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<p>Significant fluctuations of the Caspian Sea level have been reconstructed for the Holocene. During the Early Holocene, the so-called Mangyshlak Regression lowered the sea level to approximately −&#xa0;90&#xa0;m (Baltic datum) between ca. 11,600 and 8000&#xa0;years BP. In contrast, the Mid- to Late Holocene witnessed the New Caspian Transgression, which raised the level to about –14&#xa0;m. Explaining the genesis of these swings is problematic, since the amplitude of climatic variability in the Caspian basin was insufficiently large to generate such water-budget anomalies. Accordingly, state-of-the-art climate models fail to reproduce the injection or removal of the requisite water volumes in the marine balance. In this study, we are testing the hypothesis that Caspian Sea dynamics may be described by a Gaussian random-noise model. Adopting ± 3σ as the threshold for event likelihood yields fluctuation ranges of 4–13&#xa0;m at different mean levels—magnitudes too small to account for the observed large-scale sea-level events via spontaneous random walks. An exception arises in the −&#xa0;18 to −&#xa0;8&#xa0;m (Baltic) interval, where the potential for internally driven variations markedly exceeds that in other ranges; hence, certain features of the New Caspian Transgression may reflect the chaotic variability of the basin’s hydro-climatic system. Nevertheless, we conclude that internal stochastic dynamics alone could not have produced the major Holocene level changes.</p>

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On the Role of a Random-Walk Mechanism in Holocene Fluctuations of Caspian Sea Level

  • 期刊论文

  • 发表日期：

    2026年5月12日

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  • Alexander Kislov

摘要

Significant fluctuations of the Caspian Sea level have been reconstructed for the Holocene. During the Early Holocene, the so-called Mangyshlak Regression lowered the sea level to approximately − 90 m (Baltic datum) between ca. 11,600 and 8000 years BP. In contrast, the Mid- to Late Holocene witnessed the New Caspian Transgression, which raised the level to about –14 m. Explaining the genesis of these swings is problematic, since the amplitude of climatic variability in the Caspian basin was insufficiently large to generate such water-budget anomalies. Accordingly, state-of-the-art climate models fail to reproduce the injection or removal of the requisite water volumes in the marine balance. In this study, we are testing the hypothesis that Caspian Sea dynamics may be described by a Gaussian random-noise model. Adopting ± 3σ as the threshold for event likelihood yields fluctuation ranges of 4–13 m at different mean levels—magnitudes too small to account for the observed large-scale sea-level events via spontaneous random walks. An exception arises in the − 18 to − 8 m (Baltic) interval, where the potential for internally driven variations markedly exceeds that in other ranges; hence, certain features of the New Caspian Transgression may reflect the chaotic variability of the basin’s hydro-climatic system. Nevertheless, we conclude that internal stochastic dynamics alone could not have produced the major Holocene level changes.