The analysis of stable isotopes within fluid inclusions represents a powerful tool in reconstructing past environmental and climatic conditions. Fluid inclusions, minute pockets of ancient water trapped within minerals such as speleothems, preserve the isotopic signature of the ambient fluids from which the host mineral precipitated. Laser spectroscopy, in our case using systems developed by Los Gatos Research (LGR),have revolutionized this field by enabling high-precision measurements from micro-scale water samples with minimal preparation. LGR’s Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) combines sensitivity and efficiency, making it ideal for analyzing scarce inclusion fluids. This method has become essential in palaeoclimate studies, enhancing our ability to reconstruct temperature, precipitation, and atmospheric circulation patterns across geological timescales.