Stable, radiogenic, and radioactive isotopes are fundamental tools for understanding Earth’s climate system. Isotopic measurements trace the chemical reactions, mass transfers, and biogeochemical cycles that link climate to other components of the Earth system, and they underpin many past climate reconstructions. Analytical advances, such as triple oxygen isotopes and compound-specific isotope analysis, are opening new avenues for scientific study, while established isotopic methods are steadily being applied to new archives and environmental settings. This session welcomes researchers developing and applying isotopic tools for past and present climate studies. We encourage contributions presenting new analytical methods, calibration and proxy advances, applications to new or underused archives, and modern studies that improve the interpretation of isotopic records. We also welcome studies that integrate isotopic data with geochemical, geomorphic, or climatological evidence, including multi-proxy archive studies, or with modelling approaches such as source mixing and isotope-enabled climate models.