Rapid declines in the level of the Caspian Sea are disrupting oil shipments, increasing logistics costs and endangering vulnerable marine life, Azerbaijani officials and scientists said.

Deputy Ecology Minister Rauf Hajiyev told Reuters the sea had been getting shallower for decades, but the trend had sharply accelerated. The level has fallen by 0.93 metres in the past five years, 1.5 metres in 10 years and 2.5 metres in 30 years, with the current rate of decline estimated at 20–30 cm annually.

“The retreat of the coastline changes natural conditions, disrupts economic activity and creates new challenges for sustainable development,” said Hajiyev, who represents Azerbaijan in a joint working group with Russia formed in April. Despite strained relations, the two countries plan to approve an online programme in September for monitoring and response.

Russia attributes the decline mainly to climate change, while Azerbaijan also blames Moscow’s construction of dams on the Volga River, which provides 80% of Caspian inflow.

Around 4mn people in Azerbaijan and 15mn across the Caspian littoral depend on the sea. Hajiyev said falling levels were already hindering activity at Baku’s port, reducing capacity and raising costs.

Cargoes of oil and oil products through the Dubendi oil terminal dropped to 810,000 tonnes in the first half of 2025 from 880,000 tonnes a year earlier, according to Eldar Salakhov, director of Baku International Sea Port. He linked the decline to low water levels and said dredging was essential to keep operations stable.

In 2024, more than 250,000 cubic metres of dredging were carried out at Dubendi. A new dredging vessel, the Engineer Soltan Kazimov, completed in April, will be able to deepen the seabed to 18 metres to maintain port capacity.

Hajiyev warned that the ecological fallout was severe. Wetlands, lagoons and reed beds are vanishing, with sturgeon — already nearing extinction — losing up to 45% of their summer and autumn habitats and being cut off from spawning grounds. Caspian seals are also at risk, as shrinking waters and the disappearance of seasonal ice in the north destroy breeding sites.

“With a 5-metre drop in the sea level, seals lose up to 81% of their breeding sites, and with a 10-metre drop, they are almost completely deprived of suitable sites,” Hajiyev said.

Professor Amir Aliyev, head of the geomorphology of the Caspian coasts and seabed department at the Geography Institute under the Ministry of Science and Education, said the sea’s level has been falling since 1995, losing about 2 metres in 30 years. He attributed this mainly to changes in water balance, noting that inflows from the Volga have decreased by up to 30% due to reduced precipitation in its basin.

Aliyev said the Caspian is currently 29 metres below global ocean level and could drop to 31 metres by 2040–2050. “Pirallahi Island may connect to the Absheron Peninsula as the water recedes, while similar changes are visible near Chilov,” he said. Describing the process as periodic, he noted that sea levels had repeatedly risen and fallen over centuries, with historical records such as Abbasgulu Agha Bakikhanov’s Gulustani-Iram referencing higher waters.

“Although the Caspian behaves like a self-regulating organism, the current annual decline of 10–15 cm reflects the impact of climate-driven shifts in precipitation and circulation patterns,” Aliyev said.