Gaia Hypothesis

IN THE EARLY 1960s, scientist James Lovelock was invited by the National Aeronautics and Space Administration (NASA) to participate in a scientific research project aimed at trying to find evidence of life on Mars. His job was to design instruments capable of detecting the presence of life that could be sent on a spacecraft to Mars. This led him to think about what constitutes life, and how it can be detected. This culminated, in 1979, in the publication of his book Gaia: A New Look at Life on Earth. His hypothesis was that the Earth itself was a live organism. The term Gaia was borrowed from Greek mythology, where Gaia is the goddess of the Earth. Lovelock's thesis is that the Earth is self-regulating and that the physical and chemical condition of the Earth, as well as the oceans and atmosphere, are kept fit because the Earth, or Gaia, is actively regulated by life itself. The Gaia hypothesis is based on the belief that Gaia evolves according to Darwinian laws of self-selection. The Gaia hypothesis does not see the Earth as a sentient organism; rather, that Earth and all the systems on it are finely balanced and interrelated to create the conditions conducive to life on the planet.

According to the Gaia hypothesis, even if all human life on Earth is extinguished, the planet will self-regulate to maintain its own life, and possibly other forms of life within it. For example, Lovelock highlights the resilience of some species of blue-green algae, which are highly resistant to short-wave, ultraviolet radiation. Life overall is robust, even if humans are not. Lovelock identifies three crucial characteristics of Gaia. The first is the tendency to keep constant conditions for terrestrial life forms. This tendency predates the arrival of humans, and he argues that as long as the planet's natural homeostasis (equilibrium) is maintained, the planet will continue to survive as a whole. He argues that the history of the Earth's climate proves his theory that Gaia is a living organism, stating, “if the Earth were simply a solid inanimate object, its surface temperature would follow the variation in solar output.”

Second, Gaia has vital organs at the core, as well as ones on the periphery. Lovelock argues that it is human interference with the vital organs that will determine whether or not the planet will survive. He believes that Earth can survive without 30 percent of its surface. However, he argues it is possible that the world's carbon sinks and microscopic creatures may be vital organs, due to the key role they play in maintaining the balance of the Earth's systems. Maintaining the balance within the oxygen-carbon cycle is vital to life. Other core regions within Gaia include the region between the latitudes 45 degrees north and 45 degrees south, which include the world's tropical forests and scrub lands. Any disruption of these areas may sustain perturbations so drastic that the planet will not survive.

Lovelock argues that the third characteristic of Gaia is the way in which the planet obeys the laws of cybernetics. Gaia's response to major changes to equilibrium will obey the laws of cybernetics, where the time constant and loop gain are important factors. Lovelock points to the fact that despite the Earth revolving around the sun, its mean temperature has never varied by more than a few degrees from its current levels. Thus, it has never been too hot or cold for some form of life to survive on the planet, despite changes to the early atmosphere and variations in the sun's output of energy. This is because the Earth has been able, through the law of cybernetics (as with all living creatures) to self-regulate, which includes instigating the processes of self-correction in the event of any imbalance. However, increasingly, the planet is facing pressure that may disrupt its ability to self-regulate and recover from factors that cause imbalance to the systems within it. Lovelock argues that the disadvantage of such systems is that while they may experience major change, the period within which they manifest that change is so long that there will be [Page 437]lag time between the effect and action to mitigate it. In his second book, The Death of Gaia, Lovelock is very pessimistic about the outcome of this lag, arguing that in relation to climate change, a failure to take action before the full effects of the problem are seen will have disastrous consequences for life on Earth.

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