Gaia. A New Look at Life on Earth

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Gaia

A New Look at Life on Earth

James Lovelock is an independent scientist, inventor, author, and has been an Honorary Visiting Fellow of Green College, University of Oxford, since 1994. He was elected a Fellow of the Royal Society in 1974 and in 1990 was awarded the first Amsterdam Prize for the Environment by the Royal Netherlands Academy of Arts and Sciences. Further awards include the Nonino Prize and the Volvo Environment Prize in 1996, and Japan's Blue Planet Prize in 1997. He was awarded a CBE in 1990 by Her Majesty the Queen.

One of his many inventions was the electron capture detector, which was important in the detection and measurement of CFCs in the atmosphere. He worked with NASA and some of his inventions were adopted in their programme of planetary exploration. His other books include The Ages ofGaia and Homage to Gaia (also published by Oxford University Press) and Gaia: The Practical Science of Planetary Medicine.

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Gaia

A new look at life on Earth

James Lovelock

OXFORD

UNIVERSITY PRESS

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Great Clarendon Street, Oxford 0x2 6DP

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First published 1979

First issued as an Oxford University Press paperback 1982

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Reprinted 1995

Reissued, with a new preface and corrections, 2000

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	Preface vii
1	Introductory 1
2	In the beginning 12
3	The recognition of Gaia 30
4	Cybernetics 44
5	The contemporary atmosphere 59
6	The sea 78
7	Gaia and Man: the problem of pollution 100
8	Living within Gaia 115
9	Epilogue 133
	Definitions and explanations of terms 143
	Further reading 147

{vii}

Preface

Twenty-six years ago when I first started writing this book, I had no clear idea of what Gaia was although I had thought deeply about her. What I did know was that the Earth was different from Mars and Venus. It was a planet with apparently the strange property of keeping itself always a fit and comfortable place for living things to inhabit. I had the idea that somehow this property was not an accident of its position in the Solar System but was a consequence of life on its surface. The word 'Gaia' came from my friend and near neighbour, the novelist William Golding. He thought that such an idea should be named Gaia after the Greek goddess of the Earth.

In those days of the early 1970s, we were still innocent about the environment. Rachel Carson had given us cause to worry, farmers were destroying the pleasant countryside we knew by the overuse of chemicals but it all still seemed all right. Global change, biodiversity, the ozone layer, and acid rain all were ideas barely visible in science itself, still less of public concern. We were all to some extent participants in the cold war and far more of our time went into serving in that war than we ever realized. As a scientist involved with NASA's planetary exploration programme I was only dimly aware that the lift vehicles that took our experiments to Mars and beyond would never have been made for pure science alone. We were riding the war horses of the silent war between the Soviet Union and the United States. The navigation system that faultlessly found its way to a chosen destination on Mars could also have precisely enabled the demolition of an enemy missile battery.

The cold war distorted much more than space science. To my mind, the most serious damage done was to our understanding of our own planet. We were naturally fearful of the consequences of a hot war fought with nuclear weapons and knew that at the least it {viii} would destroy the civilizations of the combatants. These real fears led to the growth in the West of the Campaign for Nuclear Disarmament (CND) and it became the first international environmental movement. So pressing were our anxieties over the consequences of nuclear war that at times it seemed that nuclear radiation was the quintessence of our fears. The dangers of habitat destruction and the inflation of the air with greenhouse gases seemed remote and trivial concerns in the 1970s and 1980s, especially to those campaigning for the abolition of everything nuclear.

When the cold war fizzled out in the last years of the century we had an environmental movement which included active members who came from the old CND and they were still mainly fighting the industrial and military systems of the West that sustained nuclear weapons. It was easy for them to transfer their campaign to attacking all science-based large companies of the First World especially where there was a link, however tenuous, with a threat to humanity.

I consider this politicization of Green thought and action has led us dangerously astray. It stops us from realizing that it is not them, the multinational companies or the state industries of Russia and China that are wholly to blame for our fast degrading world. Our much too vociferous advocates, the consumer lobbies, and we the consumers are equally responsible for the gaseous greenhouse and the extinction of wildlife. The multinational companies would not exist if we had not demanded their products and at a price that forces them to produce without enough care for the consequences. In our belief that all that matters is the good of humankind we foolishly forget how much we depend upon all the other living things on Earth.

We need to love and respect the Earth with the same intensity that we give to our families and our tribe. It is not a political matter of them and us or some adversarial affair with lawyers involved; our contract with the Earth is fundamental, for we are a part of it and cannot survive without a healthy planet as our home. I wrote this book when we were only just beginning to glimpse the true nature of our planet and I wrote it as a story of discovery. If you are someone wanting to know for the first time about the idea of Gaia, {ix} it is the story of a planet that is alive in the same way that a gene is selfish.

This book is the story of Gaia, about getting to know her without understanding what she is. Now twenty-six years on, I know her better and see that in this first book I made mistakes. Some were serious, such as the idea that the Earth was kept comfortable by and for its inhabitants, the living organisms. I failed to make clear that it was not the biosphere alone that did the regulating but the whole thing, life, the air, the oceans, and the rocks. The entire surface of the Earth including life is a self-regulating entity and this is what I mean by Gaia. I was also foolish to suggest that we could warm the Earth in the event of an imminent ice age by deliberately releasing chlorofluorocarbons into the air, exploiting their potent greenhouse effect to keep us warm. In those days of innocence, the technological fix was respectable. I have not altered the original text to correct any of these mistakes, although a parenthetic correction follows these errors. The story is as it was and lets you see how the idea of Gaia developed, not only in science, but also as part of thought on a wider scale. I never imagined in 1974 just how wide this might be.

When I started to write in 1974 in the unspoilt landscape of Western Ireland, it was like living in a house run by Gaia, someone who tried hard to make all her guests comfortable. I began more and more to see things through her eyes and slowly dropped off, like an old coat, my loyalty to the humanist Christian belief in the good of mankind as the only thing that mattered. I began to see us all, as part of the community of living things that unconsciously keep the Earth a comfortable home, and that we humans have no special rights only obligations to the community of Gaia.

On 4 July 1994, the United States of America awarded the Liberty Medal to the Czech president Vaclav Havel. The title of his speech of acceptance was, 'We are not alone nor for ourselves alone'. He recognized that the Modern age has ended, the artificial world order of the past decades has collapsed and a new more just order has not yet emerged. He went on to say that we are now where classically modern solutions do not give a satisfactory response. We need to anchor the idea of human rights and freedoms in a different {x} place and in a different way than has been done so far. Paradoxically, he said, inspiration for the renewal of this lost integrity can again be found in science. In a science that is new— post modern—a science producing ideas that in a certain sense allow it to transcend its own limits. He gave two examples: first, the anthropic cosmological principle where science finds itself on the border with myth which returns us to an ancient idea, namely, that we are not just an accidental anomaly. Second, the Gaia theory in which all life and all the material parts of the Earth's surface make up a single system, a kind of mega-organism, and a living planet. In Havel's words, 'According to the Gaia Hypothesis, we are parts of a greater whole. Our destiny is not dependent merely on what we do for ourselves but also on what we do for Gaia as a whole. If we endanger her, she will dispense with us in the interests of a higher value—life itself The statesman Havel's acceptance that human rights are not enough is timely and not only for ourselves as humans but also for Gaia. She was first expressed in this book at a time when the science of Gaia was no more than the noticing of a stable planet made of unstable parts. Something wholly unexpected, something improbable, as it must have seemed when the world was first found round, not flat; how Gaia worked was still ten years from discovery. Because of my ignorance twenty-six years ago, I wrote as a storyteller and gave poetry and myth their place along with science. In the preface of the first edition, I warned:

Occasionally it is difficult, without excessive circumlocution, to avoid talking of Gaia as if she were known to be sentient. This is meant no more seriously than is the appellation 'she' when given to a ship by those who sail in her, as a recognition that even pieces of wood and metal when specifically designed and assembled may achieve a composite identity with its own characteristic signature, as distinct from being the mere sum of its parts.

Most of the criticism of Gaia has come from scientists who read the first edition of this book. None of them appeared to notice the disclaimer, nor did they read the ten or so papers on Gaia in peer-reviewed scientific journals. The critics took their science earnestly {xi} and to them mere association with myth and storytelling made it bad science. My disclaimer was about as much use as is the health warning on a packet of cigarettes to a nicotine addict.

The force of their objections slowed the natural development of Gaia theory. Until 1995 it was nearly impossible for a scientist anywhere to publish a paper on Gaia, unless to disprove or disparage it; now at last it is a candidate theory awaiting approval. Unfortunately for me, the way forward splits at a cruel bifurcation. To establish Gaia as a fact I must take the first path, that of science. As a guide on the best way to live with the Earth, it will only be believed if it comes with majority support from the scientific community—politicians and governmental agencies dare not act on myth—and demand scientific approval. To keep Gaia as something we all can understand I must take the second path, the one that goes to the postmodern world. Here science itself is questioned, but the Gaia of this book is acceptable even to statesmen and states-women. Which of these paths should I take?

I have tried for them both by rewriting my second book, The Ages ofGaia, so that it is specifically for scientists, and leaving this book as it was. If I were to rewrite this first book in scientifically correct language, and make it esoteric, it would be incomprehensible. It would be opaque not only to non-scientists, but to engineers, physicians, and practical environmentalists who need moral guidance as well as technology within their work. The few alterations I have made to this book are to correct facts of science that were wrong, such as that the release of methane to the air is 500, not 1,000, million tons a year, as was thought by scientists twenty-six years ago. I have tried to define that vague word 'biosphere'. Originally, it was a precise geographical term defining the region of the Earth where living organisms existed. Gradually, it lost precision and became a vogue word meaning anything from a superorganism like Gaia, to no more than a catalogue of all living organisms. In the first edition, I tended to use it, as many do, as a synonym for Gaia. At the time, I did not know the full definition of either of them and used them interchangeably for no reason other than literary variation. In this edition, the relationship between biosphere and Gaia is like that between your body and you. The biosphere is the {xii} three-dimensional geographic region where living organisms exist. Gaia is the superorganism composed of all life tightly coupled with the air, the oceans, and the surface rocks.

It follows that this book is not for hard scientists. If they read it in spite of my warning, they will find it either too radical or not scientifically correct. Yet, I am a scientist and I am deeply committed to science as a way of life. I did not write this book to irritate my colleagues. None of us then knew much about the Earth. I differed from them because the view from space let me see the Earth from the top down, not in the usual reductionist way from the bottom up. The external, holistic, view unexpectedly puts me in tune with both the post-modern world and with mainstream science before it started its love affair with reductionism.

The French Nobel laureate, Jacques Monod, in his book Chance and Necessity castigated holistic thinkers like me as 'very stupid people'. I salute him as most distinguished among scientists but still think that he was wrong and that science needs the top-down approach as much as it needs reduction. If the whole of present human scientific knowledge were entered in a single book, it would be beyond the comprehension of anyone now alive. Scientists in their whole working lives rarely ever leave a small subsection of a single chapter. While no one could understand the whole book, at least with the top-down holistic look we can see the table of contents. Having said this, I recognize that scientists now, deep into the reduction of a single page are uninterested in the book, or even other chapters of it. Broad ideas like Gaia are anathema to them. They see Gaia as metascience, something like a religious faith and therefore from their deeply held materialistic beliefs, something to be rejected.

Change is in the air, perhaps science grows generous again. Encouraging signs first appeared in Oxford in April 1994, at a scientific meeting to the title 'The Self Regulating Earth'. Here a wish was expressed to see established a forum for the top-down, physiological style discussion of Earth science topics. Even opponents of the original Gaia hypothesis, wished for a society where they could discuss ideas outside the essential but limited bottom-up approach of mainstream science. Subsequent meetings in Oxford in 1996 and {xiii} 1999 expanded and developed a holistic view of the Earth. Now most scientists appear to accept Gaia theory and apply it to their research, but they still reject the name Gaia and prefer to talk of Earth System Science, or Geophysiology, instead.

This local and partial acceptance of the real science of Gaia, after twenty-six years in the wilderness, was not without conditions. Important among them is the demand that the new science of Gaia, Geophysiology, must be purged of all reference to mystical notions of Gaia the Earth Mother. Even metaphorical phrases such as 'Gaia likes it cool' to express the observation that the Earth system appears to flourish in glacial times must be cast out. Before Geophysiology is accepted into the ample but strait-laced bosom of science, it must be scientifically correct.

This means speaking science in its own strict language, heavy and laden with abstract nouns and the passive tense though it may be. The problems of our ailing society inhabiting an unhealthy planet are serious and this is no time to quibble over the rules. Science is almost certainly needed to keep our civilization alive, and if Gaia is a good model of the Earth, then I must express it in scientific language. It is like the way a soldier has to accept military discipline when enlisting to fight in a just war.

The community of environmentalists include many who claim an ownership of Gaian ideas and they have a case. Jonathan Porritt put it well: Gaia is too important as a focus for Green thought and action to be conscripted by science. Some accused me of betraying Gaia. Fred Pearce, in an entertaining article in the New Scientist of May 1994, captured the spirit of that Oxford meeting when he asked for Gaia to be acknowledged by science and the humanities both.

These are anxious and exciting times and remind me of the days before the Second World War when many free spirits saw the need to accept conscription. They knew that if war was to lead to a just and successful peace its objectives must be kept in mind as well as the disciplined mechanics of military action. There is no betrayal of Gaia, we need the restraint of scientific conduct for investigation and theory testing and we need the poetry and emotion that moves us and keeps us in good heart while the battle goes on. {xiv}

As a scientist, I submit wholly to scientific discipline and this is why I sanitized my second book The Ages ofGaia and hopefully made it acceptable to scientists. As a man I also live in the gentler world of natural history, where ideas are expressed poetically and so that anyone interested can understand and that is why this book remains almost unchanged. One critic referred to it scathingly as a fairy story about a Greek goddess. In a way, he was right. It was also a long letter to a yet unknown love, with science as such an incidental part as it was in Primo Levi's Periodic Table. Written in Ireland perhaps it is Irish in spirit. To my scientist friends who wanted it to lead somewhere else I would say: if you wanted to go there, you should not have started from here.

The old Gaia was an entity that kept herself and all who lived with her comfortable throughout time and season. She worked so that the air, the oceans, and the soil were always fit for life. She was something that almost everyone could understand. I intended Gaia of this first book to enliven and entertain a walk in the countryside or a journey to a new and unvisited place. It tells how the apparent random destructiveness of a forest fire might be part of a way to keep oxygen in the air at the safe level of 21 per cent. It describes how my friend Andrew Watson showed by simple experiments that even 25 per cent of oxygen in the air would be disastrous. Trees could not grow to make forests. With that much oxygen, fire would destroy them while still half grown. No one had thought of the air, or the oxygen, that way before.

In Chapter 6, we take a walk along the seashore, pick up seaweeds and sniff their odd sweet sulphury smell, and wonder about their function in Gaia. I never guessed twenty years ago that these won-derings would lead to what is now a large scientific enterprise employing hundreds of scientists worldwide. What was in truth no more than a nature walk along the shore in Ireland has become a major research. Scientists now seek the connection between the growth of ocean algae and the climate. They measure the output of gases that come from the sea because of an algal presence. They observe the oxidation of these gases in the air to make the seeds from which clouds form. They look at the effect of these events on climate and on the way that climate change feeds back on the {xv} growth of the algae. It is an investigation in its early stages, full of argument and full of vigour.

Deerfly, although they are as much a part of the natural world as we are, can make a walk through a Canadian forest in summertime a misery. Among the species of scientists, there are similar irritating types whose careers grow from the blood sucked from large and ill-considered hypotheses. Their existence is needed in the natural selection of theories. Without these gadflies, we would be taking bogus ideas like biospheres in bottles, or cold fusion, seriously. The Gaia hypothesis was a vague speculation before the blood was drawn to leave the leaner and more scientifically acceptable Gaia theory. For this I am grateful to the critics.

During the next and scientifically correct stages in the development of the theory, it may become all but incomprehensible to any but its own scientific practitioners. Do not make the mistake of those disgruntled humanists who will reject Gaia because it is part of a science they do not understand. There is nothing solid in their claim that science is malign or bogus. Science is wonderfully self-cleansing and bad theories have a short life.

Some of the preface of the first edition seems to follow the above text naturally so I have included it as part of what follows. The idea of Mother Earth or, as the Greeks called her, Gaia, has been widely held throughout history and has been the basis of a belief that coexists with the great religions. Evidence about the natural environment accumulates and the science of ecology grows. This has led to speculation that the biosphere may be more than the habitat of all living things. Ancient belief and modern knowledge have fused emotionally in the awe with which astronauts with their own eyes and we by television have seen the Earth revealed in all its shining beauty against the deep darkness of space. Yet, this feeling, however strong, does not prove that Mother Earth lives. Like a religious belief, it is scientifically untestable and therefore incapable in its own context of further rationalization.

The idea of the Earth as a kind of living organism, something able to regulate its climate and composition so as always to be comfortable for the organisms that inhabited it, arose in a most respectable scientific environment. It came to me suddenly one afternoon in {xvi} 1965 when I was working at the Jet Propulsion Laboratory (JPL) in California. It came because my work there led me to look at the Earth's atmosphere from the top down, from space. Such a look forces questions about the composition of the air we breathe not previously asked. We all take our first breath of life-sustaining air and from then on take it for granted. We are confident it will be there to breathe as constant in composition as is the Sun constant in its rising and setting. Air is invisible almost intangible but if you look at it from above, from space you see it as something new, something unexpected. It is the perfect stained glass window of the world, but also it is a strange mixture of unstable, almost combustible gases. The air is a mixture that somehow always keeps constant in composition. My flash of enlightenment that afternoon was the thought that to keep constant something must be regulating it and that somehow the life at the surface was involved.

The quest for Gaia, which began nearly thirty-five years ago has ranged through the territories of many different scientific disciplines, indeed from astronomy to zoology. Such journeys are lively, for professors jealously guard the boundaries between their sciences. I had to learn a different arcane language in each territory I passed through. In the ordinary way a grand tour of this kind would be extravagantly expensive and unproductive in its yield of new knowledge; but just as trade often still goes on between nations at war, it is also possible for a chemist to travel through such distant disciplines as meteorology or physiology, if he has something to barter. Usually this is a piece of hardware or a technique. I was fortunate to work briefly with A. J. P. Martin, who developed among other things the important chemical analytical technique of gas chromatography. During that time, I added some embellishments that extended the range of his invention. One of these was the so-called electron capture detector. It is a device of exquisite sensitivity, which discovered pesticide residues in all creatures of the Earth, from penguins in Antarctica to the milk of nursing mothers in the USA. It was this discovery that helped Rachel Carson to write her immensely influential book, Silent Spring. It provided her with the evidence that these toxic chemicals were ubiquitous worldwide. It justified her concern that they threatened the organisms of the {xvii} biosphere. Electron capture has continued to reveal minute but significant quantities of other toxic chemicals in places they ought not to be. Among these intruders are: PAN (peroxyacetyl nitrate), a toxic component of smog; the PCBs (polychlorobiphenyls) in the remote natural environment. It has also revealed the presence of the chlorofluorocarbons and nitrous oxide, substances that deplete the strength of ozone in the stratosphere.

Electron capture detectors were undoubtedly the most valued of the trade goods which enabled me to pursue my quest for Gaia through the various scientific disciplines, and indeed to travel literally around the Earth itself. My role as a tradesman made interdisciplinary journeys feasible, but they have not been easy. The past thirty years have witnessed a great deal of turmoil in the life sciences, particularly in areas where science has been drawn into the process of politics.

When Rachel Carson made us aware of the dangers arising from the mass application of toxic chemicals, she presented her arguments in the manner of an advocate, not a scientist. In other words, she selected the evidence to prove her case. The chemical industry, seeing its livelihood threatened by her action, responded with an equally selective set of arguments, chosen in defence. This may have been a fine way of achieving justice, and perhaps in this instance it was scientifically excusable; but it seems to have established a pattern. Since then a great deal of scientific argument and evidence concerning the environment is presented as if in a courtroom or at a public enquiry. I cannot say too often that, although this may be good for the democratic process, it is bad for science. Truth is said to be the first casualty of war. Being used selectively in evidence to prove a case in law also weakens it.

The first six chapters of this book are not concerned with matters of social controversy—at least not yet. In the last three chapters, however, which are about Gaia and mankind; I am aware of having moved on to a battleground where powerful forces are in action. President Havel's moving address, the constant support of Sir Crispin Tickell, Jonathon Porritt, and other leaders gives me reason to feel that Gaia is significant beyond science. If only to warn, that to act for the good of humankind alone is not enough. When I first {xviii} started this book, twenty-six years ago, the future looked good. There were problems looming with people and the environment but all seemed capable of sensible or scientific solution. Now the prospect is at best doubtful. One of the few certainties about the Earth is that we have changed the atmosphere and the land surface more than it has changed by itself in millions of years. These changes still go on and ever faster as our numbers grow. Ominously nothing yet seems to have happened more noticeable than the ozone hole over Antarctica. Most politicians believe that all we need is growth and trade and that environmental problems can be fixed technologically. This normal human optimism reminds me of a time in London in the Second World War. I had the job of checking the quality of the air in an underground air raid shelter. It was in a disused tube tunnel that ran through the soft mud alongside the River Thames. To my dismay I found that vandals had taken away most of the bolts holding together the steel plates of the tunnel to sell for scrap. It would have taken only a small disturbance to burst the tunnel and flood it. The denizens of the shelter did not seem worried about the possibility of being drowned in mud. They were more frightened by the noisy, but in my judgement, less dangerous war on the surface above them. In a way we are still taking away the bolts of the tunnel and feel confident that what we do is harmless because so far nothing has happened.

Shortly after I wrote the first edition, I came across an article by Arthur Redfield in the American Scientist of 1958. In it he put forward the hypothesis that the chemical composition of the atmosphere and oceans was biologically controlled. He produced supporting evidence drawn from the distribution of the elements. I am glad that I saw Redfield's contribution to the development of the Gaia hypothesis in time to acknowledge it. I now know that there were many others who had these and similar thoughts, including the Russian scientist Vernadsky, and G. E. Hutchinson. I most regret my ignorance then of James Hutton, often known as the father of Geology, who in 1785 compared the global cycling of water with the blood circulation of an animal. The notion of Gaia, of a living Earth, has not in the past been acceptable in the mainstream and consequently seeds sown in {xix} earlier times did not flourish but instead remained buried in the deep mulch of scientific papers.

In a subject so broadly based as that of this book there was the need for much advice and I thank the many scientific colleagues who patiently and unstintingly gave their time to help me, especially Professor Lynn Margulis who has been my constant colleague and guide. I am also grateful to Professor C. E. Junge of Mainz and to Professor B. Bolin of Stockholm, who first encouraged me to write about Gaia. I thank my colleagues Dr James Lodge of Boulder, Colorado, Sidney Epton of Shell Research Limited, and Professor Peter Fellgett of Reading, who encouraged me to continue the quest.

My special thanks go to Evelyn Frazer, who took the draft of this book and most skilfully turned the disordered mosaic of sentences and paragraphs into a readable whole. Finally, I wish to record my debt to my first wife Helen Lovelock, who not merely produced the typescript but also, in her lifetime, kept the environment in which writing and thinking were possible. Contrary to all reasonable expectation, life began again for me at 70 with my second wife Sandy Lovelock, for whom it could be said this book was written since her reading it brought us together.

I have listed at the end of the book, arranged by chapter, the principle sources of information and suggestions for additional reading, together with some definitions and explanations of terms and of the system of units of measurement used in the text.

{143}

Definitions and explanations of terms

Abiohgical

Literally without life, but in practice a specialist adjective to describe situations where life has played no part in the end result or product. A piece of rock from anywhere on the surface of the moon has been shaped and formed abiologically, whereas almost all rocks from the Earth's surface have to some extent, great or small, been changed by the presence of life.

Acidity and pH

In common scientific usage acids are substances which readily donate positively charged hydrogen atoms, or protons, as chemists call them. The strength of a solution of an acid in water is conveniently expressed in terms of the concentration of protons it bears. This usually varies from about 0.1 per cent with very strong acids to one part in a thousand million for a very weak acid such as carbonic acid, the acid of 'soda water'. Strangely, chemists express acidity backwards in logarithmic units called pH, so that a strong acid is pHl and a very weak one pH7.

Aerobic and Anaerobic

Literally with and without air. Words used by biologists to describe environments which are respectively surfeited with or deficient in oxygen. All surfaces in contact with the air are aerobic, as are most of the oceans, rivers, and lakes which bear oxygen in solution. Muds and soil and the guts of animals are all greatly deficient in oxygen and hence called anaerobic. Here live micro-organisms similar to those which inhabited the Earth's surface before oxygen entered the atmosphere.

Biosphere

The biosphere was defined in the last century by the Austrian geologist Suess as the geographical region of the Earth where life is found. It has subsequently become a vogue, and consequently, vague word meaning anything from a superorganism like Gaia to a catalogue of all the species of organisms. In this book I have used it in its original geographic sense. {144}

Equilibrium and Steady State

These technical terms refer to two common conditions of stability. A table stands secure on its four legs and is at equilibrium. A horse standing still is in the steady state because it actively, although unconsciously, maintains its position. If it dies, it collapses.

Gaia Hypothesis

This postulates that the physical and chemical condition of the surface of the Earth, of the atmosphere, and of the oceans has been and is actively made fit and comfortable by the presence of life itself. This is in contrast to the conventional wisdom which held that life adapted to the planetary conditions as it and they evolved their separate ways. This describes the original Gaia hypothesis which we now know to be wrong. Life does not regulate or make the Earth comfortable for itself. I now think that regulation, at a state fit for life, is a property of the whole evolving system of life, air, ocean, and rocks. This could be called Gaia Theory since it has a mathematical basis in the model Daisyworld and because it makes testable predictions.

Homoeostasis

A word invented by the American physiologist, Walter Cannon. It refers to that remarkable state of constancy in which living things hold themselves when their environment is changing.

Life

A common state of matter found at the Earth's surface and throughout its oceans. It is composed of intricate combinations of the common elements hydrogen, carbon, oxygen, nitrogen, sulphur, and phosphorus with many other elements in trace quantities. Most forms of life can instantly be recognized without prior experience and are frequently edible. The state of life, however, has so far resisted all attempts at a formal physical definition.

Molarity/Molar solution

Chemists prefer to express the strength of solutions in what they call molarity because this provides a fixed standard for comparison. A mole, or gram-molecule, is the molecular weight of a substance expressed in grams. A molar solution has a concentration of 1 mole of solute per litre. Thus 0.8 molar solution of common salt, sodium chloride, contains the same number of molecules as 0.8 molar solution of an uncommon salt, lithium perchlorate, but because sodium chloride has a lower molecular weight than lithium perchlorate, the one solution contains 4.7 per cent solids by weight {145} and the other 10.3 per cent solids—yet both contain the same number of molecules and have the same salinity.

Oxidation and reduction

Chemists refer to substances and elements which are deficient in negatively charged electrons as oxidizers. These include oxygen, chlorine, nitrates, and many others. Substances rich in electrons, such as hydrogen, most fuels, and metals, are called reducing. The oxidizers and reducers usually react, producing heat, and the process is called oxidation. The ashes and spent gases of the fire can be worked upon chemically to restore the original elements. When this is done to carbon dioxide to make carbon, the process is called reduction. It happens all the time in green plants and algae when the sun shines upon them.

Ozone

A very poisonous and also explosive blue gas. It is a rare form of oxygen in which three instead of two oxygen atoms are joined together. It is present in the air we breathe, normally at only one-thirtieth of a part per million, but in the stratosphere at five parts per million.

Stratosphere

A part of the air lying directly above the troposphere and bounded by the tropopause at 7 to 10 miles high and the mesopause at around 40 miles high. These bounds vary in height with place and season and mark the limits within which the temperature rises rather than falls with increasing altitude. The stratosphere is the site of the ozone layer.

Troposphere

The principal part, 90 per cent, of the air, lying between the Earth's surface and the boundary layer, the tropopause, 7 to 10 miles above. It is the only region of the atmosphere encountered by living things and the place where the weather, as we know it, takes place.

Systems of units and measurement

Many of us are obliged to live in a binumerate state as the old natural system of measurements based upon feet and thumbs and resident in duodecimal or even heptadecimal numbers dies away. Decimal metric scientific units seem so rational and sensible but I suspect that many have more than a sneaking preference for the yard, which can be paced, as against the metre which means nothing real to them. It has even been said that the metric system was part of Napoleon's psychological warfare — a sort of intellectual terrorism to {146} dismay the enemy. The battle between the systems is still on, even after 150 years, and those who imagine that the old system is just some quaint British anachronism should consider that the USA still lives by feet and pounds and gallons and that probably more than half of all the engineering and high technology of the world is in non-metric units. Bearing this in mind, I have used in the text whichever system seemed more appropriate in the context.

Thus to talk of the environmental temperatures in degrees Celsius is less comprehensible to most English-speaking people than to talk in degrees Fahrenheit. Yet no one would list the sun's surface temperature as anything other than 5,500 degrees Celsius or think of boiling liquid nitrogen as other than –180 degrees Celsius.

The convenient prefixes kilo, mega, giga (one thousand, one million, one thousand million respectively) are used to multiply such units as tons, years, and so on. For small quantities the similar prefixes milli, micro, and nano can be used to denote one thousandth, one millionth, and one thousand millionth respectively. Scientific notation is normally used: i.e. 1,500 million is expressed as 1.5 × 10⁹ and one three hundred millionth as 3.3 × 10^–9.

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Contents

Preface

Definitions and explanations of terms

Further reading