The Caspian Sea has lost an area nearly the size of Sicily: human activities are a major reason why

The Caspian Sea is shrinking dramatically, and researchers say the main driver is human activity rather than a natural climate cycle. Using satellite observations and river hydrology records from Iran, Russia, Turkmenistan, Azerbaijan, and Kazakhstan, the study found that inflow to the Caspian has fallen sharply over the past three decades. Rain over the Volga Basin—supplying about 80% of the sea’s inflow—has slightly increased, undercutting the idea that reduced rainfall alone explains the downturn. Evaporation is rising due to higher regional temperatures, but it accounts for only about 40% of water loss since the mid-1990s.

Since the mid-1990s, the Caspian has lost roughly 24,000 km² of surface area, about the size of Sicily, and water levels have dropped around two metres. The shallow northern Caspian, described as ecologically highly productive, is drying fastest. The paper links retreating water to worsening ecological conditions, including a long-term rise in chlorophyll-a concentrations, a marker of algal activity and declining water quality. The study points particularly to river engineering, such as dams, irrigation withdrawals, and the Volga–Don canal system that diverts water toward the Black Sea via Russia’s waterways.