The regulation of the air: A hypothesis

Abstract

We propose the hypothesis that natural selection, acting on the specificity or preference for CO 2 over O 2 of the enzyme rubisco (ribulose-1,5-bisphosphate carboxylase/ oxygenase), has controlled the CO 2:O 2 ratio of the atmosphere since the evolution of photosynthesis and has also sustained the Earth's greenhouse-set surface temperature. Rubisco works in partnership with the nitrogen-fixing enzyme nitrogenase to control atmospheric pressure. Together, these two enzymes control global surface temperature and indirectly the pH and oxygenation of the ocean. Thus, the co-evolution of these two enzymes may have produced clement conditions on the Earth's surface, allowing life to be sustained. © 2012 Author(s).