Dynamics of caspian ice in the context of climate change and the prospects for sea ice cover with implications for the habitat of Caspian seals

ABSTRACT The figure of the graphical abstract shows the projections of the spatial distribution of cumulative freezing degree-days for the 2021-2040, 2041-2060, 2061-208, and 2081-2100 periods under the SSP2-4.5 and SSP5-8.5 scenarios. The Caspian Sea is undergoing rapid climatic transformations that pose severe risks to its highly vulnerable ecosystem. The life cycle of the endemic Caspian seal (Pusa caspica) depends critically on the formation and persistence of winter ice in the Northern Caspian. Combining long-term observational data with projections from the BCC-CSM2-MR model within the CMIP6 framework, this study assesses future changes in sea-ice thickness through the end of the 21st century. Results indicate a persistent decline in ice thickness, with an estimated reduction of approximately 30% by the late century. These changes have major implications for the Caspian seal population, which has already experienced a dramatic decline of nearly 90% over the past century. The projected contraction of ice fields is expected to result in the loss of up to 81% of traditional breeding habitats. Beyond biodiversity impacts, diminishing ice cover and associated sea-level changes are expected to trigger cascading environmental, infrastructural, and socio-economic consequences across the Caspian region. The findings highlight the urgent need for coordinated conservation and adaptation strategies, including climate-responsive protected areas, reduced anthropogenic pressure, and strengthened international cooperation.