The true magnitude of CO₂ emissions from volcanic activity is poorly constrained, limiting our understanding of the natural carbon cycle. CO₂-sensitive lidars could be used to measure the distribution of CO₂ in a volcanic plume, thereby allowing volcanic CO₂ fluxes to be measured directly. The recently begun ERC research project CO2VOLC aims to produce such an instrument based on the differential absorption lidar (DIAL) technique. In this paper we investigate the ON and OFF wavelengths which offer optimal CO₂ detection and identify the spectral requirements of the lidar transmitter, in the context of commercially available solid-state laser sources.