July 20, 2026. A team of researchers has studied the reduction in the area of the Caspian Sea and the Kara-Bogaz-Gol Bay for the period 1993–2025 – phenomena associated with the declining level of the Caspian Sea.

The developed methodology, based on the analysis of high-resolution satellite data, made it possible to estimate the surface area of the Caspian Sea and understand how it changes depending on the water level. The resulting modern hypsometric curves for the Caspian Sea and its bay, which relate the area and water level in the water bodies, will help determine the real losses in the sea's surface area, promptly assess further reductions in the area of the sea and the bay, and use this data for calculations of evaporation from the sea surface.

The results of the study, supported by a grant from the Russian Science Foundation (RSF) No. 23-77-00027, have been published in the journal Current Problems in Remote Sensing of the Earth from Space. The lead author is Professor, D.Sc. Andrey Kostianoy, Leading Research Scientist at the Geophysical Center RAS and Chief Research Scientist at the P. P. Shirshov Institute of Oceanology RAS.

Water surface area based on averaged data for June–August (according to Landsat data): (a) Caspian Sea; (b) Kara-Bogaz-Gol Bay.