un grew brighter, the excess carbon dioxide was converted to massive amounts of vegetation across the globe (what is known as the Carboniferous epoch). This plant matter then was buried through geological processes, creating the quantities of oil and coal found underground. The sequestration of this carbon cooled the Earth.
In the modern era, these stockpiles of carbon have been released by human actions, reigniting the greenhouse effect, warming the Earth again, and disrupting the "preferred equilibrium". The Gaiasphere's reaction, according to one
stupid movie hypothesis, will be the stoppage of the Gulf Stream, causing considerable cooling of the North Atlantic and mainland Europe. The resultant ice age should increase Earth's albedo (brightness), thereby reflecting more solar energy and causing worldwide cooling: and thus the balance would be restored.
The main problem with the above scenario is the lack of any known (or even proposed) mechanism by which biological change could be directed in order to achieve a particular result. Granted, Earth is an incredibly complex mess of interconnected systems, but the equilibrium they achieve is in no way deliberate. When something disrupts the balance (and, really, it's always in slight flux), things change, and a new balance is achieved. The system only looks tuned for life because we're a product of said system.
Complex systems routinely involve negative feedback loops that maintain equilibrium in the system, resembling homeostasis, without any directing force being necessary. To this extent, the Gaia hypothesis does not offer anything new; the idea that the biosphere is composed of highly interconnected, interdependent, and non-isolable systems, operating in dynamic equilibrium, is non-controversial in the hard science (as opposed to the woo) of ecology.
To go some way towards countering criticism of his first book's lack of a plausible mechanism, Lovelock's proposed the model of Daisyworld, a simplified ecosystem made up of only two elements, black daisies which absorb light and heat their environment, and white daisies that reflect light and cool their environment. At higher temperatures, black daisies suffer from the heat and are impaired until they eventually die. Similarly, white daisies cannot cope with low temperatures. With a heat and light input which starts weak then steadily becomes stronger, this planet tends towards an equilibrium temperature and the varying proportion of black to white daisies will maintaintain the planet at that equilibrium temperature. This is in contrast to a bare gray planet, whose temperature would steadily rise with the increased input of heat and light. The model remains valid even with many modifications (daisy-consuming rabbits; meteor strikes killing most of the daisies, "cheat" grey daisies which produce no pigment and have a higher rate of growth and reproduction) However, Lovelock intended Daisyworld as a starting point. It provides a model of how a Gaian system might work. It does not prove that the Earth functions as a Gaian system, and does not fully address the assertion that the emergence of a Gaian system is incompatible with current views on evolution. Gaia's advocates are engaged in asking "How do results from Daisyworld transfer to the real world?".
 Initial scientific criticism
Dr. W. Ford Doolittle is one of the most well-known critics of the Gaia hypothesis. In 1981, he wrote an article for CoEvolution Quarterly titled "Is Nature Motherly?" in which he conjectured that there is nothing in the genome of organic life which could provide the feedback mechanisms the Gaia hypothesis proposes, and that, therefore, the Gaia hypothesis was an unscientific theory without any explanatory mechanism, in violation of the scientific method. Richard Dawkins, in his book The Extended Phenotype, wrote in affirmation of Doolittle's critique of the hypothesis, arguing that organisms cannot act in a concerted effort, as it would require foresight and planning from them on a global scale.
Dr. James Kirchner criticized the hypothesis for i