Climate change is fast shrinking the world’s largest inland sea

Formerly a paradise for flamingos, sturgeons and thousands of seals, rapid reception waters transform the north coast of the Caspian Sea into sterile sections of dry sand. In some places, the sea fell more than 50 km. Wetlands become deserts, fishing ports are left high and dry, and oil companies are to flirt with longer and longer canals to reach their offshore facilities.

Climate change leads to this spectacular drop in the largest sea without coast in the world. Found at the border between Europe and Central Asia, the Caspian Sea is surrounded by Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan, and supports about 15 million people.

The Caspian is a hub for fishing, shipping and production of oil and gas, and has an increasing geopolitical importance because it is when the interests of world superpowers meet. As a sea of ​​the sea, governments are faced with the essential challenge of maintaining industries and livelihoods, while protecting the unique ecosystems that support them.

I have been visiting the Caspian for over 20 years, working with local researchers to study the Caspian and endangered Caspian seal, and support its conservation. In the 2000s, the angle of the extreme northeast of the sea was a mosaic of reeds, mud deflats and shallow canals that grouped together, providing habitats for enriching fish, migratory birds and tens of thousands of seals that gathered for moult in spring.

Now, these distant wild places that we have visited to catch seals for satellite monitoring studies are dry land, in transition to the desert while the sea is withdrawn, and the same story is played for other wetlands around the sea. This experience is parallel to that of the coastal communities, which, year by year, see the water moving away from their cities, fishing and ports, leaving them. Infrastructure blocked on newly dry land and people who are afraid for the future.

A retired sea

The Caspian sea level has always fluctuated, but the extent of the recent change is unprecedented. Since the beginning of the current century, water levels have decreased by around 6 cm per year, with drops up to 30 cm per year since 2020. In July 2025, Russian scientists announced that the sea had fallen below the previous minimum level recorded at the time of instrumental measures.

During the 20th century, variations were due to a combination of natural factors and humans who divert water to use for agriculture and industry, but now global warming is the main engine of the decline. It may seem inconceivable that a body of water as large as the Caspian can be in danger, but in the warmer climate, the water level entering the sea from rivers and reduced precipitation, and is now exceeded by increased evaporation of the sea surface.

Even if global warming is limited to the objective of the 2 ° C Paris agreement, the water levels should fall up to 10 meters from the coast of 2010. With the current global trajectory of greenhouse gas emissions, the decline could reach 18 meters, which is roughly up to a six -story building.

Because the Northern Caspian is shallow – just about five meters deep – decreases in depth in depth with enormous area loss. In recent research, his colleagues and I have shown that even an optimistic decline of ten meters would reveal 112,000 square kilometers of seabed – an area larger than Iceland.

What is at stake

The ecological consequences would be dramatic. Four types of ten -ten ecosystems specific to the Caspian Sea would disappear completely. The endangered Caspian seal could lose up to 81% of its current reproduction habitat, and the Caspian sturgeon would lose access to critical Frai habitat.

As in the Aral Sea disaster, where another massive lake in Central Asia has almost completely disappeared, the toxic dust of the seabed exposed would be released, with serious health risks.

Millions of people are at risk of travel as the sea moves away or faces very degraded living conditions. The only link in the sea with the world shipping network is through the Delta de la Rivière Volga (which flows into the Caspian), then via a channel upstream to the Don river for connections with the Black Sea, the Mediterranean and other river systems. But the Volga is already in difficulty with a reduced depth of water.

Ports like Aktau in Kazakhstan and Baku in Azerbaijan need dredging just to continue working. Likewise, oil and gas companies must flirt with long canals to their offshore facilities in the north of the Caspian.

Already, human interest protection costs are in billions of dollars and are only to grow. The Caspian is at the heart of the “corridor in the middle”, a commercial route connecting China to Europe. As the water levels drop, shipping charges must be reduced, cost increases and establishments and infrastructure may be blocked by tens, even hundreds of kilometers from the sea.

A race against time

The countries around the Caspian must adapt, move ports and flirt with new shipping routes. But these measures risk conflict with conservation objectives.

For example, it is planned to flirt with a new major shipping channel through the “Ural saddle” of the North Caspian. But this is an important area for breeding, migration and feeding of seals, and will be a vital area for the adaptation of ecosystems as the sea moves.

Since the change rate is so rapid, traditional areas protected by fixed limits may become obsolete. What is necessary is an integrated and prospective approach to planning throughout the region. If regional ecosystems will have to adapt to climate change are mapped and protected now, political planners and decision -makers will be able to guarantee that future infrastructure projects avoid or minimize other damage.

To do this, the Caspian countries will have to invest in the expertise in monitoring and planning biodiversity, while coordinating action in five different countries with different priorities.

Caspian countries already recognize existential risks and have started to train intergovernmental agreements to deal with the crisis. But the drop rate can exceed the pace of political cooperation.

The ecological, climatic and geopolitical importance of the Caspian Sea means that its fate ultimately counts far beyond its retreat. It provides a key case study on the way in which climate change transforms the main interior bodies of water around the world, from Lake Titicaca to Lake Chad. The question is whether governments can act quickly enough to protect both people and the nature of this rapidly evolving sea.

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