The Gaia hypothesis is an ecological hypothesis that proposes that the biosphere an the physical components of the Earth (atmosphere, cryosphere, hydrosphere and lithosphere) are coupled together to form a complex interacting system. This system is proposed to act in a homeostatic fashion that preserves climatic and biogeochemical conditions on Earth that are suitable for living organisms. Named after the Greek Titan of the earth, the hypothesis is frequently described as viewing the Earth as a single organism.