November 20th, 2013

Gaia hypothesis

GAIA-1

The Gaia hypothesis also known as the Gaia theory or Gaia principle, proposes that organisms interact with their inorganic surroundings on earth to form a self regulating, complex system that contributes to maintaining the conditions for life on the planet. topics of interest include how the biosphere and the evolution of life forms affect the stability of global temperature, ocean salinity, oxygen in the atmosphere and other environmental variables that affect the habitability of earth.

The hypotheses was formulated by the scientist James Lovelock and co-developed by the microbiologist Lynn Margulis in the 1970′s. While early versions of the hypothesis were criticized for being theological and contradicting principles of natural selection, later refinements have resulted in ideas highlighted by the Gaia hypothesis being used in subjects such as geophysiology, earth system science, biogeochemistry, systems ecology, and climate science. In 2006, The Geological Society of London awarded Lovelock the Wollaston Medal largely for his work on the Gaia theory.

The Gaia theory posits that Earth is a self regulating complex system involving the biosphere, the atmosphere, the hydrospheres and the pedosphere, tightly coupled as an evolving system. The theory sustains that this system as a whole, called Gaia, seeks a physical and chemical environment optimal for contemporary life.

Gaia evolves through a cybernetic feedback system operated unconsciously by the biota, leading to broad stabilization of the conditions of habitability in a full homeostasis. Many processes in the Earth’s surface essential for the conditions of life depend on the interaction of living forms, especially microorganisms, with inorganic elements. These processes establish a global control system that regulates Earth’s surface temperature, atmosphere composition and ocean salinity, powered by the global thermodynamic disequilibrium state of the Earth system.

The existence os a planetary homeostasis influenced by living forms had been observed previously in the field of biogeochemistry, and it is being investigated also in other fields like Earth system science. the originality of the Gaia theory relies on the assessment that such homeostatic balance is actively pursued with the goal of keeping the optimal conditions of life, even when external events interfere with them.