Nostradamus

Original the Daisyworld model

This model is a simplified digital representation of a Planet like the Ground but without ocean, whose Climat stabilizes by the effect of the competition whatever the incidental Rayonnement, and who orbits like the Earth around a star similar to the Sun. This planet rotates and contains relatively few Nuage S and Gaz to greenhouse effect in its atmosphere, which would complicate its climate. On this planet the average temperature is only determined by its reflective capacity (albedo) and can be thus calculated by the Loi of Stefan-Boltzmann.

The biology of Daisyworld is also very simple. Gaïa is covered with daisies which start to germinate as soon as the temperature reached 5°C and cease growing above 40°C; they present an optimal growth to a temperature of 20°C.

The biosphere of Daisyworld contains only clear daisies (white) and dark daisies (black or coloured). These flowers influence only the temperature of surface through their reflective capacity.

As in nature the dark daisies absorb the most heat; the clear daisies reflect the essence of the radiation in space. But how the radiation reflected by the individual daisies can affect the total temperature?

As the star becomes more luminous, the average temperature on the surface of Gaïa increases. One can thus predict the evolution of the population of the daisies as the planet is heated.

This model applying the traditional laws of biology and physics, in the terrestrial environment " normal" the daisies can answer or to adapt to the physical environment but cannot modify it. On the other hand on Daisyworld the daisies can deteriorate the climate.

How does the Rétroaction function, process key of this study? The variable of the system is controlled by two effects which act as direction opposed on this variable while being inhibited reciprocally. On Daisyworld, the variable is the Température. The warming or cooling is caused by the dark or clear daisies which are eliminated mutually to conquer space.

Concretely, when the temperature reached 5°C, all the seeds germinate. During the first season, the dark daisies grow at intervals faster than their clear cousins because they absorb more light. Invading all the space of Daisyworld, its surface and the atmosphere in contact with this one are heated - as any surface exposed to the Sun -. The component sinks will be thus the species best adapted and it locally creates hot zones which support the growth of the other daisies.

At the end of the first season, there are on Daisyworld much more dark daisies than the clear ones. The first thus dominate the landscape when the springtide arrives. They grow, are heated like their biotope. This dark explosion of daisies creates a positive Rétroaction resulting in ' increasing the temperature of Gaïa quickly. Soon the planet contains nothing any more but dark daisies, their cumulated effect increasing the total temperature above the value measured in the absence of all Vie.

Progressively of the global warming, the white daisies end up also developing, by benefitting from these best climatic conditions, until the planet reaches a temperature of balance.

What does it occur for a higher temperature? The white daisies will not be able to maintain the temperature sufficiently high to survive. The temperature cannot increase indefinitely, with the risk to overheat the atmosphere by limiting the growth of the flowers. Even the radiation of the Sun cannot exceed the maximum tolerance supported by the daisies. As the planet ages, the heat of the Sun becomes so high that the dark daisies end up dying. Arrived at this stage, only survive the white daisies which always manage to stabilize the temperature in the neighborhoods of 20°C.

Under these conditions of extreme sunning, only the clear competitors will be favoured, but because of their capacity to reflect the sunlight, they will cool also quickly just as the low layers of the atmosphere. As the white daisies colonize Daisyworld, their cumulated effect will cause well a fall of the total temperature in lower part of the value measured in the absence of any life.

On the basis of this experiment one can conclude from it that the competition which settles between the various species of daisies will carry the average temperature of surface of Gaïa close to the values offering a maximum of comfort. In this manner, the individuals, without being aware nor to be concerned by becoming to it of Daisyworld taken in its globality, will have managed to control the total environment of their planet.

If one takes account of the changes in our model, by modifying for example the albedo during the growth of the flowers, one notes that one can increase the solar radiation by at least 20% before the populations do not crumble. Finally, the heat emitted by the Sun will be so intense that more no species of daisy will be able to control the temperature and all the species will disappear.

With final, when simulation is launched in the absence of daisy, the change of the planetary temperature is function of the Solar radiation. In the presence of daisies, one observes a warming at the beginning of simulation and a cooling at the end of the simulation, resulting in a thermal balance during the essence of simulation. Thus, the daisies modify the Climat in order to return it to them hospital.

The continuation of the model

At the time where Lovelock created its Daisyworld model with only one dimension, he was unaware of the Biologie of the populations and the fact that if this type of model contained more than two species in simultaneous competition, the system was almost invariably unstable.

This problem will be solved by introducing a space dependence into the model. The local temperatures T1, T2 and the Albedo S.A. 1, A2 can be replaced by fields with two dimensions T (X, there) and has (X, there).

In this manner the temporal and space evolution of the temperature is determined by partial differential equations based on an energy model of balance, the evolution of the albedo directly being connected to the vegetation and being modelled by the approach of the cellular automaton. Thus this model Bi or three-dimensional can apply to quantity of problems, of the calcite formation in the microbial marshes with the fragmentation of the habitat S.

Lovelock worked out then a new model containing between 3 and 20 species of daisies of different colors living in Compétition to conquer the space of their planet, controlling their world unconsciously as they had done up to now. These data-processing models include/understand gray daisies whose color is identical to that of the stripped surface of the planet host. The model with 10 flowers for example, is as stable as the model containing two species of flowers but it offers the advantage of being able to control the temperature with more precision.

Interests of these models

By incorporating the physical environment in this model, a variable that the theorists in ecology had never used until now, the inherent instability which brought out from the ecological models multi-species disappears. Consequently one could add rabbits or other herbivores to cut the daisies and even of the foxes, to kill rabbits, without testing the Stabilité system.

Thus in a way much more independent than in the first version, Lovelock finds for the first time a theoretical justification with the Biodiversité by the means of the influence of the number of species on quality of the stabilizing effects obtained on the unit of the Planet. Diversity is vastest when the temperature control is most effective, and lowest when the system undergoes a stress: at the moment when the growth begins or when the daisies suffer from heat and decay. This discovery supports the idea of the essential character of the maintenance of the Biodiversité and started again the Débat on the biodiversity on this subject.

These multidimensional models show some remarkable effects:

the local interactions between the species in competition lead to total effects: under disturbances external a temperature regulator behavior total car-is organized;
the system undergoes a transition from phase of first order: when the maintained mode is stressed, an irreversible crack occurs immediately;
By parcelling out the areas (for example by splitting up the regulating behaviors) the mode also breaks.

Of course Daisyworld or its alternatives is a model and not a receipt to put a planet under air conditioning! But it is about a general model which is not limited to the daisies and the climate. Since its first experiment in 1982, Lovelock created models sticking to the primitive times of the Earth, the Archéen and the Protérozoïque of the Précambrien, by programming micro-organisms able simultaneously to control the composition of the atmosphere and the climate.

Daisyworld provides a powerful tool which offers a plausible explanation in the way in which Gaïa functions and the reasons for which any predestination or planning is useless to balance the biosphere. But some share the explanation remains virtual, sticking to a simplistic world, simply connected and not being subject to the anthropogenic influence (human colonization and its inevitable infrastructures) which always ends up parcelling out the landscape in various concentrations of species or unfertile zones.

See too

Theories Gaia
Assumption Gaia
Feedback

External bond

Daisyworld on the site '' Luxorion ''

Random links:

3M | Station at the Four Villages | Origins of agriculture | Thalion | Tokyo Mid-Town Tower