Arthur Jones, "The optimum environment for living things" (1997)

The optimum environment for living things

 The design of our planet Earth is infinitely more remarkable than most people realise. The atmosphere, soil, seawater and Earth's crust should all decompose, becoming a hot, hostile atmosphere like Venus and with toxic saturated salt seas, unable to support life. However, this is not the case! This article describes how the extraordinary composition of the Earth is maintained; how all of the Earth's domains and elements are needed for this; indeed how the whole solar system is integral to supporting life on Earth; and of how this relates to God's laws, which all relate harmoniously. To ignore or disobey these laws in one area brings repercussions in many other areas. Thus economic greed is having serious economic and ecological effects. 

The universe consists almost entirely (99.9%) of incandescent gases, and these gases consist almost entirely of hydrogen and helium. The other 0.1% of the universe consists of frozen solids (e.g. planets, comets) drifting in space. The liquid state is so very rare that its relative occurrence is immeasurably small. What a contrast on Earth! Earth domains accessible to investigation consist almost entirely of oxygen and oxygen compounds, especially water. The Earth's average temperature is a warm 15ºC, so we find vast amounts of liquid water. 

Under these conditions at the Earth's surface, three kinds of interactions dominate all chemical activity: precipitation, acid- base and redox reactions. 

1. Precipitation reactions (no transfer of particles) > <i>e.g.<i> NaCl(aq) + AgNO3(aq) --> NaNO3(aq)+ AgCl(s) 2. Acid-base reactions (proton transfer reactions) > <i>e.g.<i> HCl(aq) + NaOH(aq) --> NaCl(aq)+ H2O(l) 3. Oxidation-reduction (redox) reactions (electron transfer) > <i>e.g.<i> Zn(s) + Cu(NO3)2 (aq) --> Zn(NO3)2 (aq) + Cu(s)

> &nbsp; <p>The Earth's abundance of water and oxygen compounds (especially CO<sub>2<sub>and carbonates, silicates and borates) ensures that acid-base and redox conditions on Earth are rarely extreme. Under normal conditions, redox reactions cannot exceed the point where oxygen or hydrogen would be liberated by the decomposition of water. On a world scale, acid-base reactions are buffered by rock carbonate, atmospheric CO₂ and rock silica/silicates, so that natural pHs rarely go outside the range pH 4 - pH 9. 

The elements

The natural roles of the elements are largely ignored, particularly in school science, yet a simple understanding of them is essential to an appreciation of the wonderful structure of God's world. A few examples will give the flavour of this approach. 

1. Hydrogen is the key element for the universe at large, able to release more energy in its reactions (especially nuclear fission) than any other element. It has many other roles. For instance, its physical bond (the "zip fastener" hydrogen bond which can be made or unmade with little change of energy) is vitally important to the functioning of water and of key organic compounds such as proteins and nucleic acids. 

2. Oxygen is the key element for making an inhabitable planet, especially because it reacts with hydrogen to form water and with silicon to form silica and silicates. In its readiness to accept electrons, oxygen is also at the centre of the redox reactions on which life depends. 

3. Silicon is the key element of the solid Earth, i.e.rocks. The silicon-oxygen bond is so strong that hard and stable silicon-oxygen minerals are abundant (95% by mass of the Earth's crust). Silica rocks slowly weather to give the chemically-inert (unreactive) sand/silt fraction of soils. This soil skeleton is essential to ensure proper soil texture, porosity (aeration, drainage), capillarity, water-holding capacity, fertility, plant-root penetrability, etc. All good (fertile) soils contain at least 75% sand/silt. 

4. Aluminium is the key element in soils. Its presence in silicate rocks promotes one of their main functions: to act as a reservoir of important elements (i.e. plant nutrients) which weathering processes release into the soil. When aluminium silicates are weathered practically none of the aluminium is lost by solution, and so the resulting clayshave relatively much more aluminium. Clay (in combination with humus) holds plant nutrients against leaching by rain, yet loosely enough for them to be absorbed by plant roots. 

5. Nitrogen. Its relatively unreactive molecules are essential to build up air pressure and to dilute oxygen. The proportions of these gases are quite critical. With less than 14% oxygen, no fire could be lit, whereas at 22% oxygen forest fires would occur too easily, and at 25% oxygen even wet vegetation would burn and lightning would quickly destroy the biosphere. 

6. Sodium, Potassium and Chlorine are extremely reactive elements, but form very stable compounds. Their ions (Na⁺, K⁺, Cl^-) play essential roles in the Earth's fluids, both inorganic (i.e. oceans, seas) and organic (i.e. body fluids, blood). These ions do not react or precipitate with any other common substances and so are vitally important for maintaining fluid concentrations and osmotic balance. 

7. Calcium and Magnesium are key elements for skeleton formation, providing some easily soluble compounds (i.e. hydrogen carbonates, chlorides, nitrates) - so the elements are readily available and can be transported in rivers and body fluids - and some hard insoluble solids (i.e. carbonate, phosphate) so that hard parts such as shells, bones and teeth can be built up. Their ions, having a double positive charge, are also important for linking or cementing other substances, again in both inorganic (i.e. cementing sediments) and organic realms (i.e.cell walls, blood clotting, precipitation of milk protein in the stomach). 

8. Sulphur and Phosphorus are the key elements in energy transfer processes. In organisms they are especially prominent as links (i.e.ATP) between the fundamental redox reactions and cellular activities. Divalent sulphur has long bond radii and so readily cross-links other substances (i.e. sulphur bridges in the keratin proteins of hair, horns and nails). 

The solar system

It has become increasingly clear that the size and complexity of the solar system is essential for life on Earth. The gravitational pull of the giant planets, especially the very massive Jupiter, protects the smaller planets such as the Earth from frequent collisions with comets and asteroids. 

The orbits of all the planets are chaotic (i.e. unpredictable in the long term). Nevertheless, against all expectations, the whole system remains very stable indeed! Similarly, Earth's large Moon prevents gravitational tugs from other planets destabilising the Earth's angle of tilt (which creates the regular pattern of seasons). Without the Moon, the tilt would be unpredictable leading to highly erratic variations in climate, as does happen on Mars. 

An improbable world

The Earth is composed of a number of physical domains (e.g. the Earth's crust, the atmosphere, soil and seawater). The most remarkable thing about the composition of these domains is that most of them are physically and chemically unlikely! Consider the atmosphere domain, a mixture mainly of the very reactive gases nitrogen and oxygen. Under Earth conditions, their overwhelming tendency is not to stay free (uncombined) as the gaseous elements, but to combine with (or oxidise) other elements until they attain their most stable forms - oxides and nitrates. The relative stability of their two-atom molecules (O₂, N₂) unfortunately masks their high reactivity and gives a quite misleading impression. Under the Earth's warm, moist conditions, oxygen should steadily disappear from the air as it oxidises, for example, reduced iron (Iron II, ferrous iron) to rust (Iron III, Ferric iron), sulphide (S^2-) to sulphate (SO₄^2-) and burns organic material to carbon dioxide and water. Similarly nitrogen should combine with oxygen to form nitrogen oxide gases which will eventually end up as nitrates in the sea. From being slightly alkaline (pH 8.1- 8.4), the sea would become acid, releasing carbon dioxide from carbonate rocks (e.g. limestones - 10% of all sedimentary rocks). Rain (normally pH 6 due to CO₂, buffered by ammonia) would become much more acid (pH 3) releasing further CO₂from rocks and leaching more nutrients from the soils into the lakes and seas. Under such acid conditions, most mineral nutrients in the soil become unavailable to plants; and aluminium (normally bound in insoluble soil complexes) is leached out into solution in the rivers, lakes and seas where it is toxic to land plants and water life. If equilibrium were to be reached eventually, the Earth would have a hot, high-pressure carbon dioxide atmosphere like Venus. As a result of these processes the oceans would become hot saturated salt solutions containing toxic amounts of nitrate. Under these conditions life in the seas and in the air would be absent. 

Interactions between these domains are also of critical importance. An example is the Ocean-Atmosphere System. The atmosphere is heated at the bottom (at the Earth's surface) producing vigorous convection currents which distribute the heat. Ocean currents, driven mainly by the winds, distribute the heat horizontally. Without this ocean-atmosphere system, the winter pole (i.e. the north polar lands in January) would experience temperatures close to absolute zero, whilst the summer hemisphere (e.g.Australasia) would be extremely hot. 

Steady state

Systems can be maintained away from equilibrium if they continually receive and dissipate (i.e. disperse) large amounts of energy in order to do so. Such systems are called steady state systems. In the physical world they act as nature's safety valves. For instance, the summer sun can cause very great heating of the air at the ground surface producing enormous air- ground temperature differences. If the energy released by the interaction were allowed to build up indefinitely, it would reach fantastic levels and the atmosphere would finally "explode" in an unimaginable catastrophe. Instead the safety valves operate: the excess energy is regularly dissipated by the atmospheric eddies we call storms (thunderstorms, tornadoes, hurricanes, etc). However, these physical steady state systems are highly unstable, persisting only as long as the energy generating them exceeds a critical minimum, and fluctuating only if the energy input does. 

Organisms

The fact that organisms exist is quite unexpected! The principal oxidising agent at the Earth's surface is free oxygen of the atmosphere. The principal reducing agent is organic material. As chemical systems, organisms are highly reactive, so they should steadily be destroyed (oxidised) from the face of the Earth! However, the reason why this does not occur is "kinetics": organic materials have a high activation barrier to burning up so it happens at an infinitesimally slow rate, unless there is something like a forest fire to start off the reaction. Chemical equilibrium for organisms is attained after they have died. However the living world as a whole shows no tendency whatever to come to equilibrium. 

This is because organisms are more than a special kind of physical steady state system. They are homeostatic systems that maintain their characteristic form in a changing environment against wide variations in energy input. Their form is established by the organism itself, not imposed by the environment. By their high activity, organisms speed up the slow natural cycles and in so doing maintain themselves and the rest of the world in a permanently sustainable steady state far removed from chemical equilibrium. 

Through the key processes of respiration and photosynthesis (the most important redox reactions in the world), organisms entirely renew the CO₂in the air every three years or so, and even the much larger volume of oxygen is renewed about every two thousand years. Even the one and a half billion billion tonnes of water on the Earth are eventually split and reconstituted by living things! This is quite amazing because the biosphere (i.e.where the organisms live) is just a very thin "scum" on the Earth's surface. For every atom in the biosphere, there are 700 in the atmosphere, 400,000 in the hydrosphere, and 2 million in the Earth's crust. Yet this insignificant "scum", the biosphere, maintains most of the rest of the world in a steady state adjusted optimally to its own needs. So accurate is the biosphere's system of balances and adjustments that, for example, the oxygen concentration in the air has not measurably varied during the 80 years for which accurate measurements have been available. 

If everything oxidises, what shall organisms do?

In an oxidising Earth, organic compounds should steadily be destroyed. As a matter of fact, random (non-enzymatic) oxidation is a major hazard facing organisms, producing many dangerously reactive chemicals which cause organic compounds to deteriorate and lead to mutations. Vitamin C (a powerful reducing agent), Vitamin E and pro-Vitamin A (ß-carotene) act as anti- oxidants, protecting cells from the ravages of uncontrolled oxidation. Iron poses a specially crucial problem. All life needs iron to mediate the vital redox reactions of metabolism. But in moist oxidising conditions, the most stable form of iron is rust (hydrated Iron III [ferric] oxide) which is highly insoluble, forming large aggregates which would kill organisms by blocking the highways and byways through them and their cells. We would need to drink impossible amounts of water each day just to stop our kidneys clogging with rust! However, organisms have a special soluble "anti-corrosion" protein (ferritin) which binds the iron and stops rust separating out. 

The right energy for the job

There is an important distinction between amount and kindof energy. If the sun's surface temperature was only 550°C (instead of the actual 5500°C) and the Earth much nearer, then the climate would be very similar to what it is. But the predominantly long wavelength radiation would be quite insufficient to sever chemical bonds and life would be impossible. 

People

The cycles of the physical and living world were designed by the Creator to be permanently sustainable, maintaining an optimum environment for living things. People are accountable to their Creator. They can choose to learn the Creator's ways and implement His laws (i.e. principles, properties, standards), or else choose to be wilfully ignorant of them, or deliberately disobey them. In the last century, man's industrial activities have accelerated the natural cycles, but in violent disregard of the Creator's laws. Man is squandering the non- renewable resources of God's world at a phenomenal rate and producing such vast pollution that he threatens to poison the world. In contrast to the noiseless, low energy, economical, self-balancing and self-cleansing activities of the other living domains, man's noisy, high-energy, brutal and wasteful activities conflict violently with the laws governing the universe. Our lives are increasingly dominated by science and technology. Our science needs to be truly integrated: we need to understand how everything in the world relates, under law, to form one harmonious whole, if we are to promote the right policies and remedies. 

Arthur Jones (April 1997)
> <i>This edited article is based on a manuscript published by the Christian Schools' Trust<i>