Caspian Sea tragedy: The world's largest lake is drying up!

​(HIGH) Just a decade ago, when Azamat Sarsenbayev jumped into the Caspian Sea - the largest lake in the world - to swim, he could still feel the brackishness of the water and its blue color. But now, this giant lake is just a barren, rocky land stretching towards the horizon.

The water has receded rapidly from the city of Aktau in Kazakhstan, a city on the Caspian Sea where the eco-activist has lived all his life. "It's hard to see," he told CNN.

More than 1,000 miles to the south, near the Iranian city of Rasht, Khashayar Javanmardi is also worried . The Caspian Sea in this area is heavily polluted.

"I can't swim anymore. the water has changed," the photographer, who has traveled across the southern coast of the Caspian Sea, documenting its deterioration, told CNN.

Aerial images of the Caspian Sea show the world's largest lake is drying up.

The lake is dying

Both men feel a strong connection to the water they grew up with. Both fear for its future.

The Caspian Sea is the largest inland sea on the planet and the largest lake in the world . It contains a huge body of water roughly the size of the US state of Montana. Its arc of 'shorelines' stretches over 4,000 miles and is shared by five countries: Kazakhstan, Iran, Azerbaijan, Russia and Turkmenistan.

These countries rely on it for fishing, farming, tourism and drinking water, as well as the oil and gas reserves beneath it. The Caspian Sea also helps moderate the climate of this arid region, providing rainfall and moisture to Central Asia. But it is in trouble.

Damming, overfishing, pollution and, increasingly, the man-made climate crisis are driving its decline. Some experts fear the Caspian Sea is being pushed past the point of no return.

While climate change is causing global sea levels to rise, the story is different for inland (landlocked) lakes and seas like the Caspian Sea. They rely on a delicate balance between water flowing in from rivers and rainfall and water escaping through evaporation. This balance is changing as the world warms, causing many inland lakes like the Caspian to shrink.

People don't have to look far to see what the future might hold. The nearby Aral Sea, located between Kazakhstan and Uzbekistan, was once one of the world's largest lakes but has all but disappeared, devastated by a combination of human activity and the escalating climate crisis.

For thousands of years, the Caspian Sea has fluctuated between high and low water levels as temperatures fluctuated and ice sheets advanced and retreated. But in the past few decades, the decline has accelerated.

Human activity plays a major role, as countries build reservoirs and dams. The Caspian Sea is fed by 130 rivers, although about 80% of its water comes from just one: the Volga, Europe's longest river, which winds through central and southern Russia.

The port city of Aktau, Kazakhstan on the Caspian Sea.

Russia has built 40 dams, with another 18 under construction, according to Vali Kaleji, an expert on Central Asian and Caucasus studies at Tehran University in Iran. This reduces the flow of water into the Caspian Sea.

But climate change is playing an increasingly important role, increasing evaporation rates and causing more erratic rainfall.

The Caspian Sea's water level has been falling since the mid-1990s, but has accelerated rapidly since 2005, said Matthias Prange, an Earth system modeler at the University of Bremen in Germany.

As the world warms further, water levels will 'decrease dramatically,' Prange told CNN. His research predicts water levels will fall between 8 and 18 meters by the end of the century, depending on how quickly the world cuts fossil fuel pollution.

Even under more optimistic global warming scenarios, the shallower northern part of the Caspian Sea, mainly around Kazakhstan, would disappear completely, said Joy Singarayer, professor of climatology at the University of Reading and co-author of the study.

For the Caspian Sea countries, this is a crisis. Fishing grounds will shrink, tourism will decline and shipping will suffer as ships struggle to dock at shallow port cities like Aktau, said Kaleji of Tehran University.

There will also be geopolitical consequences. Five nations competing for dwindling resources could culminate in 'a race to exploit more water ,' Singarayer notes. It could also spark new conflicts over oil and gas reserves, if shifting coastlines spur nations to make new claims.

Caspian Sea seals on the coast of Russia. The species is in danger of extinction as the water levels of the Caspian Sea continue to decline.

Crisis awaits

The situation has become dire for the unique wildlife of the Caspian Sea , home to hundreds of species, including the endangered wild sturgeon, which supplies 90% of the world's caviar.

The sea has been closed off for at least 2 million years, its extreme isolation leading to " the appearance of strange creatures like very strange clams" - according to Wesslingh.

It's also a crisis for the Caspian seal, an endangered marine mammal found nowhere else on Earth. Their breeding grounds in the shallower northeastern Caspian Sea are changing and disappearing, as the animal also struggles with pollution and overfishing.

Aerial surveys have shown a major decline in seal numbers, said Assel Baimukanova, a researcher at the Institute of Hydrobiology and Ecology in Kazakhstan.

Many areas of the Caspian Sea are dry.

There are few easy solutions to this crisis. The Caspian Sea is located in a region that has experienced much political instability and is shared by five countries, each of which will experience the decline in its water levels in different ways.

No single country is responsible, but if they do not act collectively, the Aral Sea disaster could repeat itself, Kaleji stressed, adding that there is no guarantee that the Caspian Sea "will return to its natural and normal cycle."

Growing concerns about the fate of the Caspian Sea come at a time when the region is under closer scrutiny.

Next month, global leaders will gather in Azerbaijan's coastal capital Baku for COP29, the United Nations' annual climate summit, where they will discuss action on climate change in the shadow of oil rigs dotted across this Caspian Sea region.

In August, Azerbaijani President Ilham Aliyev said the decline of the Caspian Sea was 'catastrophic' and was becoming an ecological disaster, but at the same time, the country also plans to expand its own fossil fuel production, which is driving the decline in the Caspian Sea's water level.

Back in Kazakhstan, Sarsenbayev is trying to draw attention to the plight of the Caspian through beautiful, sweeping footage he posts on Instagram.

If the climate crisis and overexploitation of water continue, he fears 'the Caspian Sea could face the fate of the Aral Sea'.

In Iran, Javanmardi continued to photograph the Caspian coast, documenting the polluted waters, shrinking shorelines and dry seabeds, as well as revealing the beauty that still exists and the human connection to the sea. He wanted to awaken people to what is disappearing.

'This is the largest lake in the world, everyone should take it seriously,' he said.