The Caspian Sea Is Drying Up: Endangered Seals, Vanishing Shorelines, and a Climate Crisis

As climate change drives down the water levels of the Caspian Sea, a staggering transformation is unfolding – ecosystems are vanishing, endangered species face extinction, and millions of people risk losing their livelihoods.

From disappearing coastlines to crumbling industry and threatened biodiversity, the region’s future hangs in the balance unless urgent and coordinated action is taken across borders.

Caspian Sea Faces Alarming Water Loss

Water levels in the Caspian Sea, the largest landlocked body of water in the world, are steadily falling as rising temperatures cause more evaporation than inflow. Even if global warming is kept below 2°C, scientists estimate the sea could drop by 5 to 10 meters. If temperatures rise further, the decline could reach up to 21 meters by the end of the century.

In a study published today (April 10) in Communications Earth & Environment, researchers from the University of Leeds mapped out the potential impacts of this dramatic drop on the region’s ecosystems and infrastructure.

Biodiversity and Human Impact Zones at Risk

Their analysis shows that up to 112,000 square kilometers, an area larger than Iceland, could dry out, even under the more optimistic scenario of a 10-meter decline. Because many of the Caspian’s most critical ecological and economic zones lie in shallow waters, the consequences for biodiversity and human livelihoods could be severe.

The Caspian Sea is home to the endangered Caspian seal and six species of sturgeon, as well as hundreds of species of fish and invertebrates found nowhere else. According to the research, the declining water levels will leave Caspian seals with significantly reduced breeding habitat, restrict access to spawning rivers for sturgeons, and lead to the loss of coastal lagoons and reed beds important for the spawning of other fish species and migrating birds.

Vital Resource for Millions

More than 15 million people live around the Caspian coast, in Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan. The bordering nations rely on the water body for fishing, shipping, and trade, and the sea is important for regulating the climate in Central Asia.

In the northern Caspian, the findings show that some settlements, ports, and industrial facilities could end up being stranded tens or even hundreds of kilometers from new shorelines. The exposed dry seabed is likely to release dust containing industrial contaminants and salt, posing serious threats to human health, as previously occurred with the drying of the Aral Sea.

Rethinking Conservation in a Changing Landscape

The researchers say policymakers and conservationists need to take a dynamic approach to biodiversity protection, rather than relying on traditional protected areas with fixed boundaries, since these may quickly become obsolete due to the rapidly changing water levels.

Dr. Simon Goodman from the School of Biology at the University of Leeds, who supervised the research, said: “Some Caspian Sea level decline appears unavoidable, even with action to reduce global greenhouse gas emissions. However, with the anticipated effects unfolding over a few decades, it should be possible to find ways to protect biodiversity while safeguarding human interests and well-being. That might sound like a long timescale, but, given the immense political, legislative, and logistical challenges involved, it is advisable to start action as soon as possible to give the best chance of success.”

Shrinking Sea, Vanishing Habitats

Currently, the Caspian Sea extends approximately 1150 km by 450 km, with a total area of 387,000 km².

With a 10 m decline, four out of 10 ecosystem types unique to the Caspian Sea would be expected to disappear completely, and the coverage of existing marine protected zones (areas earmarked for conservation) would be reduced by up to 94%.

Caspian seals give birth to their white-coated pups between mid-January and early March on ice in the northern Caspian Sea. However, the research shows a 5 m decline could reduce the area of this habitat by up to 81% – putting huge stressors on their already reduced population.

A Species in Crisis

The Caspian seal was listed as Endangered by the International Union for the Conservation of Nature (IUCN) in 2008, and is included in the national Red Books of all five Caspian countries, signifying its recognition as a species at risk of extinction.

The decline will also make all current and historical haul-out sites – areas on land where seals rest – inaccessible. While receding water levels may create some new islands, further research is needed to assess their suitability for seals.

Sturgeons are an ancient family of large fish that are critically endangered due to overfishing for their meat and caviar (fish eggs or roe). The fish usually inhabit shallower parts of the sea in summer and autumn, but these areas are facing a potential reduction of 25% to 45% due to the fall in water levels, which may stop them from accessing their few remaining spawning sites in rivers that flow into the Sea.

Migratory Birds Face Habitat Loss

The Caspian Sea is also a globally important habitat for birds migrating between Europe, Asia, and Africa. Migratory birds rely on coastal lagoons and reed beds for resting, shelter, and food during their migrations, but such habitats are vulnerable to loss as waters recede.

Biodiversity in the Caspian Sea is already threatened by over-fishing, introduction of invasive species, and pollution. Although work has been done to protect areas important for biodiversity, the paper predicts that overall coverage of existing Caspian marine protected areas disappear almost entirely for all countries except Kazakhstan, which would retain about 5% of current coverage.

Rebecca Court, PhD researcher in the School of Earth and Environment at Leeds, worked on the research as part of her Masters degree in the School of Biology. She said: “We hope this research will help to raise awareness of the trajectory and potential impacts of the falling sea level. The mapping should better equip policymakers and conservationists to plan for and address the numerous issues in advance.”

Ports and Trade at Risk

The findings also predict a concerning trajectory for industry, with critical ports in all bordering countries being impacted. Baku (Azerbaijan), Anzali (Iran), and Aktau (Kazakhstan) are expected to experience increases in distance to shore of 1 km or more, while Turkmenbashi (Turkmenistan), and Lagan (Russia; planned future site), could see increases of 16 km and 115 km respectively, according to the paper.

The Volga is the only river connecting the Caspian to the outside maritime world, and this vital trade route could be critically compromised by declines of just 5 m.

Oil Infrastructure in Jeopardy

The Kashagan (Kazakhstan) and Filanovsky (Russia) oil fields in the northern Caspian are two of the region’s most important hydrocarbon production sites. Production currently occurs at offshore installations, with ship-based logistics, but these will become landlocked if Caspian Sea levels decline by 5 to 15 m.

Coastal communities in the north are likely to be hit hard as income from fishing disappears, and harsh climatic conditions make other economic activities like agriculture more difficult, potentially threatening social stability.

Desalination and Regional Climate Impacts

Some cities around the Caspian use desalination (removing salt and minerals from saltwater) for freshwater supplies, and water level declines are already impacting desalination operations at Aktau in Kazakhstan.

Loss of water from the Caspian could also affect the regional climate, leading to reduced rainfall and drier conditions across central Asia with indirect impacts on agriculture.

The energy resources of the Caspian Sea make it important geopolitically, so social, economic, and environmental instability due to climate change could have worldwide repercussions.

A Call for Urgent, Adaptive Action

Going forward, a balance needs to be struck between protecting biodiversity and human prosperity and well-being. The researchers’ recommendations include:

• Investing to enhance regional capacity for biodiversity monitoring, conservation planning, and sustainable development
• Supporting coastal communities to diversify economically and develop resilient infrastructure
• Developing legislation that enables the creation of protected areas with flexible borders
• Taking a pre-emptive planning approach to avoid conflicts between biodiversity protection and efforts to adapt human infrastructure
• Tracking rapidly changing ecosystems and implementing species translocations and ecosystem restoration where needed
• Reducing greenhouse gas emissions at a global scale.

The researchers stress that urgent action is needed, with coordinated regional planning and global collaboration, to mitigate the projected impacts.

Regional Unity Needed to Address Climate Crisis

Dr. Elchin Mamedov from the Ministry of Ecology and Natural Resources, Azerbaijan, said: “This is an important study because it highlights the risks posed by climate change for Caspian region biodiversity and local communities and the need to enhance regional and international cooperation to help manage the impacts.”

Reference: “Rapid decline of Caspian Sea level threatens ecosystem integrity, biodiversity protection, and human infrastructure” by Rebecca Court, Matteo Lattuada, Nataliya Shumeyko, Mirgaliy Baimukanov, Tariyel Eybatov, Altynay Kaidarova, Elchin V. Mamedov, Eldar Rustamov, Aselle Tasmagambetova, Matthias Prange, Thomas Wilke, Christopher Hassall and Simon J. Goodman, 10 April 2025, Communications Earth & Environment.
DOI: 10.1038/s43247-025-02212-5

The international collaboration involved researchers from Technische Universität Braunschweig (Germany), Technische Universität Berlin (Germany), Kaspika Caspian Seals Conservation Agency (Russia), Institute of Hydrobiology & Ecology (Kazakhstan), Museum of Natural History (Azerbaijan), Central Asian Institute of Ecological Research (Kazakhstan), Fisheries and Aquaculture Research Centre (Azerbaijan), Ramsar Regional Initiative of Central Asia (Turkmenistan), University of Bremen (Germany) and Justus Liebig University Giessen (Germany).

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