Neolithic revolution: from gathering to producing
Mongols' defeats and „Black Death' in Europe
Beginning of industrial revolution
Fig. 11.1. Energy food demand for mankind, 1 GJ = 109 J. From Svirezhev and Svirejeva-Hopkins (1998) with changes.
numbers one can say that Homo sapiens as a biological species was very fortunate that it had not been eliminated before the technosphere arose.
The NPP of the biosphere, 2.3 X 1021 J/year, is the energy flow, which maintains the diversity of biota. Even now, the energy flow used by the technosphere, 3 X 1019 J/year, is only about 13% of the biosphere NPP. At the present moment, the biosphere and technosphere are in a state of strong competition for common resources, such as land area and fresh water. Contamination of the environment and reduction of the biota diversity are the consequences of the competition.
Since the biosphere (considered as an open thermodynamic system) is at the dynamic equilibrium, then all entropy flows have to be balanced too. Therefore, the entropy excess, which is created by the technosphere, has to be compensated by means of two processes: (1) degradation of the biosphere, and (2) change in the work of Earth's climate machine (in particular, the increase of Earth's average temperature).
Let us assume that all energy consumed by the technosphere is transformed into heat Q. Then the annual entropy produced by the technosphere is equal to Stech = Q/T = 3 X 1020 J/287 K year < 1018 J/K year at the mean annual temperature of Earth equal to 14°C. The full destruction of biota, which, we assume, is equivalent to its full combustion, gives us the following value of entropy: Sd = 3.5 X 1022 J/287 K < 1.21020 J/K. If we assume that the energy consumption of the technosphere would not be increased, then this "anti-entropy storage" of biota would be enough to compensate the entropy produced by the technosphere in the course of the next 120 years. If this techno-generic entropy would be compensated by soil destruction then the agony would be continued in the course of 300-400 years, since the organic matter storage in soil is 3-4 times larger than in biota.
Let us talk about the concept of sustainability. Despite its widespread use, there is no rigorous, mathematically correct definition of sustainability. (Note, the same situation exists with the term "stability" except there is a mathematical theory of stability with the rigorous Lyapunov definition, but the "sustainability" concept was still not formalised).
As a result of the Brundtland Commission book "Our common Future. From one Earth to one World" (Oxford University Press, Oxford-New York, 1987), the concept of sustainability is well known today. Nevertheless, it is necessary to note that the concept has a longer time history. Let us recall that V. Vernadsky has introduced a new global system called "Noosphere", which has to be a final stage of the co-evolution of the biosphere and human technological civilisation. Unfortunately, this very attractive idea of sustainable development runs counter to the basic laws of physics (the Second Law of Thermodynamics). What arguments can be used to prove this last thesis (see also Svirezhev and Svirejeva-Hopkins, 1998)?
Let us consider the entropy balance of a single area of the Earth's surface occupied by some natural ecosystem (for details see Chapter 10). At the dynamic equilibrium the entropy production within the system is balanced with the entropy flow from the system to the environment. This work is done by the "entropy pump".
Suppose that the considered area is influenced by anthropogenic pressure represented by the direct inflows of artificial energy (energy load) and the inflows of chemical substances (chemical load). This is a typical impact of industry (or, in a broader sense, technological civilisation) on the environment.
If we consider the main characteristic features of technological civilisation, we can see that it creates the energy and chemical loads. These features are:
(a) the use of the non-biosphere sources of energy (fossil fuels, which are the traces of past biospheres, not replenishable by the current biosphere, and nuclear energy);
(b) technological processes increase concentrations of chemical elements in the biosphere (metallurgy, chemical industry, etc.);
(c) dispersion of chemical elements in comparison with their "biotic" concentrations.
All these above-mentioned processes produce entropy that cannot be "sucked" out by the biosphere's "entropy pump". But since the ecosystem should remain in a dynamic equilibrium with its environment, the entropy production (overproduction) of the ecosystem should be compensated by the outflow of entropy to the environment. This compensation can occur only at the expense of environmental degradation in this or, maybe, another location, heat and chemical pollution or caused by mechanical impact on the system. The value of the overproduction (as was shown in Chapter 10) can be used as a criterion for the environmental degradation or as an "entropy fee", which has to be paid by society (really suffering from the degradation of environment) for the modern industrial technologies. Thus, degradation of the environment is the only way to compensate for the overproduction of entropy. The process of overproduction can be non-homogenous in space and then there is the spatial transportation of entropy. This transportation can be either natural or artificial. The natural process of entropy transportation is realised as the wide spreading of different pollutants by natural agents (wind, rivers, etc.). The artificial process is either a purposeful export of industrial waste to other regions, or the import of low-entropy matters (for example, fossil fuels) from other regions. So, the main conclusion is:
Sustainable development is possible only locally, and only at the expense of creating "entropy dumps" elsewhere.
11.4. Thermodynamics model of the biosphere. 1. Entropy balance
From the point of view of thermodynamics, our planet (Earth, E) is a closed system, which exchanges with its environment (Space, S) only energy. Let us assume that the total mass of Earth's matter is not changing in the course of the considered time interval. Therefore, we can neglect the "slow" input and output flows within "geological" characteristic time and consider only the solar radiation and Earth's heat irradiation as a unique type of exchange between Earth's system and its environment. Moreover, we assume that the planetary radiation balance is also constant. As such a kind of interval we can assume 103 years.
Let diSE be the annual production of entropy by Earth and de SE be the annual export of entropy into Space. If the joint system "Earth + Space" is in a dynamic equilibrium, then diSE = — deSE, where dESE < 3.6 X 1024 J/year is the annual solar energy assimilated by Earth, TS = 5770 K and Te = 257 K are radiation temperatures of the Sun and Earth, and the factor 4/3 is the Planck form-factor (Ebeling et al., 1990).
Assume that our system (Earth) can be represented as a sum of the following subsystems: atmosphere (A), biota (B), pedosphere (P), hydrosphere (H) and lithosphere (L). Note that the mass of biota can be identified with Earth's phytomass; only water (or salt dilutions) is included into the hydrosphere, polar ices and glaciers are included in the lithosphere, which, in turn, contains Earth's core, mantle and kernel. Each of these subsystems exchanges with each other and with Space by energy and matter. In particular, the matter exchange is realised by means of the global biogeochemical cycles. There is no exchange between biota and lithosphere.
Let diSj $ 0 be the entropy production by jth (j = A, B, P, H, L) subsystem, dSjk the export of entropy from jth subsystem to kth one, dSSk the export of entropy from Space (environment) to kth subsystem. By writing the equations of entropy balance for all the subsystems, then summarising them and taking into account that dSjk = —dSkj for any
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