It appears James Lovelock in his book, The Revenge of Gaia , gives an outlook Hanrahan would approve of . Lovelock is loved by the media for his apocalyptic and doomsday language as well as his controversial views such as converting to nuclear power and creating man-made viridians to deal with the waste. Is is a shame that this is how Lovelock chooses to package his views to the media, Daisyworld is a very interesting model.

Lovelock writes in a heavy doomsday language with an emotive and humanistic description of the earth's climate;

Our planet has kept itself healthy and fit for life, just like an animal does, for most of the more than three billion years of its existence. It was ill luck that we started polluting at a time when the sun is too hot for comfort. We have given Gaia a fever and soon her condition will worsen to a state like a coma. She has been there before and recovered, but it took more than 100,000 years. ...

We are in a fool's climate, accidentally kept cool by smoke, and before this century is over billions of us will die and the few breeding pairs of people that survive will be in the Arctic where the climate remains tolerable.

This type of language makes him easy to dismiss as a crank or a weirdo. Which is unfortunate as his hypothesis and models may have value in future terraforming operations of currently uninhabitable planets. Mars being the most obvious candidate and one which he focuses on heavily in his writings.

I think Gaia is an unfortunate name for his hypothesis, if it had been called the complex-dynamical-equilibria theory it might have been less easy to dismiss as a hippy holistic view of the world.

Essentially his theory is that the complex system we know as the climate and ecosystem of earth acts to self-dampen when faced with external inputs. It does this far beyond its ability to maintain that equilibrium, at which point it flies out of control as a system, until it is able to realign itself to a new state and equilibrium.

Stripped of the emotion, sensationalist language and new age feeling it is not an earth shattering statement. For technologists such as statistical process control engineers, climatologists, geologists, transport engineers, software developers, economists and stock traders it is a description of complex system behaviour that they see constantly.

He came to these conclusion while running Daisyworld models for insight into the question of whether Mars contained life on it. Lovelock put three species of daisy on a theoretical world, with Terran style growth rates, and then modified the external input of heat from the nearby sun. His results were that in higher temperatures the light daisies to over the population as their colour enabled them to deflect the heat better than black daisies, at lower temperatures the opposite occurred. Ultimately it made an environment where all the daisies could exist, though not in equal populations.

The other insight from this model was that the variation in daisy species enabled the system to self-dampen even with a strong external input - excess energy - being constantly added to the system. This fell down however, once the daisies were unable to dampen the external input any further, and a catastrophic re-alignment occurred. On the lower graph this is displayed at 1.2 luminosity.

Another of his findings from this model was that diversity of species was greatest when the system was self-dampening. As it went through catastrophic re-alignments or went out of control, the species numbers dropped to one. This meant that even if the system did gain some semblance of control it would not be able to self-dampen if the external input that caused the stress was removed.

Lovelock continued his experiments with the Daisyworld model by mimicking aspects of the 1920s Fox vs Rabbit experiments of Lotka and Volterra . He introduced plagues into his model which killed off 30% of the daisies. In the self-dampening area, this was quickly recovered from with just two quick pulse disturbances in populations.

Unfortunately in the media we don't see this kind of analysis of Lovelock's work. Worse, Lovelock exacerbates the problem by his doomsday rhetoric.

The Gaia hypothesis is a catastrophic model, once the point is reached that goes out of control, it means the system has dampened itself beyond recovery. This is in contrast to climate models which increase incrementally with slow die off of species with increasing heat inputs.

The analogy of those incremental models is like boiling a frog slowly. The frog doesn't really notice despite the changes having a long linear history. Under the Daisyworld scenario, the change is drastic, catastrophic and will result in massive fluctuations in diversity and environment over a short period.

Without the Hanrahan warnings and new age romanticism, the basis of Lovelock's theory has merit and is pause for thought and further study. I wish it wasn't so polluted by language; Lovelock and the media can share blame here.

Anyway, here is a flash animation visually describing Daisyworld, while here are two Daisyworld simulators in 2D and 3D .

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