Atmosphere and life

The oxygen cycle is the biogeochemical cycle that describes the movement of oxygen within and between its three main reservoirs the atmosphere, the biosphere, and the lithosphere. The main driving factor of the oxygen cycle is photosynthesis, which is responsible for the modern Earth s atmosphere and life. 

Catling D. and Kasting J. E. (2003) Planetary atmospheres and life. In The Emerging Science of Astrobiology (eds. J. Baross and W. Sullivan). Cambridge University Press, (in press). 

The previous discussion dealt with the solid earth component of the exogenic cycle, a system that is recycled on 10 -10 yr timescales. In contrast, the ocean, atmosphere, and life are recycled at much faster rates and the continuity of the past record is lost rapidly. For quantitative evaluations we have to rely therefore on proxy signals embedded in marine (bio)chemical sediments. 

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