THE idea that the earth’s physical and biological systems adjust to perturbation through feedback systems is central to James Lovelock’s Gaia theory. Let me declare upfront that I don’t subscribe to this theory because I don’t see the earth as a living entity, but rather as a place where life is lived. I do agree, however, that natural systems tend to exhibit strong negative feedback around an equilibrium point. Negative feedback is the opposite of positive feedback. It acts to oppose perturbation on a system and thus to maintain the current equilibrium. 
The Gaia theory is very popular including amongst many sceintists concerned about global warming notably Tim Flannery. Professor Flannery was named Australian of the Year in 2007 and is presently chairman of the Copenhagen Climate Council. The Gaia theory underpins his influential book on climate change ‘The Weather Makers’.
Given Professors Lovelock and Flannery believe in feedback systems which seek to maintain an optimal physical and chemical environment for life on earth, Gaia, it is perhaps surprising that they are so concerned about elevated concentrations of carbon dioxide causing a climate crisis.
I understand that this concern, as articulated by Professor Lovelock in his 2006 book ‘Revenge of Gaia’, stems in large part from a belief that Gaia has been so despoiled that the biological systems which would normally buffer, for example the capacity of phytoplankton and forests to draw excess carbon dioxide from the atmosphere, is no longer properly functioning.
But what if there exists a physical system, in addition to these biological systems, to prevent runaway greenhouse?
New research by Hungarian physicist Ferenc Miskolczi’s has shown that there will not be a runaway greenhouse effect because the atmosphere maintains a “saturated” greenhouse effect, controlled by water vapour content.  The analogy has been made to a saucepan of saturated salt solution boiling on a stove. Turn up the gas on the stove and the boiling point is not affected. Add more salt and the boiling-point is not affected, because the salt solution is already saturated. 
Dr Miskolczi’s work provides a detailed Gaia level empirical formulation of how the physical system works to maintain equilibrium. While American Climatologist Roy Spencer, has independently provided a nuts and bolts demonstration of possible mechanisms with respect to the hydrological cycle. 
So there is perhaps no longer a reason for Professor Lovelock to continue to believe that it is already too late to avoid significant global warming that will make much of the Earth’s surface inhospitable.
In summary, new findings by a Hungarian physicist and an American climatologist, interestingly both climate change sceptics, provide evidence for a physical system to support the popular Gaia theory of a world kept at an optimal equilibrium for life. 
And the really good news is that the critical regulating gas, water vapour, is unlikely to ever be limiting because there is just so much of it on planet earth. Indeed I think it is time James Lovelock wrote a new book and I suggest it be entitled, ‘Gaia: Saved by the Seas’.
Important Notes and Links
My ideas for this note come from correspondence with Christopher Game and have also been significantly influenced by reading Michael Hammer. But I don’t expect them to agree with much of what I have written.
1. Michael Hammer recently commented at this blog that “Natural systems virtually all exhibit strong negative feedback around an equilibrium point.” Mr Hammer made the comment to contrast this observation with the IPCC temperature rise claims which are based on an assumption of strong net positive feedback in our climate system. Negative feedback is the opposite of positive feedback. It acts to oppose any disturbance acting on a system and seeks to maintain the current equilibrium.
2. F.M. Miskolczi (2007) Greenhouse effect in semi-transparent atmospheres, Quarterly Journal of the Hungarian Meteorological Society 111(1): 1-40.
‘The Saturated Greenhouse Effect’ by Ken Gregory provides a good summary of the new theory developed by Ferenc Miskolczi .
3. Christopher Game would add that the climate process is different from a boiling saucepan in one important respect. Non-equilibrium phase transitions are a little conceptually different from equilibrium ones. The phase transition at which the climate process is pinned is dynamical in character, in contrast with the phase transition of boiling water which has a static character. Consequently the physical quantity that is pinned is not the climate temperature; it is the climatic response ratio.
4. Roy Spencer and Danny Braswell, Potential Biases in Feedback Diagnosis from Observational Data: A simple Model Demonstration, Journal of Climate.
Roy Spencer, recently commented at his blog that:
But the climate system tinkers with itself all the time, and the climate has managed to remain stable. There are indeed internal, chaotic fluctuations in the climate system that might appear to be random, but their effect on the whole climate system are constrained to operate within a certain range. If the climate system really was that sensitive, it would have forced itself into oblivion long ago.
Testimony of Roy W. Spencer Before the US Senate EPW Committee: Latest Research on Climate Sensitivity to CO2
5. It is not generally acknowledged, including by either Roy Spencer or Ferenc Miskolczi, that their important work fits neatly together or supports the Gaia theory, this is my opinion.
I have relied to a large extent on a series on ABC radio two summers ago and Wikipedia for my understanding of Gaia as described by James Lovelock. I have not read any of James Lovelock’s books. I am more familiar with the work of Tim Flannery and have read the ‘Weather Makers’. http://en.wikipedia.org/wiki/Gaia_hypothesis