The Caspian Sea, the world’s largest inland body of water, faces a significant decline in its water levels. This immense lake, bordered by five countries, functions as a closed basin with no outflow to oceans. Recent observations reveal a continuous drop in its surface, signaling an environmental shift with widespread implications for the region.
The Shrinking Caspian Sea
The Caspian Sea’s water levels have declined significantly in recent decades, reaching historic lows. Since 2015, the sea’s water level has fallen by nearly 80 centimeters, continuing a drop observed since 1995 and accelerating since 2006. The current water level is more than 29 meters below the Baltic Sea, compared to the past century’s average of 26 to 27 meters.
This shrinkage is particularly evident in the shallow northern areas bordering Russia and Kazakhstan, where large expanses of the seabed are now exposed. For example, the northeastern part in Kazakhstan saw a 39 percent decline in surface area and a shoreline retreat of 37.25 kilometers between 2001 and 2022. Projections indicate that by the end of the 21st century, the Caspian Sea’s water level could drop by an additional 9 to 18 meters, potentially reducing its total area by a quarter.
Drivers of Water Loss
The primary factors contributing to the Caspian Sea’s desiccation are climate change and human activities. Rising air temperatures over the sea have led to increased evaporation. Between 1979 and 2015, the average annual surface air temperature over the Caspian Sea increased by approximately one degree, intensifying this process.
Changes in precipitation patterns within the Volga River basin, which supplies over 80% of the Caspian Sea’s freshwater, also play a significant role. The Volga’s annual discharge has declined in recent years, falling to between 210 and 232 cubic kilometers, below its historical average of 250 cubic kilometers. Scientists estimate that a consistent annual flow of about 270 cubic kilometers from the Volga is necessary to restore the sea to levels observed between the 1970s and 1990s.
Human activities further exacerbate water loss through extensive abstraction from feeder rivers, particularly the Volga. This abstraction is primarily for irrigation, industrial uses, and hydroelectric power generation. Over 14,000 dams have been constructed across the Caspian Sea catchment over the past 90 years, with a collective storage capacity exceeding 75% of the total discharge into the sea. These projects are estimated to have lowered the Caspian Sea’s water level by approximately 1.5 meters compared to natural conditions.
Widespread Impacts
The receding water levels of the Caspian Sea are causing diverse consequences across ecological, economic, and social spheres. Ecologically, the shrinking sea threatens its unique biodiversity, including endangered species like the Caspian seal and various sturgeon species. The exposure of vast areas of the shallow northern seabed, biologically rich ecosystems, destroys coastal habitats and alters salinity levels.
Economically, the decline affects the fishing industry, with dwindling catches and the disappearance of some species due to habitat loss and pollution. Port operations face reduced navigability, necessitating dredging and increasing operational difficulties, which impacts maritime trade and transport. Oil and gas extraction infrastructure also faces challenges due to decreasing water depths.
Socially and geopolitically, coastal communities face displacement and reduced access to freshwater. There is also potential for increased regional tensions over shared water resources and changes in maritime borders among the five bordering countries. The shrinking sea impacts food security and livelihoods for the more than 10 million people living along its coast.
Efforts and Outlook
Addressing the Caspian Sea’s decline requires coordinated efforts among the bordering nations. International cooperation initiatives and research programs are underway to understand and mitigate the situation. The Tehran Convention provides a platform for the five Caspian states to discuss mitigation and adaptation strategies, including adaptation plans and enhanced scientific collaboration.
Azerbaijan, for instance, has proposed convening a summit to address the crisis and is integrating artificial intelligence into national programs to improve forecasting and scenario modeling. The complexity arises from the five littoral states—Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan—each with diverse interests and economic reliance on the sea. While immediate reversal is unlikely, ongoing scientific monitoring and discussions aim to identify sustainable practices and solutions for the sea’s future.