Caspian Sea decline threatens wildlife, human health, and industry

Urgent action is needed to protect endangered species, human health, and industry from the impacts of the Caspian Sea’s decline.

In a new study, scientists from the University of Leeds have mapped the potential risks posed by the shrinking Caspian Sea to the region’s biodiversity and infrastructure.

Water decline in the Caspian Sea

Water levels in the Caspian Sea – the world’s largest landlocked water body – are shrinking as hotter temperatures cause more water to evaporate than flows in.

Even if global warming is limited to below 2°C, the sea level is expected to decline by 5 to 10 meters. If temperatures rise further, levels could drop by as much as 21 meters (more than 68 feet) by 2100.

The findings show that an area of 112,000 km² – larger than Iceland – could dry up, even in an optimistic warming scenario with a 10-meter decline.

Because many of the most ecologically and economically important areas lie in shallow water, the consequences could be severe for biodiversity and the sustainability of human life in the region.

Risks of low water levels

The sea is home to the endangered Caspian seal, six species of sturgeon, and hundreds of fish and invertebrate species that cannot be found anywhere else.

According to the researchers, declining water levels will reduce breeding habitat for Caspian seals, block sturgeon access to spawning rivers, and destroy coastal lagoons and reed beds vital for spawning fish and migrating birds.

In addition, more than 15 million people live along 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 climate in Central Asia.

Some places will be stranded

In the northern Caspian, the study’s findings show that some settlements, ports, and industrial facilities could end up stranded tens or even hundreds of kilometers from the new shoreline.

The exposed seabed is likely to release dust containing industrial contaminants and salt, posing serious threats to human health – as happened during the drying of the Aral Sea.

The researchers argue that 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.

Proactive measures are needed

Simon Goodman, a researcher in the School of Biology at the University of Leeds, led the study.

“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,” said Goodman.

“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 seal habitat

Currently, the Caspian Sea extends approximately 1,150 by 450 kilometers, with a total area of 387,000 square kilometers.

With a 10-meter decline, four out of ten ecosystem types unique to the Caspian Sea are expected to disappear entirely, and the coverage of existing marine protected areas could shrink by up to 94 percent.

Caspian seals give birth to white-coated pups between mid-January and early March on ice in the northern Caspian Sea. However, the research shows that a 5-meter decline could reduce this habitat by up to 81%, putting extreme pressure on their already diminished population.

The Caspian seal was listed as endangered by the International Union for Conservation of Nature (IUCN) in 2008 and appears 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.

Vanishing habitats for birds and fish

Sturgeons are an ancient family of large fish, and critically endangered due to overfishing for their meat and 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 accessing their few remaining spawning sites in rivers that flow into the sea.

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.

Awareness of Caspian Sea decline

Although work has been done to protect areas important for biodiversity, the paper predicts that overall coverage of existing Caspian marine protected areas will disappear almost entirely for all countries except Kazakhstan, which would retain about 5% of current coverage.

Rebecca Court, a PhD researcher in the School of Earth and Environment at Leeds, worked on the research as part of her master’s degree in the School of Biology.

“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, pipelines, and peril

The findings also predict troubling consequences for industry, with key ports in all bordering countries expected to be affected. Baku (Azerbaijan), Anzali (Iran), and Aktau (Kazakhstan) may experience shoreline retreats of 1 km or more.

Turkmenbashi (Turkmenistan) and Lagan (Russia – a planned future site) could see shoreline shifts of 16 km and 115 km, respectively, according to the study.

The Volga is the only river connecting the Caspian Sea to the global maritime network, and this vital trade route could be severely compromised by a decline of just five meters.

The Kashagan and Filanovsky oil fields in the northern Caspian are among the region’s most important hydrocarbon production sites.

Currently, production takes place at offshore installations using ship-based logistics, but these operations will become landlocked if Caspian Sea levels fall by 5 to 15 meters.

Communities in the crosshairs

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

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.

The 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.

Finally, the energy resources of the Caspian Sea make it geopolitically significant. As a result, social, economic, and environmental instability caused by climate change could have worldwide repercussions.

Risks posed by climate change

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, supporting coastal communities to diversify economically, enabling flexible protected areas with fluid boundaries, and taking preemptive steps to avoid conflicts between conservation and infrastructure adaptation.

The team also stresses the urgency of reducing greenhouse gas emissions globally and warns in order to mitigate these projected impacts, coordinated regional planning and global collaboration are essential.

“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,” concluded Elchin Mamedov from the Azerbaijan Ministry of
Ecology and National Resources.

The study is published in the journal Nature Communication: Earth and Environment.

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