The unity of the Earth

Having described attitudes that are not balanced or harmonious in their relationship to the Earth and that fail to contribute to sustainability, I now turn to describe attitudes that adequately address the problems that I have been presenting in this book, namely the damage to the Earth's ecosystems destroying species at an alarming rate and the damage to large numbers of the world's peoples especially those who are already poor and disadvantaged. These are bound to represent the responsibilities that we all have not just for each other but also for the larger world of all living things. We are, after all, part of that larger world. There is good scientific justification for this. We are becoming increasingly aware of our dependence on the rest of nature and of the interde-pendencies that exist between different forms of life, between living systems and the physical and chemical environment that surrounds life on the Earth -and indeed between ourselves and the rest of the universe.

The scientific theory named Gaia after the Greek Earth goddess and publicised particularly by James Lovelock emphasises these interdependencies.5 Lovelock points out that the chemical composition of the Earth's atmosphere is very different from that of our nearest planetary neighbours, Mars and Venus. Their atmospheres, apart from some water vapour, are almost pure carbon dioxide. The Earth's atmosphere, by contrast, is 78% nitrogen, 21% oxygen and only 0.03% carbon dioxide. So far as the major constituents are concerned, this composition has remained substantially unchanged over many millions of years - a fact that is very surprising when it is realised that it is a composition that is very far from chemical equilibrium.

This very different atmosphere on the Earth has come about because of the emergence of life. Early in the history of life, plants appeared which photosyn-thesise, taking in carbon dioxide and giving out oxygen. There followed other living systems that 'breathe', taking in oxygen and giving out carbon dioxide. The presence of life therefore influences and effectively controls the environment to which living systems in turn adapt. It is the close match of the environment to the needs of life and its development that seems so remarkable and which Lovelock has brought to our notice. He gives many examples; I will quote one concerned with oxygen in the atmosphere. There is a critical connection between the oxygen concentration and the frequency of forest fires.6 Below an oxygen concentration of 15%, fires cannot be started even in dry twigs. At concentrations above 25% fires burn extremely fiercely even in the damp wood of a tropical rainforest. Some species are dependent on fires for their survival; for instance, some conifers require the heat of fire to release their seeds from the seed pods. Above 25% concentration of oxygen there would be no forests; below 15%, the regeneration that fires provide in the world's forests would be absent. The oxygen concentration of 21% is ideal.

It is this sort of connection that has driven Lovelock to propose that there is tight coupling between the organisms that make up the world of living systems and their environment. He has suggested a simple model of an imaginary world called Daisyworld (see box below), which illustrates the type of feedback mechanisms that can lead to this coupling and exert control. This model is similar to one he proposed for the biological and chemical history of the Earth during the first 1000 million years after primitive life first appeared on the Earth some 3500 million years ago.

The real world is, of course, enormously more complex than Daisyworld, which is why the Gaia hypothesis has led to so much debate. Lovelock's first statement in 1972 of the hypothesis was that 'Life, or the biosphere, regulates or maintains the climate and the atmospheric composition at an optimum for itself.'7 In his later writings he introduced the analogy between the Earth and a living organism, introducing a new science which he calls geophysiol-ogy8 - a more recent book is entitled Gaia: The Practical Science of Planetary Medicine.

An advanced organism such as a human being has many built-in mechanisms for controlling the interactions between different parts of the organism and for self-regulation. In a similar way, Lovelock argues, the ecosystems on the Earth are so tightly coupled to their physical and chemical environments that the ecosystems and their environment could be considered as one organism with an integrated 'physiology'. In this sense he believes that the Earth is 'alive'.

That elaborate feedback mechanisms exist in nature for control and for adaptation to the environment is not in dispute. But many scientists feel that Lovelock has gone too far in suggesting that ecosystems and their environment can be considered as a single organism. Although Gaia has stimulated much scientific comment and research, it remains a hypothesis.9 What the debate has done, however, is to emphasise the interdependencies that connect all living systems to their environment - the biosphere is a system in which is incorporated a large measure of self-control.

There is the hint of a suggestion in the Gaia hypothesis that the Earth's feedbacks and self-regulation are so strong that we humans need not be concerned about the pollution we produce - Gaia has enough control to take care of anything we might do. Such a view fails to recognise the effect on the Earth's system of substantial disturbances, in particular vulnerability of the environment with respect to its suitability for humans. To quote Lovelock:

Gaia, as I see her, is no doting mother tolerant of misdemeanours, nor is she some fragile and delicate damsel in danger from brutal mankind. She is stern and tough, always keeping the world warm and comfortable for those who obey the rules, but ruthless in her destruction of those who transgress. Her unconscious goal is a planet fit for life. If humans stand in the way of this, we shall be eliminated with as little pity as would be shown by the micro-brain of an intercontinental ballistic nuclear missile in full flight to its target.

The Gaia scientific hypothesis can help to bring us back to recognise two things: fi rstly, the inherent value of all parts of nature, and secondly our dependence, as human beings, on the Earth and on our environment. Michael Northcott has pointed out, for instance, that Gaian theory 'suggests all human beings, all creatures, are relationaly interconnected by carbon cycle of the planet' .12 Gaia remains a scientifi c theory - although some have seen it as a religious idea, supporting ancient religious beliefs. Many of the world's religions have drawn attention to the close relationship between humans and the Earth.

The Native American tribes of North America lived close to the Earth. One of their chiefs when asked to sell his land expressed his dismay at the idea and said, 'The Earth does not belong to man, man belongs to the Earth. All things are connected like the blood that unites us all .'13 An ancient Hindu saying, 'The Earth is our mother, and we are all her children' 14 also emphasises a feeling of closeness to the Earth. Those who have worked closely with indigenous peoples have given many examples of the care with which, in a balanced way, they look after the trees, plants and animals in their local ecosystem .15

The Islamic religion teaches the value of the whole environment, for instance in a saying of the prophet Mohammed: 'He who revives a dead land will be rewarded accordingly, and that which is eaten by birds, insects and animals out of that land will be charity provided by God' - so pointing both to our duty to care for the natural environment and our obligation to allow all living creatures their rightful place within it .16

Judaism and Christianity share the stories of creation in the early chapters of the Bible that emphasise the responsibility of humans to care for the Earth -we shall refer to these stories again later on in the chapter. Further on in the ft ft ft ft ft ft. ft ft tf y y tfy tfy y

Brightness of the Sun and temperature increases

Figure 8.1 Daisyworld.

Daisyworld and life on the early Earth

Daisyworld is an imaginary planet spinning on its axis and orbiting a sun rather like our own. Only daisies live in Daisyworld; they are of two hues, black and white. The daisies are sensitive to temperature. They grow best at 20 °C; below 5 °C they will not grow and above 40 °C they wilt and die. The daisies influence their own temperature by the way they absorb and emit radiation: black ones absorb more sunlight and therefore keep warmer than white ones.

In the early period of Daisy-world's history (Figure 8.1), the sun is relatively cool and the black daisies are favoured because, by absorbing sunlight, they can keep their temperature closest to 20 °C. Most of their white cousins die because they reflect sunlight and fail to keep above the critical 5 °C.

However, later in the planet's history, the sun becomes hotter. Now the white daisies can also flourish; both sorts of daisies are present in abundance. Later still as the sun becomes even hotter the white daisies become dominant as conditions become too warm for the black ones. Eventually, if the sun continues to increase its temperature even the white ones cannot keep below the critical 40 °C and all the daisies die.

Daisyworld is a simple model employed by Lovelock to illustrate the sort of feedbacks and self-regulation that occur in very much more complex forms within the living systems on the Earth.11

Lovelock proposes a similar simple model as a possible description of the early history of life on the Earth (Figure 8.2). The dashed line shows the temperature that would be expected on a planet possessing no life but with an atmosphere consisting, like our present atmosphere, mostly of nitrogen with about 10% carbon dioxide. The rise in temperature occurs because the sun gradually became hotter during this period. About 3500 million years ago primitive life appeared. Lovelock, in this model, assumes just two forms of life, bacteria that are anaerobic photosynthesisers - using carbon dioxide to build up their bodies but not giving out oxygen - and bacteria that are decomposers, converting organic matter back to carbon dioxide and methane. As life appears the temperature decreases as the concentration of the greenhouse gas, carbon dioxide, decreases. At the end of the period about 2300 million years ago, more complicated life appears; there is an excess of free oxygen and the methane abundance falls to low values, leading to another fall in temperature, methane also being a greenhouse gas. The overall influence of these biological processes has been to maintain a stable and favourable temperature for life on the Earth.

Time (billions of years before present)

Figure 8.2 Model of the Earth's early history, as proposed by Lovelock.

Time (billions of years before present)

Figure 8.2 Model of the Earth's early history, as proposed by Lovelock.

Old Testament detailed instructions are given regarding care for the land and the environment. 17 Christianity was described by William Tfemple, Archbishop of Canterbury 60 years ago, as 'the most materialistic of the great religions'. Because of its central belief that God became human in Jesus (an event Christians call the Incarnation), Temple goes on to say 'by the very nature of its central doctrine Christianity is committed to a belief .. .n the reality of matter and its place in the divine scheme' .18 For the Christian, the twin doctrines of Creation and Incarnation demonstrate God's interest in and concern for the Earth and the life it contains .

In looking for themes that emphasise the unity between humans and their environment, we need not confi ne ourselves to the Earth. There is a very much larger sphere in which a similar perspective of unity is becoming apparent. Some astronomers and cosmologists, overwhelmed by the size, scale, complexity, intricacy and precision of the Universe, have begun to realise that their quest for an understanding of the evolution of the Universe right from the Big Bang some 14 000 million years ago is not just a scientifi c project but a search for meaning. 19 Why else has Stephen Hawking's book A Brief History of Time20 become one of the bestsellers of our time?

In this new search for meaning, the perspective has arisen that the Universe was made with humans in mind - an idea expressed in some formulations of the 'anthropic principle'. 21 Two particular pointers emphasise this. Firstly, we have already seen that the Earth itself is fi tted in a remarkable way for advanced forms of life. Cosmology is telling us that, in order for life on our planet to be possible, the Universe itself at the time of the Big Bang and in its early history needed to be 'fi ne- tuned' to an incredible degree. 22 Secondly, there is the remarkable fact that human minds, themselves dependent on the whole Universe for their existence, are able to appreciate and understand to some extent the fundamental mathematical structure of the Universe's design. 23 As Albert Einstein commented, 'The most incomprehensible thing about the universe is that it is comprehensible .' In the theory of Gaia, the Earth itself is central and humans are just one part of life on Earth; the insights of cosmology suggest that humans have a particular place in the whole scheme of things.

This section has recognised the intrinsic unity and interdependencies that exist not only on our Earth but also within the whole Universe, and the particular place that we humans have in the Universe. Being aware of these has large implications for our attitude to our environment .

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