Carbon dioxide is not the only greenhouse gass, there is methane, nitrous oxide, and the fluorinated gasses.
The first person to propose the posibility of silicon based life was a German astrophysicist name Julius Scheiner in 1891.
The oxygen plants, algae, & bacteria create with carbon dioxide in photosynthesis builds a special layer in the atmosphere called the "ozone" which protects Earth's surface from ultraviolet radiation.