  Environmental research aimed at monitoring and predicting O2 depletion is
still lacking or in need of improvement, in spite of many attempts to find a
relation between atmospheric gas content and climate variability. The aim of
the present project is to determine accurate historical sequences of the
atmospheric O2 depletion by using the telluric lines present in stellar
spectra. A better understanding of the role of oxygen in atmospheric thermal
equilibrium may become possible if high-resolution spectroscopic observations
are carried out for different airmasses, in different seasons, for different
places, and if variations are monitored year by year. The astronomical
spectroscopic technique involves mainly the investigation of the absorption
features in high-resolution stellar spectra, but we are also considering
whether accurate measures of the atmospheric O2 abundances can be obtained from
medium and low resolution stellar spectra.
