Gaia Theory

[Aura]

Ever heard of this theory? Basically it states that all organic and inorganic materials on Earth are closely integrated to help mantain the conditions to sustain life, namely the stability of global temperature, ocean salinity, oxygen in the atmosphere and other factors of a preferred homeostasis.

Ocean salinity has been constant at about 3.4% for a very long time. This was a mystery, because river salts should have raised the ocean salinity much higher than observed. Recently, it was suggested that salinity may also be strongly influenced by seawater circulation through hot basaltic rocks, and emerging as hot water vents on mid-ocean ridges. Still, the composition of seawater is far from equilibrium, and it is difficult to explain this fact without the influence of organic processes.
Atmospheric composition remains fairly constant, providing the ideal conditions for life. All the atmospheric gases other than noble gases present in the atmosphere are either made by organisms or processed by them. The Gaia theory states that the Earth's atmospheric composition is kept at a dynamically steady state by the presence of life. The stability of the atmosphere in Earth is not because of chemical equillibrium. Oxygen is the second most reactive element after fluorine, and it should combine with gases and minerals of the Earth's atmosphere and crust. Traces of methane should not exist, as methane is combustible in an oxygen atmosphere.
Since life started on Earth, the energy provided by the Sun has increased by 25% to 30%. However, the surface temperature of the planet has remained within the levels of habitability, reaching quite regular low and high margins. The CLAW hypothesis, inspired by the Gaia theory, proposes a feedback loop that operates between ocean ecosystems and the Earth's climate.The hypothesis specifically proposes that particular phytoplankton that produce dimethyl sulfide are responsive to variations in climate forcing, and that these responses lead to a negative feedback loop that acts to stabilise the temperature of the Earth's atmosphere. Currently, this Gaian homeostatic balance is being pushed by the increase of human population and the impact of their activities to the environment. The multiplication of greenhouse gases may cause a turn of Gaia's negative feedbacks into homeostatic positive feedback. According to Lovelock (the man who formulated this theory), this could bring an accelerated global warming and mass human mortality.

http://en.wikipedia.org/wiki/Gaia_hypoth...the_oceans

So what do you think? I think it sounds pretty cool.

[Autumnlicious]

It is conceptually ridiculous to think that the maintenance for life is a requirement/modus operandi for the Earth. It isn't.

Mars is evidence enough for the road not taken.

The Great Oxygenation Event was devastating to existing life back then -- in fact, it would seem to certainly be the end of the world for a great many anaerobes.

The Earth, like any other celestial object, simply is.

In addition, the timescale for the deep ocean to respond to atmospheric forcing is on the order from decades to millennia -- we don't understand why the time scale is so loose, only that we can predict certain events due to knowledge of the thermocline and rough saline distribution.

Abiogenesis and panspermia (what I can think of off the top of my head) would most likely be responsible for life forming under a set of initial conditions -- whether life adapts "fast" enough is left purely to the success and failure of any set grouping of life forms. Past that, there is little to state about a planet and it's ability to "support life". Recent papers by Dr. Christopher McKay et al have indicated that the possibility for life existing on Mars during certain timeframes is quite real -- yet no one would argue seriously that Mars is hospitable to "life as we know it" (perhaps though for life as we don't know it )

In short, life does have a noticeable effect on this planet. However, it doesn't maintain any form of homeostasis by intention.

The Great Oxygenation Event is a wonderful example of such.

[The Magic Pudding]

In short, life does have a noticeable effect on this planet. However, it doesn't maintain any form of homeostasis by intention.

I don't know who suggests intention, not unless we are talking about a future wiser more able us.
I don't think Gaia should be disregarded because of adoption and distortion by the new age flower in hair types.

Tim Flannery talks about Gaya here. http://www.abc.net.au/rn/scienceshow/sto...101365.htm

[Autumnlicious]

Gaea Theory presupposes that the interaction between life and inorganic components of the Earth perpetuate the capability for carrying life on the latter.

While it may be true that there are inorganic feedback systems that kill off groups of organisms after the system is perturbed past a certain point, that would be the extent.

I cite the Great Oxygenation Event as an example of life, at one point, causing drastic changes to the planet on which it resided. I see little to keep such from occurring again -- a new species of life might very well, through it's very existence and processes, destroy what we consider "habitable".

To me, Gaea seems a fanciful elaborate construct pasted over natural processes that we already know of -- like niches, evolution and adaptation.

[Aura]

I apologize... I'll be away until Friday/Saturday, but I'll reply to these posts as soon as I am able to.

[Anomalocaris]

It is conceptually ridiculous to think that the maintenance for life is a requirement/modus operandi for the Earth. It isn't.

Mars is evidence enough for the road not taken.

The Great Oxygenation Event was devastating to existing life back then -- in fact, it would seem to certainly be the end of the world for a great many anaerobes.

The Earth, like any other celestial object, simply is.

In addition, the timescale for the deep ocean to respond to atmospheric forcing is on the order from decades to millennia -- we don't understand why the time scale is so loose, only that we can predict certain events due to knowledge of the thermocline and rough saline distribution.

Abiogenesis and panspermia (what I can think of off the top of my head) would most likely be responsible for life forming under a set of initial conditions -- whether life adapts "fast" enough is left purely to the success and failure of any set grouping of life forms. Past that, there is little to state about a planet and it's ability to "support life". Recent papers by Dr. Christopher McKay et al have indicated that the possibility for life existing on Mars during certain timeframes is quite real -- yet no one would argue seriously that Mars is hospitable to "life as we know it" (perhaps though for life as we don't know it )

In short, life does have a noticeable effect on this planet. However, it doesn't maintain any form of homeostasis by intention.

The Great Oxygenation Event is a wonderful example of such.

I am afraid I disagree with both your interpretation of what the Gaia hypothesis is, and your opinion of what it says.

1. Gaia hypothesis is not some spiritualist mumbo jumbo assigning intention and purpose to natural systems despite how new age air heads would like to interpret it. In fact its core is so constructed as to be susceptible to scientific inquiry. It postulate mechanisms which are susceptible to observation, and makes prediction which are susceptible to verification. One might argue whether it was the most parsimonious hypothesis that can be imagined that seeks to explain what it initially sought to explain, but it is at least capable of being in the running as model of how the biosphere had worked.

2. The fact that other potential biospheres had appeared to fail does not require a special exemption under the Gaia hypothesis. In fact Gaia hypothesis, if worked out in detail, would predict that the same fate would before the earth as the biofeedback mechanism will unavoidably fail when the moderating agent of CO2 in the atmosphere will eventually be exhausted as it is sequestered by the biosphere to compensate for ever warming sun, and the biosphere would then irremediably collapse, and the ocean will evaporate, it's water dissociate, carbon sequestration then reverse, and the earth become like Venus.