Raman spectroscopy offers many advantages for ice core research. Besides the conventional use case of identifying crystalline microinclusions in the ice, other applications have evolved over the last years. Ice cores are the only climate archives incorporating palaeo-atmosphere as air inclusions (bubbles and crystalline hydrates) in the ice matrix. Confocal Raman spectroscopy is the only method capable of determining gas mixing ratios in individual air inclusions in the ice, a great advantage for the research of atmospheric composition and the role of greenhouse gases in the past climatic stages. A firm understanding of these processes is needed for reliable predictions of future climate variability. The invention of the new AWI Cryo-Raman system, where the microscope stage is set up inside the cryolab, enables long time measurements and mapping techniques that have not been available for ice samples before. Cryo-Raman tomography allows for the first time to determine accurate 3D structures of natural air hydrates in Antarctic ice cores. The 3D reconstructions show complex growth structures that are not accounted for by the available models of hydrate formation. A better understanding of these formation processes will enhance the knowledge about gas diffusion processes in the ice and will help to interpret controversial features in the gas records.