Glacier Volume Changes Across the Greater Caucasus Between 1960 and 2025

Mountain glaciers are sensitive indicators of climate change and provide essential freshwater resources for downstream ecosystems and human societies. Although glacier area changes have been extensively investigated in the Greater Caucasus, no long-term assessments of regional glacier ice volume reconstruction have been made. This study presents the first comprehensive reconstruction of glacier ice volume changes across the entire Greater Caucasus over the past 65 years, integrating glacier inventories at five observational periods (1960, 1986, 2000, 2014, and 2025) with the automated PalaeoIce reconstruction framework. Total glacier ice volume declined from 88.08 ± 4.5 km3 in 1960 to 42.66 ± 1.1 km3 in 2025, corresponding to an overall loss of more than half of the Caucasus glacier volume (51.6%) since 1960. Ice volume loss accelerated markedly after 2000, with the most rapid decline (27% or −2.45 yr−1) occurring between 2014 and 2025. Spatial patterns in ice volume change show pronounced regional variability. Relative ice loss over the past 65 years was greatest among glaciers in Azerbaijan, which experienced a 98.4% reduction in ice volume. In comparison, glaciers in Georgia and Russia lost 52.6% and 50.9% of their ice volume, respectively, over the same period. Sectoral analysis further reveals contrasting spatial responses across the Greater Caucasus, with the eastern sector experiencing the greatest proportional ice loss of 71.6% over the 65-year study period, followed by the western sector with 60.4% and the central sector with 47.3%. Glacier thickness also declined across the Greater Caucasus over the 65-year study period. Mean glacier thickness decreased from 28.2 ± 1.41 m in 1960 to 17.4 ± 0.75 m in 2025, while mean maximum thickness declined from 88.7 ± 4.44 m to 54.1 ± 2.33 m over the same period. These findings provide region-wide quantification of long-term glacier ice volume and thickness evolution in the Greater Caucasus and establish an important baseline for assessing glacier response to ongoing climate change, future water availability, natural hazards, and regional cryospheric evolution.