by Whit Gibbons

January 31, 2010

I have encountered the word "Gaia" twice in the last month.

The first time was in a series of questions someone asked following another week of stormy weather. "Is El Niño telling us something more than that the western Pacific Ocean waters are warmer than in the past few years? Is El Niño confirming the Gaia hypothesis? Is it a response to global warming?" The weather questions were related to last summer's announcement by the National Oceanic and Atmospheric Administration that the climate phenomenon known as El Niño, a warming of the Pacific Ocean that causes widespread changes in the weather, would be making an appearance in 2009 and probably remain through the winter of 2009-2010.

The second time was when I told a friend of that discussion and she said, "Gaia supporters have the 'granola mentality'; they think Nature and Mother Earth will keep the planet healthy."

Who or what is Gaia, and how might a weather phenomenon confirm the Gaia hypothesis? In Greek mythology, the goddess Gaia was indeed Mother Earth. The modern references to Gaia are based in that concept, with Earth itself being considered a superorganism that responds to changes that affect it.

The idea of Earth, or Gaia, as a self-regulating superorganism was formulated three decades ago by J. E. Lovelock in a book titled "Gaia: A New Look at Life on Earth." The concept, which had its roots with the early Greeks, has persisted and is now a doctrine of some environmentalists, as well as some respected scientists. Many scientists, however, dispute the idea.

The Gaia hypothesis, or "theory" as its advocates now call it, proposes that the physical and chemical conditions on Earth, including those of the atmosphere, oceans, and land masses, are held in equilibrium by the living inhabitants of the planet, which means all life, not just humans. In contrast to the generally held assumption that life on Earth has adapted and adjusted through evolution to environmental conditions on the planet, the Gaia concept presents a world in which life itself maintains the worldwide environmental balance.

An example is the salinity level in the ocean, where salts are constantly added by physical and chemical processes. According to Lovelock, seas left strictly to physical and chemical forces would eventually reach an unlivable state. The Gaia hypothesis proposes that, since the beginning of life on Earth 3.5 billion years ago, ocean salinity has been under biological control (in contrast to strictly physical or chemical mechanisms) through a cooperative action of ocean organisms. That is, living creatures in the sea, primarily algae and protozoa, have served a salt-removal role, maintaining the oceans in a state that can support life.

Salt can be removed from ocean waters by deposition on the bottom. A proposed mechanism is the constant shower of dead micro-organisms falling to the ocean floor. As salinity levels begin to rise, plankton incorporate salt into their outer coverings. When they die and sink to the ocean depths, they remove the increased salt load.

The Gaia concept gives comparable explanations for the maintenance of atmospheric gasses in proportions necessary to sustain life. Without the constant biological creation of oxygen and methane, for example, the air most animals breathe would be profoundly altered. According to the Gaia hypothesis, the organisms of the world work together to sustain an atmosphere that supports life.

The concept of the earth itself and its inhabitants sustaining environmental equilibrium is a contentious issue among many nonscientists. Oddly enough, opponents approach the issue from two different points of view but from the same starting point: the Gaia hypothesis does not place human beings in a central role. Some opponents perceive Gaia advocates as people who place the welfare of other organisms on the same level as, or even above, humankind. Others object because the Gaia hypothesis might offer an excuse for behaving in an environmentally irresponsible manner.

Within the Gaia framework humans are simply one species among millions, with no special rights. The presence of humans would make little difference to the survival of Gaia. If we disappeared, the equilibrium would continue.

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