The Gaia hypothesis, which takes its name from the Greek word for the Earth, was set out by the climate scientist James Lovelock in 1979.
Lovelock initially worked with NASA in attempts to identify whether life existed on Mars.
It was the contrast between the static nature of our neighbouring planet and the dynamism of our own which led to the development of what has come to be known as the Gaia theory.
What is the Gaia Theory?
The Gaia theory regards the earth as, in essence, a single organism, and everything on the planet as a part of that organism. This does not merely mean all living things, or even all organic matter, but postulates that the planet, with its rocks, plants, animals and atmosphere, is essentially what the Gaia Theory website describes as “a single, living, self-regulating system.”
The implications of this are that all the various components of the Earth’s system play a part in regulating the overall biosphere so as to maintain an optimum situation for the living system. Various feedback mechanisms operate so as to maintain the earth as a place where life can continue – for example, atmospheric temperatures have adapted to overcome increasing incoming radiation from the sun.
Temperature is not the only factor affected. The Gaia theory also looks at other variables such as the salinity of the oceans and the hydrological cycle (which affects rainfall). It should be noted, however, that not all scientists accept Gaia without question. A discussion in the Open University course Earth and Life notes that there are distinctions between the balances within organisms and the physical feedbacks which can also operate.
Daisyworld – Demonstrating the Gaia Hypothesis
The Gaia hypothesis can be understood through the simple computer model Daisyworld, which was developed for the purpose. Based on a simple scenario, Daisyworld envisages a world with two types of daisies, black and white. When (for whatever reason) the temperature falls below the optimum level for both types of daisy to grow, the black daisies are able to absorb more heat and so grow more quickly, coming to predominate.
The black daisies, however, absorb so much heat that the atmosphere eventually warms up. As it becomes warmer the white daisies, with their ability to reflect heat and to keep cool, find that they are better suited to the prevailing conditions. They then begin to predominate – reflecting so much heat that the atmosphere cools and the black daisies again begin to thrive.
Daisyworld is, of course, and extremely simple model and the real earth involves far more variables, both in number and in complexity. As the explanation provided by Indiana University notes, what it does is demonstrate the impact of feedbacks and the way in which natural selection can operate to maintain the equilibrium of the earth’s system.
Gaia and the Future
In a world where discussions rage about climate change and the impacts which humans and their activities can have upon the earth’s system and its suitability for life, Lovelock’s position is unambiguous. In an article first published in the Independent newspaper in 2006, he equates himself as the bringer of bad news. He argues that Gaia is quite capable of self-regulation, and that human intervention is taking on a task that is beyond our capabilities.
Climate change – and specifically global warming – is a threat: he warns of a possible temperature rise of 8⁰C in temperate regions and 5⁰C in the tropics. His argument is that human interference, through irresponsible use of resources which contribute to self-regulation, will lead to what he calls “a morbid fever that may last as long as 100,000 years.”
Gaia is not proven, of course, and there is a strong body of opinion which supports the contention that climate change is itself natural and not anthropogenic. But Lovelock and his supporters continue to argue that human meddling in the natural balance of the earth as a system is potentially disastrous and, as he concludes, “we are responsible and will suffer the consequences.”
Gaia Theory. “Understanding Gaia Theory” Accessed 11 May 2011. Indiana University.
“Daisyworld or Gaia redux” Accessed 11 May 2011.
Lovelock, James. The Earth is about to catch a morbid fever that may last as long as 100,000 years. (2006) Accessed 11 May 2011.
Open University. Evolving Life and the Earth (1997).