Caspian Sea

The Caspian Sea, the largest inland body of water on Earth, holds petroleum and wildlife resources crucial for Eurasia’s economic and political stability. It is a unique waterbody that exhibits some traits of a sea and, in other ways, more resembles a lake.

Caspian Sea Geography

The Caspian Sea, the world’s largest landlocked body of water, is located in central Eurasia. During the Miocene era 26 million years ago, the Caspian Sea was part of a larger sea that included the Black Sea and the Aral Sea before tectonic uplift eventually transformed them into distinct basins. Actually a saltwater lake, the Caspian Sea is bordered by five countries. Kazakhstan lies to the north and east of the sea, while Turkmenistan is also on the sea’s east coast. Azerbaijan and Russia (containing the two autonomous republics of Daghestan and Kalmykia) are on the Caspian Sea’s western border, and Iran is on the southern coast. Known to humans for centuries, the Caspian Sea was called by the ancient Roman name of Caspium Mare. Its proximity to the trade route known as the Silk Road assured its importance as a center of trade and commerce until ships came to dominate trade routes.

Unsymmetrically shaped and somewhat resembling the silhouette of a seahorse, the Caspian Sea’s size varies because it undergoes cycles of contraction and expansion. On average, the sea stretches about 1,200 kilometers from north to south and from 210 to 436 kilometers from east to west, encompassing an approximate area of 371,000 square kilometers. Six rivers feed freshwater into the Caspian Sea, diluting its brine. The Volga and Emba Rivers enter from the north. The Ural River, considered the geographical dividing line between Europe and Asia, also ends at the sea’s northern edge. The Gorgan and Atrek Rivers flow from the east, and the Kura River is the sea’s western tributary. The Elburz and Greater Caucasus Mountain ranges are located south and southwest of the Caspian Sea.

Deepest in its southern part, the Caspian Sea has an average depth of 170 meters. There are two gulfs along the eastern coast, the Krasnovodsk Gulf and the shallow Kara-Bogaz-Gol, which evaporates and leaves salt deposits. Although the Caspian Sea’s level fluctuates yearly, it measures an average of 28 meters below mean sea level. During the 1960s and 1970s, the Caspian Sea’s level was substantially lowered because water that usually flowed into the sea from its tributaries was diverted for agricultural irrigation. In an attempt to stop water loss, engineers built a dike across the mouth of the Kara-Bogaz-Gol in 1980. Instead of creating a long-lasting lake, the dammed-up water evaporated within three years. Subsequently, an aqueduct was necessary to deliver water to the Kara-Bogaz-Gol. Other river and sea dams block both water and fish from moving naturally while protecting oil refineries on land.

Lacking a natural outlet to other large bodies of water, the Caspian Sea is connected by tributaries to adjacent waterways (such as the Black Sea) that can be navigated to reach distant markets. The Caspian Sea’s primary ports are Krasnovodsk in Turkmenistan, Makhachkala in Russia, and Baku on the Apsheron Peninsula in Azerbaijan. The frigid winter climate causes ice to form in the northern parts of the Caspian Sea, hindering travel and fishing. Weather patterns produce dangerous storms, mostly moving southeast across the sea, damaging vessels and oil-drilling platforms. These storms are also hazardous to humans, plants, and animals living in the water, as well as reefs and other geological structures.

Petroleum and Geopolitics

Humans have known about the Caspian Sea’s valuable natural resources for hundreds of years. Thirteenth-century explorer Marco Polo commented that Caspian oil was so plentiful that it gushed like fountains. By the 1870s, speculators equipped with drilling technology became wealthy selling oil, and the Caspian Sea region enjoyed prosperity until the 1917 Russian Revolution, when oil barons were arrested and their wells seized. Caspian Sea oil was considered a strategic raw material during both world wars. Soviet leaders abused Caspian oil production, negligently removing oil with inadequate tools and polluting adjacent areas in the process. Because the Caspian Sea contains substantial petroleum deposits, international competition to secure this valuable fuel resource was the catalyst for an oil rush in the late twentieth century that filled the sea with oil derricks.

The largest known oil deposits in the Caucasus region and Central Asia are located in the Caspian states of Kazakhstan and Azerbaijan. Geologists surveyed three major areas of petroleum lying in deposits that began about 3,600 meters beneath the Caspian Sea’s surface. Although the size of these deposits was not immediately determined, their potential seemed to rival the measured deposits of other oil-producing countries. One of the primary deposits is underneath the Caspian Sea. The others are onshore. The second deposit reaches eastward from Baku to Turkmenistan. The third area spreads west of Kazakhstan underneath the sea’s northern tip. The Caspian Sea’s oil offered an alternative petroleum source to countries relying on Persian Gulf reserves.

As oil exploration increased in the region in the twentieth century, experts suggested that almost 200 billion barrels of oil remained in the Caspian Sea area. On average, 1.1 million barrels were removed daily, in addition to by-products of sulfur. The area is also rich in natural gas, with estimates of 7.89 million cubic meters in the late twentieth century, and gas extraction grew rapidly along with petroleum operations. During the 1990s, European and American oil companies such as Amoco (later part of BP) and Chevron secured agreements with the governments of several of the countries bordering the Caspian Sea to invest money, equipment, and labor to build pipelines and extract petroleum. Local institutions such as the Azerbaijan State Oil Academy prepared workers for the technical demands of oil extraction. Geologists rely on seismic imaging to analyze the Caspian Sea for petroleum. Drillers encountered problems with currents and mud volcanoes on the sea floor, and scientists developed refined technology and geophysical extraction methods to locate and remove oil from deep reservoirs of hydrocarbons existing at high temperatures and pressures.

Investors were aware of political and social tensions in the Caucasus region and carefully planned to place pipelines to avoid territorial claims on oil. Competing commercially for the oil, foreign nations strove to achieve strategic alliances and consider diplomatic consequences. They were aware of the vulnerability and instability of many Caspian Sea countries. Several treaties were signed by the littoral Caspian states to legally divide the sea into zones for each state to claim resources. These nations encouraged competition to boost prices because access to Caspian Sea energy resources became an urgent post-Cold War geopolitical objective. Such considerations continued to shape economic and political realities in the region into the twenty-first century, as fossil fuel extraction remained a key economic driver.

Flora, Fauna, and Overfishing

The Caspian Sea and its surrounding lands provide habitats for an eclectic assortment of wildlife and plants that enhance the area’s environment and economy. The sea’s primary water source, the Volga River, forms a swampy delta near the confluence of the sea. This marsh is home to waterfowl, including ducks, swans, flamingos, and herons, as well as eagles that rely on the wetlands for shelter and food. Along parts of the uninhabited eastern shore, camels thrive, and wildflowers grow among reeds on the dunes. Fish living in the Caspian Sea include salmon, perch, herring, and carp. The sea is also home to seals, tortoises, and crustaceans unique to the region.

Among the most significant wildlife are the several species of sturgeon found in the Caspian’s salty water. Among these, the Beluga sturgeon stretches as long as 4 meters and weighs 1,000 kilograms, the Russian sturgeon (Ossetra or Asetra) is about 2 meters long and weighs 200 kilograms, and the starry sturgeon (sevruga) is just over 1 meter in length and weighs approximately 25 kilograms. Approximately 90 percent of the global sturgeon population lives in the Caspian Sea, producing what gourmets consider the world’s tastiest caviar. Eggs compose as much as 15 percent of a sturgeon’s weight.

Russian czars generously served Caspian caviar, and Soviet and Iranian entrepreneurs became wealthy exporting the processed sturgeon eggs for hundreds of dollars per ounce. To maintain a monopoly and keep prices high, these countries carefully controlled fishing and cultivated sturgeon in fisheries to replenish the population. After the collapse of the Soviet Union in 1991, sturgeon poaching became a serious problem threatening the Caspian Sea ecosystem. Nineteenth-century Russians reported yearly catches of 50,000 tons of sturgeon. In the 1980s, the Soviet Union caught as much as 26,000 tons of sturgeon annually, according to statistics maintained by the Caspian Fishery Research Institute. By the late 1990s, only 3,000 tons of sturgeon were reported to be harvested by commercial anglers from Caspian countries each year due to sharp declines in the population and legal restrictions on fishing.

However, reducing the allowable sturgeon harvest did not solve the overfishing problem. Motivated by potential profits and desperate economic conditions, Caspian anglers poached sturgeon to survive financially by selling fish eggs and meat. One ounce of caviar often sold for more than ten times the amount of an individual’s monthly salary. Poachers also saved portions of fish to feed their families. Placing nylon line traps beneath the surface of the Caspian’s tributaries, poachers waited for spawning sturgeon to swim upstream. Such uncontrolled snaring reduced the sturgeon population to the point that it was eventually considered endangered. Experts stressed that overfishing resulted in the deaths of approximately 90 percent of sturgeons too immature to spawn (most sturgeons require an estimated eighteen years to develop reproductive capabilities), which detrimentally reduced the number of fish returning to the Caspian’s rivers every year. Fewer Beluga sturgeon were captured annually, and few reached their potential to be as heavy as 1 ton and survive for a natural one-hundred-year life span. Despite ongoing efforts to reduce fishing, increase aquaculture, and otherwise regulate the fisheries industry, these environmental threats remained an important issue into the twenty-first century. In the mid-2020s, the sturgeon is considered a critically endangered species, and in 2019, the Caspian Sea nations renewed a ten-year moratorium on sturgeon fishing.

Environmental Issues

Pollution also poses substantial dangers for sturgeon and other wildlife. The Caspian Sea has been contaminated by oils and petrochemicals from drilling platforms, as well as by pollutants and industrial residues dumped into rivers by factories. Careless drilling methods caused oil films as thick as 6 millimeters to float on the Caspian Sea, creating an unhealthy environment for fish. Raw sewage was also discharged from drains into the sea’s tributaries. Scientists in the late twentieth century found that the waters near the cities of Baku and Sumqayit were so saturated with poisonous wastes and were so depleted of oxygen and nutrients that they could not harbor aquatic life.

The Caspian Sea benefits from the marshes in the Volga River’s delta, which strain out some debris and contaminants before the water reaches the sea. Near the river’s mouth, which consists of thousands of slender streams moving through the stalks of indigenous water plants, the Caspian Sea’s shallow pools of sparkling blue water seem clean. However, moving toward the sea’s interior, the water becomes murky and appears gray in color.

Experts warn that the Caspian Sea is experiencing an environmental crisis that will only worsen as the extraction of natural resources increases and industrialization expands in bordering countries. Authorities have blamed these pollutants for contributing to the growing rates of miscarriages and stillbirths in Caspian nations, and industries are now encouraged to reduce pollution and cease using rivers for effluent disposal. Petroleum companies operating onshore oil fields and platforms in the Caspian Sea have been advised to adapt their operations to rigid standards regarding drilling to prevent tainting the water with contaminating fluids and detritus.

Ecologists want extractors of natural resources to become more aware of their impact and accountability to maintain the Caspian Sea’s environmental quality. Scientists demand that bans on poaching and illegal caviar processors be enforced more diligently, with police monitoring the sea and arresting offenders. They also seek to prohibit open-sea fishing, which kills young sturgeon, and recommend that Caspian Sea nations agree on caviar quotas to set fair prices to discourage black-market profiteering and poaching. Public relations campaigns continue to promote public knowledge of the Caspian Sea’s environmental crises and provoke more responsible treatment of its resources.

Changing Sea Level

The Caspian Sea is well known for its periodic variation in water level, which is affected by various factors as the water body is a self-contained system subject to rainfall and evaporation. Biologists monitoring the sea noted that after a lengthy period of contraction, its average level rose 2 meters from the late 1970s to the 1990s. Some researchers optimistically believed that the increased amount of water might weaken the effect of pollutants on the sea and its inhabitants unless the amount of toxic material and oil spills entering the sea drastically increased. Many scientists speculated that global climate change might have contributed to rising sea levels.

Other scholars hypothesized that the water level increases might have been caused by natural processes, possibly initiated by climatic deviations that affect the atmosphere and sea over periods of years, decades, or longer periods. Scientists in the early twenty-first century have suggested that such trends, together with the broader effects of anthropogenic climate change, are likely to contribute to a marked decline in the sea level moving forward. System modeling pointed to evaporation as the driver of sea level decline observed from 1996 into the 2010s, leading to fears of a similar situation to the Aral Sea desiccation. In the early 2020s, scientists, based on studies and satellite images, warned that due to climate change, water levels in the Caspian Sea could drop a further 8 to 30 meters by the year 2100. Depending on the level of human activity in the region, this number could increase by an additional 7 meters.

The erratic changes in the sea’s composition and contents that were documented in the past and that periodically recur will crucially affect the future development of the Caspian Sea’s resources. The quantity and quality of the Caspian Sea’s water are vital to ensure Eurasian economic and political stability and to maintain international technological and business interests in the region. In the third decade of the twenty-first century, the Caspian Sea remained in an environmental crisis with its water levels at the lowest ever recorded at 29 meters below sea level. These record-low water levels threatened the biodiversity of the Caspian Sea and caused socioeconomic issues for the populations living along its waters. To adequately address these issues, the surrounding nations attempt to work together in an international environmental effort to mitigate the damage to the Caspian Sea. However, geopolitical factors, such as the war in Ukraine, often pose a challenge to this process. 

Principal Terms

littoral: adjacent to or related to a sea

petrochemical: a chemical substance obtained from or derived from natural gas or petroleum

petroleum: a naturally occurring liquid composed of hydrocarbons found in Earth’s subterranean strata and used as fuel by humans

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