Quantifying quaternary climate variability in the Southern Caucasus using land snail shell isotope transfer functions and climatic niche modeling

Late Quaternary loess-paleosol sequences in the Armenian highlands represent key terrestrial archives for reconstructing past climate variability. Related proxy data are essential both for understanding the environmental and cultural history of the Caucasus area - a global biodiversity hotspot and archaeological key region - and for benchmarking Earth system models. However, robust quantitative paleoclimate records remain scarce for this climatically and topographically complex area. Here, we present a combined approach integrating (1) stable isotope analysis (δ 18 O, δ 13 C) of land snail shells with transfer functions build on modern calibration datasets and (2) probabilistic climatic niche modeling. For the latter, assemblage-weighted climatic optima are derived from species-specific response curves based on modern species distribution data. Our results reveal predominantly xerophilous faunas associated with colder glacial phases, and mesophilous high-grass to forest-steppe assemblages during interstadial and interglacial intervals. δ 18 O shell was used to reconstruct δ 18 O precipitation signals, which in this study area strongly correlate with temperature. Growing season temperature estimates, based on modern empirical relationships, suggest a mean difference of ∼4.9 °C between glacial minima and interglacial maxima, while precipitation reconstructions from climatic niche modeling suggest a shift from ∼511 mm to ∼770 mm. This study provides the first mollusk-based quantitative reconstructions of Late Quaternary temperature and precipitation in the Caucasus area, demonstrating the potential of integrated mollusk proxies as powerful tools for resolving glacial-interglacial climate dynamics. • Land snail shell isotopes and climatic niche modeling provides new insights into Late Quaternary climatic conditions. • First mollusk-based quantitative reconstructions of temperature and precipitation for the Southern Caucasus. • Palaeoclimate reconstructions indicate glacial-interglacial growing season temperature contrasts of up to ∼5 °C. • PDF-based climatic niche modeling indicates a shift from ∼511 mm during glacial minima to ∼770 mm during interglacial maxima.