The EU-INTAS/DFG/ Project CLIMAN and a NATO project brought together a multidisciplinary team of scientists, including physical oceanographers, chemists, biologists, palaeoecologists, sedimentologists, geographers, and archaeologists. The primary aim was to assess the impact of climate processes such as controlled by the dynamics of NAO and Eurasian High Pressure features on the Aral Sea ecosystem and on past human populations in the region through teleconnection processes.

Over the last 20 years the Aral Sea is a focus of environmental concern because of dramatic falling lake-water levels and water pollution caused by irrigation in combination with extensive agricultural activities starting in the 1960-ies. However, from a few, high-resolution records covering the late Holocene period it is known that lake-level fluctuations are actually a recurrent phenomenon during the past 5000 to 10000 years. These studies are based on geomorphological evidence and conclusions derived were mainly inferred from paleo-shorelines and paleo-drainage deltas of the Syr-Darya and Amu Darya systems and geochemical evidences. More recent lake lowstands were observed in lake sediments from approximately BC 100–AD 200, AD 800–1250, AD 1500, AD 1600 and since the 1960s. Water balance and biogenic productivity investigations in the Aral Sea sediments showed indeed, that in the Medieval Age lake level were even lower then today (Fig. 1).

The semi arid region of the Aral Sea is a fragile environment. The history of the Aral Sea crisis, one of the World’s worst anthropogenic ecological disasters ever, is well-known. Excessive water use and irrigation diversions have led to rapid shallowing and salinization of the Aral Sea. It is of great importance to formulate a realistic forecast of the future development of the Aral Sea conditions, which could help to elaborate measures aimed to ease the environmental and social impacts. A sound forecast strongly depends on correct account of fluxes that control the water and salt budgets of the Aral Sea system. Such an account should be based on sufficiently detailed “ground truth” hydrophysical and hydrochemical data collected in the lake. Together with Russian and Uzbekian colleagues we collected during different campaings a comprehensive data set describing the present physical state of the Aral Sea, its new chemical composition, 3D spatial distributions and temporal variability of principal physical and chemical parameters, and thereby obtain improved estimates for the constituent fluxes in the physical and chemical budgets of the Aral Sea (Fig. 2). These data will provide a basis for elaborating a sound forecast and identifying measures that could be taken by local authorities and policy-makers.

Partner: Philippe Sorrel, Niklaus Boroffka, Dietmar Kaiser, Bernd Wünnemann, Frank Riedel, Danis Nourgaliev, Anson Mackay, Patrick Austin, Sergey Krivonogov, Karl Baipakov, Timur Shirinov, Sergey Baratov, Nick Aladin

Co-Funding: EU-INTAS, NATO, RFFI