Only a few things are known about our beloved planet's incredibly complex functionality. The Gaia1 theory of James Lovelock2 emerged in the 1970s as an attempt to describe the entire system of living organisms, weathering, soil, climate, and interactions between it all, as one unity. It mainly focuses on the fluxes and interactions between the parts of the whole system which is described as Gaia, and its ability to regulate its determining processes.
Lovelock (among many other geophysiologists) believes in an active system, regulating its surrounding parameters and therefore being able to adapt to changes in solar and geological changes. It is of fundamental importance for an understanding of the self-regulation of the climate system, an attempt of describing the ice ages, and the ability of living communities to survive major impacts.
Lovelock used a theoretical world, 'Daisyworld', to show how these processes may work. He described an artificial world only populated by daisy plants. Due to variation in their colour, and therefore in an important parameter interacting with the flux of solar energy, he showed how a system can adapt to an increase in solar input by actively changing the amount of reflection back to space. The daisy population itself keeps the global temperature at a nice and enjoyable level. Further investigations discovered the influence of vegetation on cloud development, and many other scientific stuff, and lead to the conclusion that the healthiest state of the earth as a system is that of an ice age with low CO2 concentrations. 'Perhaps Gaia likes it cold.'
For anyone who ever wondered how this planet managed to survive major impacts like meteors and mankind, Lovelock's book is a lovely one, easy to read, even for non-geographers and non-ecologists.