In our first publication [1] we formulated the following questions:
In this publication we continue to answer these questions, considering the system ''biosphere + climate'' as a system with very strong non-linearities and multiple equilibria. Note that we remain within a framework of the simplest zero-dimensional models. The results obtained by the analysis do not depend on the explicit form of the chosen functions and can be generalized to a system obeying the same topological structure.
It is obvious that vegetation dynamics depend on temperature, precipitation, and the concentration of carbon in the atmosphere. On the other hand, temperature dynamics depend on the concentrations of carbon and water vapour in the atmosphere, and on the albedo of planetary surface. For instance, the albedo of ``white sands'' desert is equal to 0.4; for coniferous forest it is about 0.1 [2]. Our model includes the following simple submodels: global carbon cycle, vegetation and the equation for annual global temperature.
A few words about the history of this problem. Kostitzin[4] realized Vernadsky's[5] idea about an interdependence between vegetation and climate in the form of a mathematical model for the coevolution of the atmosphere (climate) and the biota. It is interesting that this was the first mathematical model of a global carbon cycle. His ``epoques glaciaires'' act as self-oscillations of this system. Further attempts at the modelling of climate-vegetation interactions were made by Watson and Lovelock[6] (``Daisyworld'' a model of a hypothetical planet). In 1994 Svirezhev[7] formulated the so-called ``virtual biospheres'' concept. According to this, the contemporary Earth Biosphere is one of many possible (virtual) biospheres, corresponding to multiple equilibria of some strongly nonlinear dynamic system ``climate + biosphere''
In the course of our planet's history and own evolution this system passed through several bifurcation points, when random factors (small perturbations) determined which branch of the solution the system would take. A moving force of this evolution could be the evolution of the ``Earth green cover'' which has, in turn, several bifurcation points, e.g., the appearance of terrestrial vegetation and the change from coniferous to deciduous forest.
Note that this concept contradicts Vernadsky's ``ergodicity axiom'' according to which the contemporary Earth Biosphere is unique, beyond dependence on its initial and previous states.