Researchers from the Massachusetts Institute of Technology and the University of Birmingham have proposed a new tactic for searching for the basis of life on distant worlds. As a basis, they took the Earth, where carbon is the basis of life, but the content of carbon dioxide is only 0.04% of the atmosphere. By comparison, Mars and Venus have about 95%, but there is no life there, and it is directly correlated.
The low concentration of CO2 on Earth is due to the fact that this gas is absorbed by the huge volume of water on Earth. The higher the CO2 concentration, the less water on the exoplanet, and vice versa. But the presence of water alone does not guarantee the origin of life on a cosmic body. This is only a basic marker, for example, because the James Webb Space Telescope is very good at measuring CO2 levels on exoplanets.