The Caspian’s retreating waters: a slow-burning crisis

The Caspian Sea, the world’s largest inland body of water, is at the heart of the Eurasian landmass. Its unique geography, geostrategic location and ecological importance make it one of the most significant natural features on the planet. The Caspian is situated between the major energy-consuming markets of Asia and Europe and has increasingly become a vital energy and transportation corridor. In recent years, billions of dollars have been invested to connect it more closely to the global economy. New oil and gas pipelines, fiber optic cables and roads and rail lines are increasingly linking the Caspian with East Asia, Europe and South Asia.

The region is extraordinarily rich in natural resources. It contains 43 to 45 billion barrels of proven oil reserves and 575 to 600 trillion cubic feet of proven natural gas reserves, according to the most recent data from national and international sources. These figures rival some of the most productive offshore oil fields globally. Beyond hydrocarbons, the sea is home to more than 100 species of fish, including the endangered beluga sturgeon, from which highly sought-after caviar is sourced.

The Caspian has also long been a source of geopolitical tension. The five littoral states — Russia, Kazakhstan, Turkmenistan, Iran and Azerbaijan — have historically been at odds over how its resources should be managed. Some of these disagreements were resolved in 2018 with the Convention on the Legal Status of the Caspian Sea. However, this agreement left several issues unresolved, especially regarding the delimitation of seabed resources. Maritime boundary disputes also remain between some states.

Another looming problem warrants far more attention: the rapid decline in Caspian Sea water levels. According to satellite imagery and NASA’s Global Water Monitor, its levels have been steadily dropping since the mid-1990s. If current trends continue, the sea could drop by 9 to 18 meters by the end of the century. This represents not only an environmental crisis but a potential geopolitical one as well.

While environmental concerns dominate most discussions, there are also serious geopolitical consequences

Luke Coffey

Several factors contribute to this decline. The Volga River, which provides 80 percent of the Caspian’s inflow, has been extensively dammed and diverted inside Russia for reservoir creation, significantly reducing its contribution. Rising global temperatures have accelerated evaporation and a drier regional climate means precipitation no longer replenishes the sea as it once did. In addition, Soviet-era irrigation systems that are still in use continue to divert water that would otherwise reach the Caspian. These factors, taken together, represent a dangerous convergence of ecological and human-made stressors.

The environmental effects are already apparent. Habitats for fish and marine mammals are shrinking, a problem exacerbated by widespread industrial and agricultural pollution. Some species, such as the Caspian seal and various sturgeons, are already endangered and the risk of extinction will grow if the sea continues to recede. While environmental concerns dominate most international discussions, there are also serious geopolitical consequences to consider. Three stand out.

First is the impact on shipping and energy markets. The Caspian is increasingly seen as a vital transit hub linking Asia and Europe. A loss of navigable water could make regional trade more difficult. The shallowest sections — in the northern Caspian near Russia and Kazakhstan — are particularly vulnerable.

Under the most extreme projections, by 2100 an area roughly the size of Jordan may turn to desert or swamp. Ports in these areas would be unable to accommodate large vessels, pushing trade toward the southern Caspian. This would likely intensify competition for shipping routes and infrastructure. Countries like Kazakhstan, reliant on offshore oil fields such as Kashagan and Tengiz, may face logistical nightmares unless they invest in human-made islands, underwater pipelines or shuttle barges to connect these fields to global markets.

Second is the prospect of changing the region’s naval posture. Russia maintains the largest naval force on the Caspian, with its main base at Astrakhan — a city in one of the shallowest zones. If sea levels were to fall by 18 meters, Astrakhan would no longer be viable as a naval port. It would also sever the Volga-Don Canal route, cutting off Russia’s vital naval connection between the Caspian Sea and Black Sea. This would force Moscow to consolidate its fleet further south in Kaspiysk and Makhachkala, both in Dagestan.

Given the region’s history, it is not far-fetched to imagine new conflicts emerging over resources exposed by a shrinking shoreline

Luke Coffey

Such a shift would not only require massive investment, but it would bring Russia’s military presence further south in the Caspian, potentially raising tensions among regional countries. Furthermore, instability in Dagestan makes it a precarious choice for hosting Russia’s only remaining Caspian naval facilities. In the past, militants have attacked Russian targets located in both cities.

Third, the shrinking sea may reignite border disputes. As the waters recede, newly exposed land could lead to fresh claims and counterclaims, particularly if those areas are rich in hydrocarbons. What were once maritime boundary disputes could turn into contentious land claims. Given the region’s history of unresolved maritime border tensions, it is not far-fetched to imagine new conflicts emerging over resources exposed by a shrinking shoreline.

The Caspian region has always been a zone of competition and strategic significance. The littoral states will undoubtedly bear the brunt of the consequences if water levels keep dropping. But the broader region — and even global markets — could feel the ripple effects. As policymakers focus on urgent flashpoints like Ukraine, Gaza or US-China trade tensions, they must not ignore quieter yet consequential threats. The Caspian’s retreating waters are a slow-burning crisis that could one day erupt into something far more difficult to deal with.

• Luke Coffey is a senior fellow at the Hudson Institute. X: @LukeDCoffey