The head of Iran’s meteorological center has said that the level of the Caspian inland sea has dropped by 1.5 meters (5 feet) in the past 26 years.

Behzad Layeghi told local media that the sea level is dropping by an average of 6 cm per year, which is a significant change according to him. Iran has set up monitoring stations along its shorelines.

The Caspian is a salt water inland sea and the largest lake in the world.

Layeghi said that part of the reason is direct human activities such as river water use for other purposes, but the main cause for sea’s retreat of the Caspian is less precipitation. He added that Russian’s Volga River provides 85 percent of the water flow to the Caspian Sea.

The Iranian official said there could be many reasons for less precipitation in the Caspian basin but the most notable is climate change. He added that the huge loss of water can only be explained by climate change and direct human activities could not cause such a drastic change.