Gaia hypothesis
The Gaia hypothesis holds that biological processes work to maintain a stable surface climate on Earth to maintain habitability through various negative feedback mechanisms. While organic processes, such as the organic carbon cycle, work to regulate dramatic climate changes, and that the surface of Earth has presumably remained habitable, this hypothesis has been criticized as intractable. Furthermore, life has existed on the surface of the Earth through dramatic changes in climate, including Snowball Earth episodes. There are also strong and weak versions of the Gaia hypothesis, which has caused some tension in this research area.