An Introduction to Gaia Theory

Background Facts and Information

Many people today would associate the phrase Gaia Theory (or, if you prefer, Hypothesis) with New Age, pagan or paranormal topics. In fact when it was first proposed Gaia had none of those associations. It was - and still is - a respectable mainstream theory.

James Lovelock

The scientist most associated with Gaia Theory is James Lovelock. He first stated the hypothesis in 1972 in the journal Atmospheric Environment journal.

Essentially the theory involves viewing the Earth not as a collection of disparate systems but on a more holisitc level. Our planet - and all the life on it - is part of one huge, self-regulating system.

Lovelock defined Gaia as:

"a complex entity involving the Earth's biosphere, atmosphere, oceans, and soil; the totality constituting a feedback or cybernetic system which seeks an optimal physical and chemical environment for life on this planet"
Thus life and the side-effects of life influence and are influenced by the environment. This creates a feedback mechanism that is largely self-regulating. For example, if the atmospheric levels of carbon dioxide rise then more plants grow - which remove more carbon dioxide from the atmosphere.

It is interesting to note that since life on Earth began the heat from the sun has increased by 25%. Yet in all that time the actual surface temperature has remained near constant. This suggests that there must be some form of control mechanism.


A thought-experiment concerning the validity of the Gaia hypothesis is the Daisyworld model. This depicts an extremely simple ecosystem consisting only of black and white daisies, along with an increasing solar temperature. Computer models show that Daisyworld does indeed respond in line with Gaia theory. Obviously the real world is orders of magnitude more complex than Daisyworld, however the success of this simulation suggests that the Gaia hypothesis is viable.

Unfortunately in Daisyworld even the Gaia effect eventually breaks down when put under enough stress. With our current levels of pollution and environmental damage we should bear that in mind. Any cybernetic system will break if you push it too far.

Are we on the verge of killing Gaia?

Lovelock has been careful to stress that at no time was he proposing a sentient Gaia. However others have been attracted to that concept and have proposed various forms of strong, mystical Gaia hypotheses.

External Links:
James Lovelock UN Lecture