the last sightings of tigers there. Its stuffed remains were for a while on display in a museum in the city of Nukus. Tigers remained present further south along the Amu Darya until the 1960’s. They may even have survived in eastern Turkey until the 1990’s. The Caspian tiger was declared extinct in 2003.

The Aral Sea was an oasis in the Steppe. But it was a fragile one. And the Kara-Kum was waiting.

The vanishing sea

The Soviet Union had other priorities than the environment. This started early: already in the 1930’s, Vozrozhdenya island (the largest island in the Aral Sea) was used for secret bioweapon development. This started with open-air experiments, before building a contained facility. The idea was that if containment was broken, only the island would be affected.

Then came the white gold of cotton. The Soviet Union decided that cotton was the future. For a while, Uzbekistan was to produce more cotton than any other country in the world. But cotton is a thirsty plant and the Steppe is dry, not well suited to such a crop. In the 1950’s, plans were made to use water from the two major rivers for this purpose. A canal was build to divert the water of the Amu Darya, with predictable (and predicted) consequences: after 1960, water flow in the Amu Darya suffered. Water from the Syr Darya also ended up in large irrigation lakes. Inflow into the Aral Sea decreased, but evaporation continued and now the water level the Aral Sea was beginning to drop. Because the sea was not deep, small changes in water level quickly lead to large changes in area. The port cities saw the sea withdraw from them.

This had been expected: cotton was seen as more important than fish. But to the locals, it was bad news. Already in the 1950’s, it was known that the Aral Sea would change and at the least become more saline. New fish species were introduced in the mid 1950’s – whether to safeguard against the coming changes or just to diversify the fishery is not clear to me. The introductions even included baltic herring, but that was a change too many. The herring was too prolific, eating all the plankton and then dying from lack of food. Other fish species, such as the black carp, were more successful and in the 1960’s displaced most of the native fauna. Eventually, this preparation would be in vain as the sea’s decline continued unabated.

At first, the falling water level was managed by mooring the ships further from the original shoreline. There were still fish, and catches were fine. The harbour at Aralsk fell dry but the jetty could be made longer. This all changed in 1976. In the mid 1970’s, fresh and brackish water species disappeared. A few years earlier the water had become too saline for the young fish, and now the lack of reproduction reached the mature fish population. A local fisherman recalled how the catch suddenly collapsed in 1976 and 1977. And by 1979, a new problem arose. The fish was taken by transport ship from Aralsk to the factory in Moynaq but the sea had become too shallow and the ships could no longer get across. Five years later, the level in the Aral Sea had dropped 12 meters. Large areas were becoming dry and the fishing industry was dead. By the end of the 1990’s, there were no fish of any kind left in the Large Aral Sea.

The falling levels had another unwanted consequence. People were getting too close to Vozrozhdenya island. In August 1971, a marine biologist from Aralsk was studying the plankton. She suddenly became ill with high fever and a rash, and later bleeding sores. Her young brother too fell ill and so did his school teacher. The marine biologist died. Only now was the disease diagnosed as smallpox – a variant that had been tested at Vozrozhdenya island. The entire town of 40,000 people was cordoned off and everyone was vaccinated. This instant response worked: only a few more people contracted the disease, though two more died of it.

The water levels kept falling and more and more of the sea fell dry. Only now did the Soviet Union report on the situation. Earlier it had been kept secret, in a country were internal disasters, such as airline crashes, were never reported. When perestroika came in the mid-1980’s, this changed. But the new openness did not change the lack of water: in some years the Amu Darya dried up before reaching the Aral Sea. In 1987, the northern part became separated from the main basin. By 1989, the Aral Sea had halved in size, mainly by contraction of the southern and eastern shore. By now the sea had fallen so low that the islands became peninsulas. By 2010, the water level had dropped 30 meters; the Aral Sea had become divided into several separate lakes. The main Aral Sea became reduced to a small central area which in 2014 dried up completely. Only the deeper basins along the western and northern edge still held water.

The decline is nicely illustrated in this NASA article. In wet years the main basin contains shallow lakes. In dry years, it dries up completely. The rest of the sea consists of several isolated bodies of water, one for each of the other three basins. The western basin has become saltier than the sea and little life is left in it.

The climate in the area changed, not surprisingly. The summer is now hotter but winter frost lasts longer and the growing season has shortened. The dry sea bed has left salt deposits, which are blown by the wind. This is badly affecting the health of the local people, not helped by the pesticides that also ended up in the lake.

Recovery

For a while, a plan was consider to divert water from central Siberia to here, but this was abandoned in the mid 1980’s. In the 1990’s, as the Soviet Union collapsed, new plans were made to save the sea. This coincided with a time of reduced irrigation (due to the economic collapse) which for some years stabilized the water levels – but they started falling again when the economy recovered. In the year 2000, only 2.5 km³ of river water entered the Aral Sea, almost all from the Syr Darya. Although evaporation had also decreased (due to the much smaller surface area of the sea), saving the entire Aral Sea was not possible. Instead, efforts focussed on the northern part, the Small Aral Sea.

In 1992, a dike was build across the outflow channel that connected the higher Small Aral Sea with the remnants of the Large Aral Sea (the main basin). The Syr Darya now fed into the northern part only. This failed dramatically in April 1999 when the Small Aral Sea overtopped the dike during a wind storm, and the dike was swept away. Two people who had been trying to repair the dike were killed in the flood. A larger and better dike was built, called the Kok-Aral dam, which was ready in 2005. It has kept the water level in the Small Aral Sea at 42 meters, which is 10 meters below the 1960 level. In good water years, excess water is fed into the Large Aral Sea.

The Small Aral Sea settled at a salinity similar to that of the old sea. Fishes returned, having apparently survived in the Syr Darya or in some cases, were re-introduced. The Aral salmon was lost for good, sadly. Total catches are now 5-10 times lower than those of the old Ara Sea, but it provides a living. Kazakhstan has considered building a second dam within the Small Aral Sea, to raise the water level further in the bay at Aralsk and allow use of its old harbour.

The highly salty western Aral Sea (the Shevchenko Gulf) is now used for brine shrimps. This species was introduced because it could deal with the very high salt content, and brine shrimp eggs are used as fry food in fish farms. The processing company remains located in Moynaq, 200 km away, which means long treks in four wheel drives across the salt plains. The fish processing plant here now imports its fish from Russia in a dubious feat of economic planning. (Aralsk now has its own processing plant.) There is a little tourism. Moynaq is known for its ship cemetery where some of the rusted hulks are left to decay: many of the photographs of dying ships are taken here. But the ships did not get stranded here: they died elsewhere and were taken back.

There are no plans for full restoration of the Aral Sea. The recovery will instead remain focussed on the Small Aral Sea which falls fully within Kazahkstan.

The Large Aral Sea and its surroundings have become the newest desert on Earth. It has become known as the Aral-Kum. Instead of recreating the Aral Sea, Uzbekistan has created a development plan for the region, aided by the World Bank. Food production remains its priority, in conflict with the needs of the Aral Sea. An attempt is made to plant saxaul bushed in the dry sea bed, to stabilize the soil, but as yet this is limited to a 500-hectare demonstration site. And since 2022 Afghanistan is building a canal to divert 20% of the Amu Darya, making it even less likely that the Large Aral Sea will ever return.

And there may be problems coming for the Small Aral Sea as well. Flow in the Syr Darya is decreasing, as more and more of its water is used along the course of the river. There is no guarantee that even the Syr Darya will continue to reach the Sea.

Some life has returned to Aralsk on the Small Aral Sea, but elsewhere the signs are not good. The Sea will not dry out completely: at the very least the rains will still fall. But this will only be a hyper-saline remnant.

The flat, dry sea bottom is covered in sea shells, with sparse bushes in the dessicated landscape. Salt is everywhere. Even the camels die from eating the salt-covered vegetation. Young people show stunted growth, caused by the pesticide-laden sand storms. Global warming is now adding to the pressures in the region. Sand dunes are approaching from the south and are covering the old, abandoned towns.

Condemned to repeat

Those who forget the past are condemned to repeat it. It turned out that the Aral Sea had always been an unstable entity. Its water armageddon has happened before.

The water flow in the rivers is very sensitive to climate – even when both rivers feed into the Aral Sea, the amount of water is not guaranteed. Fluctuations in water level of the Aral Sea by a few meters were not uncommon, and much larger variations have occurred. The decades before 1960 were, in hindsight, more stable than usual. When the Aral Sea dried up, old river beds of the Syr Darya appeared on the sea floor, a sign that the water once had been much lower than in 1960. This has in fact happened more than once, even in the fairly recent past.

In the northern part of the Large Aral Sea, ruins of old settlements appeared, some 20 meters below 1960 water levels. There are three, called the Kerderi cluster, dated to around the 14^th or 15^th century, and having lasted around 200 years. Although there is little left, the remains include two mausolea with ceramics and mosaics: this was a significant settlement, perhaps involved with the silk road. A document from around this time (1417) comments that the Amu Darya flowed into the Caspian Sea and that the Aral Sea had ceased to exist. That overstated things: the presence of settlements suggests water remained, but at a much reduced level. The Amu Darya was said to have returned to the Aral Sea around 1573. By 1700 the Aral Sea is depicted on maps at its current (i.e. 1960) size. The low level would have lasted from around 1200 to 1600.

And this had happened before. Before the 6^th century AD, the Amu Darya also ran towards the Caspian Sea and the Aral Sea was much lower. This lasted perhaps 500 years.

The cause was in the high mountains. Both rivers carry sediment from the mountains, and this becomes deposited on the flat plains of the Aral Sea Basin. It silts up the river bed, forcing the river to change course. Especially the Amu Darya is affected by this. Just a small change in its pathway can cause it to miss the Aral Sea entirely and instead flow into the Caspian Sea.

The Aral Sea was always precarious: its level varied dramatically with the course of the Amu Darya. The Syr Darya was more reliable, as shown by the fact that it produced river beds at these times while the Amu Darya did not.

In fact, before around 2000 BC the Amu Darya may not have reached the Aral Sea at all. Without the Amy Darya, the Aral Sea would have been much smaller or dry. This had lasted for many thousands of years. There was only one reliable river (Syr Darya) flowing into the Aral Sea. The Amu Darya was always a much more fickle entity. And the Syr Darya only came some time after the ice age: before that, it went into a different direction.

The ‘modern’ Aral Sea seems to have been a relative recent development. The Aral Sea was perhaps the world’s youngest sea, dating only to the middle holocene.

Before time

The Caspian Sea and the Aral Sea are separated by a watershed which is only a few meters higher than the 1960 water level. Water levels in the Caspian Sea were particularly high at the end of the ice age, high enough to overflow the watershed. At this time a huge body of water connected the two seas. This overflow may be the reason that the fauna of the two seas were quite similar.

And this had not been not an isolated occurrence. During the late pliocene (from some three million years ago), the Aral Sea was mostly an extension to the Caspian Sea although it did dry out at several times when the connection was lost. The ice age was dry, until the melt temporarily re-established the large sea. Once that ended, the Aral Sea had to wait for the rivers to establish themselves.

The Tethistan

We mentioned how the Caspian depression and the Aral Sea Basin form a huge low-lying area. But why is this basin here? To the south are the enormous mountain ranges, in places 7 km tall. To the north is the Siberian plateau, typically 500 meters high (and covered by the Siberian traps, but that is a different story). In between is this low-lying land, close to sea level at Aral and as low as 200 meters below sea level in the Caspian Sea.

Looking at a map of the continent, a series of water-filled depressions show, from the Black Sea to Lake Balkash. It is much shorter and not quite as recognizable as the line of mountains from Spain to Thailand, but it shadows this line. If these mountains are the scar of the Tethys ocean, the line of lakes and seas are the accompanying itch. We are in the shadow of the Tethys.

Once, the Tethys divided the world between north and south. It was home to a progression of continental cast-offs from Gondwana in the south which crossed the sea towards the north. When they arrived, each would dock at far too high a speed (have you ever tried to stop a continent moving at 10cm/year?) and would raise a crumple zone. Hence the mountains – each of the chains which make the line come from a separate collision, all part of the complex closing of the Tethys ocean. The Tian Shan formed from an old suture (from the merging of the Tarim plate of China with Siberia, 300 million years ago), re-activated by stress from India, 40 million years ago. Mountains further west come from other additions to Eurasia. Each of these contributed to the slow demise of the Tethys ocean until it finally ceased to exist 5 million years ago.

In the process, the various collisions divided the Tethys ocean. One part is called the Paratethys: it sat north of Turkey around 30 million years ago. The past existence of the Paratethys was recognized already in the 19^th century, as the remains of an ancient Mediterranean stretching from Crimea to the Aral Sea. Nowadays we make it even larger. The Paratethys became isolated from the main Tethys ocean some 15 million years ago and slowly disappeared.

The disappearance left the deep salt deposits of eastern Europe, as far west as the appropriately named Salzburg. The lively salt trade of medieval Europe is based on the inheritance from this dying ocean. But as for its water, the only seaworthy survivors were the Black Sea, the Caspian Sea and the Aral Sea.

Don’t expect oceanic crust here: this was mostly a shallow ocean from submerged continental margins. Only the Black Sea and the southern Caspian Sea contain some true oceanic crust – among the last remnants of the original Tethys Ocean. Elsewhere are a number of separate continental blocks which underly the basins, each with their own origin. What they have in common is the Paratethys.

After the isolation, the Paratethys ocean became brackish. Sea life adapted to this. These adaptations still survive in the Caspian Sea. During the pliocene the Aral Sea became a gulf attached to Caspian Sea, which at times would completely dry out. In the early holocene, its connection to the Caspian was severed and it became reliant on rivers for its waters. But its fauna still dated to that time when it was a Caspian Gulf, and from there to the era of the Paratethys.

Tethys, daughter of Gaia and wife of Oceanus, was the goddess mother of the water nymphs of the lakes and the seas. Asia too was one of her daughters. The Aral Sea, this temperamental child-sea, is her offspring.

The Tethys ocean has left us much of the geology of the modern world. Its rocks and mountains are everywhere. But here is another memory. The Aral Sea is part of a line in the sand saying ‘I was here’. It is tectonic graffiti. Long might it have lasted.

Albert, September 2024

A few references

The Aral Sea Environment, 2010, Editors: Andrey Kostianoy and Aleksey N. Kosarev. Published by Springer

Paleogeographical History of the Aral Sea. Alexander Svitoch. In: The Aral Sea Environment.

The Aral Sea: A Story of Devastation and Partial Recovery of a Large Lake. Philip Micklin et al., 2020 https://link.springer.com/chapter/10.1007/978-3-030-42254-7_4

Past, Present and Future of the Aral Sea -A Review of its Fauna and Flora before and during the Regression Crisis. Igor Plotnikov et al, 2023, Zoological Studies 62, e19

The last Caspian Tiger. Robert Chandler, 2005. https://journals.sagepub.com/doi/pdf/10.1080/03064220512331339571

https://daviscenter.fas.harvard.edu/insights/aralsk-kazakh-town-lived-through-smallpox-epidemic