Latest data from the Water Research Institute, a subsidiary of the Energy Ministry, show the average water level in the Caspian Sea has dropped by 21 centimeters in 2021, up 19 centimeters compared to the previous year.
The huge decline was principally caused by a substantial increase in lake evaporation that was balanced neither by river discharge nor by precipitation.
The considerable rise in seawater temperature (1.5 degrees centigrade higher compared to that of 2020) exacerbated the critical situation, IRNA reported.
The WRI report shows that the water level’s downtrend is not expected to stop in the foreseeable future.
The average water level decline in the sea was 4 centimeters and 13 centimeters in 2020 and 2019 respectively.
Last year’s measurement put the Caspian Sea’s water level at -27.43 meters (relative to that of the Baltic Sea). The Baltic Sea statistic is used as a reference point to measure fluctuations in Caspian water level.
According to Mohammad Darvish, an environmentalist and a researcher at the Research Institute for Forests and Rangelands based in Tehran, mega structures being developed by the Caspian Sea littoral states (Iran, Russia, Azerbaijan, Kazakhstan and Turkmenistan) on the tributaries of the sea will substantially reduce water inflow into the sea in the long run.
“Close to 200 dams and other huge structures [floodgates and levees] are being built on rivers that feed the sea and would take a toll on the world’s largest lake upon completion,” he said.
“The Volga River (Europe’s largest in terms of discharge that runs through Russia) is the largest tributary of Caspian Sea and provides 85% of its water (260 billion cubic meters a year).”
Water inflow from the Volga River to Caspian Sea amounted to 191 bcm in 2021, down 15% compared to a year ago.
Territorial Waters
Homayoun Khoshravan, the executor of an international plan to monitor variations in the Caspian Sea water level, believes that declining Caspian Sea levels (1.7 meters since 1995) have exacerbated the loss of territorial waters in Iran.
“Satellite-based studies [since 2005] have shown that the level of Iran’s territorial waters is less than the global average and declining gradually,” he said.
“A country's territorial waters are parts of the sea close to its coast, which are recognized by international agreement to be under its control.
In addition to irreparable ecological harm, the lowering water levels in Caspian Sea have led to the shrinkage of territorial waters.”
Khoshravan noted that in some regions around the Caspian Sea, the coastline has reduced by 60 to 200 meters.
“Climate change and global warming are the main culprits behind the lowering water levels in lakes, including Caspian Sea that Iran shares with Azerbaijan, Kazakhstan, Russia and Turkmenistan,” he said.
“Global temperature is increasing and is faster at the poles. As a result, ice sheets and glaciers thaw and water levels in oceans are rising. Global warming has a reverse effect on lakes. It reduces humidity and evaporation in lakes, which result in lowering water levels. The Caspian Sea in no exception.”
The Caspian Sea is a closed water body that was separated from the Black Sea in the Pliocene Epoch (around five million years ago) and has experienced numerous cycles of fluctuations ever since. Its area has constantly changed between 1 million and 150,000 square kilometers, and its water level is estimated to have fluctuated within a range of 300 meters.
The sea experienced a massive drop in water level in the late 1970s but normalized in 1991. However, the water level has been gradually dropping since then.
Caspian water level has decreased by 1.7 meters since 1995 and more decline is expected in the future.
Experts and environmentalists believe that if the shrinkage continues, adverse environmental consequences may occur in Iran’s coastal areas.
The situation cries for action, but possibilities are limited. Rising global CO2 levels, the main driver of climate conditions causing the Caspian crisis, can only be dealt with global agreements.
In Soviet times, large-scale water diversions from Siberian rivers were proposed to deal with the shrinking Aral Sea to the east. But such large works – in the case of the Caspian Sea – come with huge ecological and geopolitical risks.
Nevertheless, action is necessary to safeguard the Caspian Sea’s unique biodiversity and the livelihood of the people who live around it.
