Stable isotopes in cave ice reveal Holocene changes in mountain snowpack sublimation

Mountain snowpacks are influenced by sublimation, with direct implications for water availability. We constructed a record of sublimation efficacy from perennial ice within Bear Ice Cave (Utah, USA). Radiocarbon dating of organic matter indicates that ice accumulation began before ca. 5500 cal yr B.P., and the youngest ice formed ca. 600 cal yr B.P. Direct observations, hydrochemistry, and soil moisture time-series indicate that the ice originated from snowmelt that reached the cave through the epikarst. Values of δD and δ18O increase upward through the ice, whereas d-excess decreases. Given the source of the water, this pattern implies that sublimation from the winter snowpack has become more effective over time. These results demonstrate that cave ice can archive a fingerprint of sublimation, offering a window into long-term changes in snow−atmosphere coupling.