The world’s largest lake is disappearing rapidly

After only a decade, the coastal road that Azamat Sarsenbayev often chose to jump into the blue Caspian Sea left only empty land full of rocks stretching to the horizon. The water receded far and fast from the city of Aktau in Kazakhstan, where the environmental activist had lived all his life. More than 1,600 km south, near the city of Rasht, Khashayar Javanmardi was also alarmed because the sea here was heavily polluted.

The Caspian Sea is the largest inland sea on the planet and the largest lake in the world. This body of water has an area equivalent to the US state of Montana. Its coastline extends over 6,437 km and is shared by five countries: Kazakhstan, Iran, Azerbaijan Russia and Turkmenistan. These countries depend not only on the Caspian Sea for fishing, farming, tourism and drinking water, but also for its oil and gas reserves. The Caspian Sea also helps regulate the climate of the arid region, providing rainfall and moisture to Central Asia.

Dam construction, resource exploitation, pollution and human-caused climate change are leading to a decline in lake water, and some experts fear the Caspian Sea will be pushed to the point of no recovery. . While climate change increases global sea levels, the situation is different for inland seas like the Caspian. They depend on a delicate balance between water flowing in from rivers and rainfall and water lost through evaporation. That balance is changing as the world warms, causing many lakes to shrink.

For example, the nearby Arabian Sea, which crosses Kazakhstan and Uzbekistan, was once one of the world’s largest lakes but is disappearing under destruction from human activity combined with escalating climate change. Over thousands of years, the level of the Caspian Sea repeatedly rose and fell as temperatures fluctuated and ice shelves expanded and contracted. However, over the past few decades, the decline in water levels has been accelerating.

Human activity plays an important role when countries build reservoirs and dams. Although 130 rivers flow into the Caspian, about 80% of the water comes from the Volga, Europe’s longest river winding through central and southern Russia. Russia has built 40 dams and is developing 18 more, according to Vali Kaleji, an expert in Central Asia and Caucasus studies at Tehran University, reducing the flow of water into the Caspian Sea.

However, climate change is also playing an increasingly important role, increasing evaporation rates and making rainfall more volatile. The water level of the Caspian Sea has been falling since the mid-1990s, but the rate of decline has accelerated since 2005, dropping by 1.5 meters, according to Matthias Prange, an Earth system modeling expert at the University of Bremen in Germany.

As the world warms further, Caspian Sea levels will drop significantly. Prange’s research predicts a decline of 8 to 18 meters by the end of the century, depending on how quickly the world cuts fossil fuel pollution. Another study indicates a decline of up to 30 m could occur by 2100. Even under optimistic conditions, the shallower northern part of the Caspian Sea, mainly surrounding Kazakhstan, would disappear completely, according to Joy Singarayer, professor of paleometeorology at the University of Reading.

For the countries around the Caspian Sea, this is a crisis. There will be fewer places to catch fish, tourism will decline, and the maritime industry will be affected because ships will have difficulty docking in shallow water port cities like Aktau.

The current situation is dire for the unique wildlife of the Caspian Sea. It is home to hundreds of species, including endangered wild sturgeon, the source of 90% of the world’s sturgeon eggs. The Caspian Sea has been surrounded by land for at least 2 million years, and its isolation has led to the emergence of strange species. But lowering water levels deplete oxygen levels in deep water, potentially wiping out species that have survived millions of years of evolution, especially for Caspian seals, an endangered marine mammal species that cannot be found. seen elsewhere on Earth. Their nursery grounds in the shallow waters of the northeastern Caspian Sea are disappearing as the species struggles to cope with pollution and overfishing.

In Kazakhstan, Sarsenbayev is seeking to draw attention to the state of the Caspian Sea. If the climate crisis and over-exploitation continue, he fears the Caspian Sea could face a similar fate to the Aral Sea.