Gaia vs the biosphere

Gaia

name
  • The ecosystem of the Earth regarded as a self-regulating superorganism. 

  • A Greek goddess, the personification of the earth, and one of the primordial deities from whom all the others descend. 

the biosphere

How often have the words Gaia and the biosphere occurred in a corpus of books? (source: Google Ngram Viewer )