"Caspian Sea hits record low level in 400 years"
The Caspian Sea is at its lowest level for the last 400 years. Itis possible that this indicator will decrease by another 1-2 meters, Deputy Director of the Shirshov Institute of Oceanology of the Russian Academy of Sciences Petr Zavyalov told Izvestia in an interview. According to him, shallowing affects the state of the region's biosphere and its economic development. In order to implement capital projects, accurate forecasts of sea level dynamics are needed, which are not available now. Scientists have developed a set of measures to study the body of water, which will create accurate models to assess the future state of the Caspian Sea.
"The Caspian Sea level decline leads to changes in remote parts of the planet"
- Pyotr Olegovich, is the Caspian Sea a sea or a lake?
- Formally, a lake, but by its properties it is closer to the sea. Physical, chemical and biological processes that take place in it are typical for a sea-type water body. The volume of the Caspian Sea is about 80 thousand cubic kilometers (which is four times the volume of such a sea as the Baltic Sea), and its depth exceeds 1 thousand meters. In addition, the water in the Caspian Sea is salty (although less salty than in the ocean), which also relates it to seas.
- What impact does the Caspian Sea have on the surrounding area?
- It is clear that a body of water of this magnitude cannot help but influence the conditions of its region. It has a mitigating effect on the climate, reducing the heat in summer and the cold in winter. The ecological well-being and life of biological communities both in the water and on land directly depends on the condition of the water area. But there are publications that describe the Caspian Sea's impact on climate on a global scale as well. These "long-range links" are transmitted through atmospheric circulation. Mathematical modeling shows that a decrease in the Caspian Sea level leads to changes in distant parts of the planet. For example, precipitation patterns in the Pacific are changing.
- How does the Caspian Sea participate in the greenhouse gas cycle?
- All seas absorb and release CO2 under certain conditions. This depends on temperature, the state of aquatic and coastal vegetation and other factors. The Caspian Sea plays an important role in this respect. In our country, a special program and a number of full-scale polygons, where the balance of greenhouse gases in nature is studied, have been operating since recently. They try to place them in different landscapes to take into account the diversity of conditions. Surprisingly, the Caspian Sea was not initially included in this program. Now this misunderstanding has been corrected, and in the near future similar studies will be conducted here as well.
- Is the Caspian Sea at its lowest level now? Is it a dangerous situation?
- Indeed, at the moment the average surface level of the Caspian Sea is at about minus 29.5 meters (in relation to the level of the World Ocean). This means that the Caspian Sea has reached a record low level for the last 400 years. It is difficult to predict the further dynamics of the sea level, because the processes determining it - evaporation from the surface, river runoff, atmospheric precipitation - are difficult to take into account with the necessary accuracy. Now some methods of calculations, which used to be used quite successfully for these purposes, are outdated, as temperature, precipitation, wind conditions have changed due to climate change and other factors. New models are needed.
- What further changes in the Caspian Sea level can be expected?
- This is the most important question to which there is no scientifically substantiated answer yet. In my personal opinion, from general considerations we can assume that the level may drop by another 1-2 m, after which stabilization of the level will be achieved, and in the future it is likely to rise back. However, to give an accurate forecast, additional research is needed.
"TheCaspian needs a large research complex with modern equipment"
- What is the importance of the Caspian Sea for our country?
- The climatic and ecological importance of the Caspian Sea has already been mentioned. Besides, this body of water is a part of the transportation corridor from the European territory of Russia and the seas of the Atlantic basin through the Volga to the countries of the Caspian region and further south. The great economic importance of the sea is associated with the extraction of mineral (primarily hydrocarbons) and food resources. Tourism is also promising - the potential of this industry in the Caspian Sea has not yet been fully realized. In addition, it is important for the geopolitical security of the country - it is not by chance that the Caspian Military Flotilla is located there.
In my opinion, nowadays, in scientific terms, Russia's southern seas - the Black, Azov and Caspian Seas - are in a sense "in the shadow" of the northern seas, especially the Arctic seas, in the study of which the state invests more energy and funds. I think that this imbalance needs to be corrected. No reasonable person would deny the strategic importance of the Arctic, but the importance of the southern seas for our country can hardly be overestimated.
- Are there enough funds for scientific study of the Caspian Sea?
- Definitely not. Russia currently has practically no scientific fleet in the Caspian Sea. There are small boats, there are special vessels dealing with certain applied, for example, fishery issues, there is military hydrography, but this is not enough. For fundamental scientific works only a small vessel "Deneb" of the Southern Scientific Center of the Russian Academy of Sciences comes to the Caspian Sea, which is based on the Sea of Azov and every year spends a lot of time crossing the Volga-Don Canal and the Volga River. This situation does not meet the requirements of the time. The Caspian Sea needs a large research complex with modern equipment.
- What can influence the further decrease of the Caspian Sea level?
- In short, the dynamics of the level is completely determined by the water balance of the sea, more precisely, by the ratio between its inflow (water flow into the sea from rivers, precipitation on the sea surface) and outflow (evaporation) components. However, the problem is that we cannot always estimate these components, much less predict their future behavior.
I believe (although not all colleagues agree with me) that it is critical to accurately estimate water losses in river deltas to predict changes. The Volga provides up to 90% of river flow to the Caspian Sea. Contrary to the rather common misconception that the Volga's flow is decreasing due to water withdrawal for domestic purposes, it is actually quite stable at the upstream end of the delta. However, the very variable losses in the delta itself are difficult to estimate. It is a complex system of arms, channels and small water bodies with developed aquatic vegetation.
Some colleagues believe that sea level is significantly influenced by groundwater flow through the sea floor, as well as by tectonic movements of the sea floor itself. These are the most uncertain factors of the water balance, but, in my opinion, their role is still secondary. To say for sure, more research is needed.
"Expedition costs are negligible compared to the losses due to the lack of forecast of the Caspian Sea state"
- What kind of research is needed first of all?
- Some of the data can be obtained from satellites, but for accurate measurements it is important to conduct observations and sampling both in the deep sea and in the coastal zone and river deltas. Such studies will make it possible to clarify the components of the water balance and possibly update outdated formulas.
It should be realized that the costs of measurements and expeditions are negligible compared to the losses due to the lack of forecasting the state of the Caspian Sea.
- How does the lowering of the level affect economic activity?
- Strongly, especially in the shallow northern part of Russia. In particular, cargoes go through the sea, and it is necessary to carry out expensive dredging works to allow ships to pass from the river to the sea. Urban facilities, including recreational facilities, and port infrastructure are also suffering - either new berths need to be built or, again, the seabed needs to be dredged. However, as long as there is no certainty (at least in the form of probabilistic estimates) as to how the sea level will change further, it is risky to make capital investments.
- Does shallowing affect biodiversity?
- Every change in the Caspian ecosystem has a chain of consequences. For example, fish that live in the sea but spawn in the rivers start to have difficulty moving upriver. This leads to population decline, which affects the entire food chain.
The Caspian seal population has decreased by an order of magnitude in recent decades. We cannot say that this is related to sea level changes, but it is clear that these changes affect the living conditions of the population and the state of the food base. The sea level drop has also changed the regime of sea currents, and many plankton species are passively transported by currents - therefore, changes in the sea level will also affect the distribution of these species.
- How do scientists from the countries bordering the Caspian Sea interact?
- The sea is divided into five national sectors between the coastal countries, and to date each country has studied its sector separately. It is a mosaic picture. In the future, we need an international common program that would cover the entire sea area and harmonize research methods.
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