As a child, Iranian environmental journalist Maryam spent much of her time by the Caspian Sea. From her coastal home in the northern city of Rudsar, she watched water levels fluctuate; in the 1990s flooding along parts of Iran’s northern shoreline left some relatives homeless.
All that shape-shifting felt normal, yet on a recent return after years away the sea was suddenly unfamiliar.
“I kept walking further from the shore, but the water only reached my knees,” said Maryam, whose real name DW has chosen not to reveal for security reasons. “For someone who grew up by this sea, it was frightening.”
What she saw is part of a wider pattern. The Caspian Sea, the world’s largest inland body of water, bordered by Iran, Russia, Azerbaijan, Turkmenistan and Kazakhstan, is shrinking fast.
Although the brackish Caspian has fluctuated historically, scientists say the current drop in water levels, which began in the 1990s, is unlikely to reverse. Projections point to an even greater retreat this century, with some models indicating potential drops of up to 21 meters (about 70 feet).
“To put that into perspective, an 18-meter drop, for example, would be greater than the height of a six-story building,” said Simon Goodman, an evolutionary biologist at the University of Leeds. “That level of decline would have substantial impacts on ecosystems, as well as on human health, well-being and economic activity.”
Why is the Caspian Sea declining?
Several factors are driving the retreat. About 80% of the Caspian’s freshwater comes from the north via the Volga River. For decades the volume of incoming water has been shaped by dams, irrigation and other water management in the Volga basin. Goodman says the situation ahead is more complex.
“Projections for the rest of this century suggest that ongoing declines will have a much stronger climate change component,” he said.
Rising global temperatures from burning fossil fuels are increasing evaporation from the sea’s surface. Coupled with lower precipitation and reduced runoff into the Volga basin, more water is leaving the Caspian than entering it.
Declining fish stocks, blocked ports
Those changes are already visible, especially in the shallow northern basin along Russia and Kazakhstan. “Many ports around the Caspian require significant dredging to maintain shipping access,” Goodman said, adding such problems “are likely to intensify even within the next five to 10 years.”
Fishing communities are under pressure. Continued decline could make fishing increasingly unviable; if levels drop as far as 10 meters, large parts of the northern basin could dry up entirely, eliminating nearly a third of the sea’s surface area.
In places the process has begun. A site in the northeastern Caspian once used by tens of thousands of seals for spring molting is now dry land. “We are already losing ecologically important habitats due to sea-level decline,” Goodman said.
The effects are visible along Iran’s southern coast as well. With wetlands under pressure, fish stocks have fallen and markets Maryam remembers as vibrant are now shadows of their former selves. A café that once stood at the water’s edge now sits several meters inland.
Could the Caspian face an Aral-style crisis?
Goodman warns there are early signs the Caspian could follow the Aral Sea’s path. Once one of the world’s largest inland lakes between Kazakhstan and Uzbekistan, the Aral has largely dried up due to upstream water diversion, destroying livelihoods and ecosystems and creating health problems from toxic dust storms.
“We are absolutely already at the beginning of that process,” Goodman said. If the northern Caspian were to dry out, exposed seabed could alter the regional climate and release significant dust, some containing pollutants.
Policy action not keeping up with environmental change
Because the Caspian spans five countries, meaningful management will require coordination. Goodman says governments are only at the start of developing collaborative frameworks and that long-term adaptation will need sustained investment in scientific research and strategies addressing both ecological and economic dimensions.
“The pace of policy must match the speed of environmental change,” he said.
Edited by: Tamsin Walker