gaia hypothesis ppt

ENVS203: Environmental Ethics, Justice, and World Views

The gaia hypothesis.

Read this page, which discusses the Gaia hypothesis. Do you believe that the theory holds weight, and that we could observe some of impacts as outlined in the hypothesis?

This teaching unit begins with a conceptual sketch of the Gaia Hypothesis, followed by a way of thinking about teaching found in John Dewey's philosophy of education that meets the challenge of Gaia in the classroom. There follows an outline of how Dewey unites scientific and moral problem solving for developing social policy which is, in turn, made applicable to solving problems in the environment. These ideas are translated into lesson plans, a course outline to integrate the unit into a course in ecology and biodiversity, and finally, analytical scoring rubrics.

1. The Gaia Hypothesis

Up until the last decade, few had thought of planet earth as in any sense alive. True in ancient Greece, Gaia was worshipped as the Goddess of the earth and pantheistic tribes had comparable deities of the earth that magically controlled their lives. An important step in this direction came from ecology where self-sustaining systems were discovered in which energy flowed and a delicate balance was maintained between all the organisms in the local environment. A meadow, a pond, or a forest were described as ecosystems. The abiotic factors were the inorganic or nonliving entities essential to the biotic factors or community of life that sustained each other – the producers, the consumers, and decomposers. Subseguently, James Lovelock in his Gaia Hypothesis suggests that the entire earth is one large ecosystem, homeostatically controlled. Furthermore, he shows that the environment was both created to meet life's needs as much as it has adapted to the conditions of the environment. Indeed life and the non-living are inseparable entities rather as the mind is to the body (1). It was more correct to say that the earth as a whole is self-sustaining, self-renewing, and self-creating. The earth is a living planet. Since life is sacred and encompasses both the biotic and the abiotic, the term Gaia seemed appropriate for the living earth.

We are used to the adage "think globally and act locally". Gaian thinking is really this idea in the fullest sense of its meaning. It is thinking through policies of management of the earth as a whole and to look at all other problems as subsets of this. It is a cybernetic approach to global village management where the problem is basically humans and culture, not nature. It is recognition that in our rape of mother earth, Gaia may dispose of us in the process of a planetary self-correcting homeostatic mechanism before we get to destroy Gaia.

As James Lovelock points out in 'Ages of Gaia', the central concept in the Gaia Hypothesis is homeostasis in which microbes, plants, soil organisms, and aquatic life play an integrated role. They control the flow of carbon, nitrogen, water, and other elements that go to make up life – with the sun turning the cycles at the homeostatically corrected temperature for life and by life. Life started taking control of the environment with the development of the double-helical nucleotides and these genes have driven the experiment of life with the environment as its encompassing cloak. (2)

The key example worked out by Lovelock was thermostatic control of the earth's surface temperature. He used the 'Daisy World' model as theoretical construct to demonstrate his theory. In simple outline, Gaia Hypothesis attributes the creation of earth's peculiar atmosphere to

(A) the stratospheric Carbon Dioxide blanket. When thick temperatures rise; when thin it cools. The ocean acts as a sink for Carbon Dioxide along with the rocks. Trees and cyanobacteria also absorb the gas and generate moisture. The Carbon Dioxide blanket above the stratosphere also keeps the oceans from evaporating away.

(B) For surface temperature to be around 13 degrees Celcius, the preferred average temperature for planetary life, it is necessary to have a correct mix of atmospheric gases. Air has the correct balance of 79% Nitrogen, 20% Oxygen and 0.003% Carbon Dioxide (all other planets have very high Carbon Dioxide and minimal Nitrogen and Oxygen). The Oxygen content comes from photosynthetic activity, the Nitrogen from decomposers (protists, fungi and bacteria). Oxygen forms ozone in the ionosphere and neutralizes ultraviolet radiation to protect life.

(C) The luminosity of the earth is lower and controlled by forest and vegetation (micro/macroflora) on land and in the oceans. When darker the temperature cools and when light the temperature rises (the Albedo factor). (3)

The gene flow of information that we call life, to an evolving experimentation problem-solving creation and adaptation to the environment, has an exponential history of development. It is Gaia's own self-development leading from the origin of the universe as bare energy leading up to higher levels of awareness. The levels of Gaia may be represented in powers of 10 from 4.5 billion years ago to the present generation born 45 years ago. The boxes are different by x10 to the power of 2 years. In the final box we have the highest level of self-awareness, a level that has the power to destroy Gaia – see the diagram opposite and the graph above it describing another exponential development, the human population explosion. We humans, though having evolved to an unprecedented level of self-awareness, have become a cancerous growth – a part of Gaia that is reproducing itself uncontrollably and fast killing its living host – Gaia.

It is the point of view of this teaching unit that Gaia protection is the fundamental starting point for all problem-solving in the environment. Norman Myers points out in "Atlas of Future Worlds", that protection of Gaia needs to be embedded in international law and all human behavior subjected to such a law (4). All other environmental and human problems pale by comparison. Accepting the axiom of the inviolability of Gaia would also help prioritize and suggest acceptable solutions to environmental problems, many of which are being sidetracked because of lack of agreement about what constitutes environmental moral culpability. The following unit then takes this as its a priori and seeks to involve students in the Gaia principle in any and every environmental problem that concerns them. Before developing the practicalities of such an undertaking, it seems necessary that we rethink our pedagogy to make sure that it is adequate to deal with the holistic mode of thinking required by the Gaia hypothesis, and rethinking John Dewey's educational philosophy is our place to begin.

2. Gaia and Education

John Dewey has had a profound influence on American education. The present reforms in science education are almost pure Deweyan. Those earlier reforms instituted in his name were not as successful as hoped but with research and creativity, the integrity of his ideas have been practically realized. However, the fundamentals of his philosophy of education have far-reaching implications that this unit seeks to include.

The first significant relevance is Dewey's own all-encompassing metaphor that he carried to all his ideas about education i.e. the metaphor of life itself. Life is self-renewing, self-adaptive, systemic, and social; hence education must have these characteristics to be effective.

"The most notable distinction between living things and inanimate things is that the former maintain themselves by renewal".(5) Education is such a process of renewal and transmission of resources that also includes ideas, skills, and so forth for the purpose of continuing life in the environment. Education communicates habits (skills) in doing, thinking, and feeling from generation to generation. The whole range of life's experience is passed on to individuals that enlarges their private experience. The individual 'goes out' of the self to find points of contact with that wider experience, the life of the species. (6)

Education manipulates meanings that have been called for by the need to interact and solve problems, those problems given by history, the present, and the challenge of the future. The ability to respond is natural to us – not an extrinsic capacity to be forced on the unwilling. It is not an act of conditioning but learning to see how ideas come together in a dynamic interplay to achieve some goal. The example Dewey gives to make his point is a baseball game. The game cannot be taught by memorizing rules or sequences of events. These may be used in the process of learning the game, but nothing is learned until the idea of the game is learned. Each of the parts have to come together so that it all makes sense. The test is whether the information works for the individual and they can be creatively used. When this is achieved the individual can demonstrate it and see how all the parts of the game are systemically interconnected to achieve the goal of winning and so forth. In this unit, problems will be thought through in such a 'feedback' loop.

At the heart of education is the idea of growth and this is equally characteristic of life as it moves from inception to death. Dewey's key ideas in this respect are 'reorganizing, reconstructing and transformation'.

Education by contrast is not static and not extrinsic. It is about taking the past into the future with thought, inventiveness and initiative.(7) Gaia problem solving challenges us all to break out of the static 'business as usual' ways of thinking.

The relevance to Gaian thought is that education must be taken out of its abstract and past orientation so as to apply past knowledge to the present and future. We need to move out of the Newtonian universe and move into the contemporary world of nonlinear physics, holistic math, creative chaos, and global cultural dialogue. Education must transcend meeting the interests of the status quo, class (business) privilege, or nationalist self-interest, for the purposes of all life, all of humanity, and for responding creatively to the environment. (8)

As Gaia is sacred and has its own ends and meanings, so also education provides its own interests, its own intrinsic ends. What is intrinsic, however, is open-ended, flexible, responsive, a shared activity, personal, and problem-solving. It is intelligent and springs from the student's own natural intelligence. It is its own discipline.

Dewey does not equate education with mere biological life but with reflective thought within the biological process of living in the environment. The essence of education is thinking within experience. Intelligence is not limited to humans. Humans are more adapted to finding a reflective solution to an environmental problem. Reflective experience or intelligent thought may be summarized as follows and is clearly a generalized scientific way of thinking that can be applied to any kind of experience of any kind.

perplexity, doubt, confusion in a situation (a problem/question) a tentative interpretation (hypothesis, projected answer) a careful detailed survey or examination of the experience (observations to clarify the problem) hypothesis (rational explanation) stated with independent variables (causes) and dependent variables (effects) test the explanation by effecting a cause to produce an effect or in other words, live the thought within an experience to see if it gives integrity or coherence to the event. (9)

Methodology in teaching is then no more nor less than the method of intelligent thinking. Students cannot learn this unless they participate in an event that requires active reflection. It cannot be isolated from the world but part and parcel of an action that becomes part of a growing world of experience. Books bring that accumulation of global experience to the student but it has to become a direct experience to become meaningful. The task of the teacher is to help mediate 'universal' and private experience.

In Dewey's major opus 'Democracy and Education', he elaborates the above in terms of the various disciplines – geography, history, humanities, science, and so forth (10). He also apples it to the social spirit, the essence of morality. In the following teaching unit, we will focus more of the implication of his educational theory to ethics and problem solving, particularly as they relate to environmental crises of Gaian proportions. The relevance of Dewey's pedagogy above will be highlighted too.

3. Developing a Social Policy

From the reasoning above, a teaching methodology will develop out of the steps needed to think intelligently when confronted by some aspect of the environment that we experience or live in. It is essentially scientific but since we are developing social policy we are also operating at a moral level of reasoning. Can such a methodology work for moral reasoning? In my teaching unit on genetics (YNHTI 1996), I set out Dewey's arguments for the appropriateness of scientific reasoning when making ethical judgments. His key justifications are as follows:

Moral judgments, as science, deals with time and space since both concern antecedents and consequences. In both science and morality, universals are abstracted out of particular events and actual contexts. Both concern universal 'laws' that only mean anything as predicators in actual situations. Science and morality both concern judgments on experiences that require reflection and then action to test theoretical understandings. These are tested as events involving some action, the results of which are used to confirm or deny the validity of the prior reflections and judgments. Science demands that reason be subjected to the hard knocks of experience. Similarly morality must justify itself in terms of actual experienced problems. Neither can hide behind appeals to transcendence independent of experience if they are to claim to be true. Both science and morality involve feeling awareness, rational cognition and action to test validity of the relationship between feeling and thought. Feeling awareness in both science and morality is attention to some aspect of the immediacy of experience that calls forth sentient interest, goals and vision of possibilities (in morality, love is an example of this). Cognition consists of logical connections in experience based on cause and effect. Objective thought in morality and science comes from acting out this reasoning within the environment (in morality, moral principles are reasoning within an experience such as love). If the consequences of action meet those expected by reason and those desired by the original feeling awareness (that drew one's attention to this aspect of the environment in the first place) then both science and morality have reasonable grounds for objectivity. Since methodology of making scientific and moral judgments are analogous, then the use of the following scientific or intelligent method of making social policies to solve problems in the environment are legitimated.

To simplify the above, we may use the life-skills problem-solving schema described below that all teachers in New Haven Public Schools are expected to use, where applicable, across all academic disciplines. What follows is a practical application of this applied to the population crisis.

(i) Defining the Problem

a. Population is the root cause of pollution and since population increases exponentially so pollution is increasing exponentially and so necessarily uncontrollably.

b. Pollution of air, water, and soil means loss of available resources for the expanding population.

c. Population drives consumption that depletes resources and prevents a balanced or sustainable economy with the environment. It drives the need for synthetics and the need for garbage disposal that further pollutes and cuts back on available land and resources.

d. Population increase drives the need to use mass farming techniques such as mono-genetic crops and pesticides that only increases productivity of crop production in the short term. It increases the risk of loss of protection from pests in the future and toxicity to life in general. In the process, further environmental damage threatens the existing level of human population.

e. Population increase means reduction of forests to provide fuel and more cultivated land, more houses and recreational space, etc. Loss of forests threatens global homeostatic control of global temperature.

If the temperature goes up there is flooding and increased rate of desertification, if the temperature goes down, there is a movement towards a glacial age. In either case, there is more land lost to farming.

f. Increase in population means increased dependence upon oil and other imported goods that decreases national security and so increases military expenditure that reduces resources available for feeding the population etc

g. Increase in population ultimately threatens all environmental treaties because the struggle for survival will justify governments to abandon them, that then in turn may lead to qualitative leaps in environmental destruction, and as such possibly lead to death of Gaia or devastating loss of human life to levels below existing population.

(ii) Hypothetical Solutions

a) Give tax and social benefits as incentives to 2 children families and penalties for exceeding this number.

b) Require all synthetics to be either biodegradable or able to be recycled on a sustainable basis.

c) Agribusiness must justify all management and farming policies based upon long term sustainable policies, organic solutions to pest and preservation of genetic diversity in the environment.

d) Enforcement of 'greenbelts' around all forest and woodlands. Cutting of trees must not threaten a complex ecosystem in which they live.

e) Reduce dependence upon foreign imports to reduce military expenditure. Reduce foreign debt by limiting profits that can be made on loans.

f) Support an international economic order that requires foreign trade to be based upon the best use of natural resources consistent with local climate or distinctive biome needs.

g) Give priority to all plans that address issues solving systemic problems.

(iii) Determine what criteria would be used to deem plans/solutions as good/bad or better/worse. (controlling variables).

The task is now to anticipate consequences of the hypothetical solutions that have been imagined. In this case, we are interested in:

• outcomes for the government, state or wider community material or nonmaterial.
• outcomes for those immediately involved.
• outcomes for extended family and others directly affected.
• anticipated outcomes based upon research into comparable situations, for example China.
• anticipate costs to different sectors of the economy and ways to deal with this.

(iv) Procedure/Materials/Presentation of Data.

Choose the best hypothetical plan and fully write out how it would be implemented with list of resources and costs incurred. Plan data tables, graphs, and so forth to determine how outcomes can be measured and presented.

(v) Conclusion

Recommend implementing the plan that appears to offer the best outcomes. Point out limitations and expected arrears for refinement.

Saylor Academy Knowledge Check

"The Gaia hypothesis says that the temperature, oxidation state, acidity, and certain aspects of the rocks and waters are kept constant, and that this homeostasis is maintained by active feedback processes operated automatically and unconsciously by the biota." - James Lovelock, The Ages of Gaia

Suggested Readings:

• Margulis, L and J. Lovelock. 1976. Is Mars a Spaceship, Too? Natural History , June/July pp. 86-90

In this lesson, we learn:

• What are the weaknesses of the hypothesis? What are its strengths?
• What are some examples of Gaia-like feedbacks?

Jump to: [ Introduction ] [ Origin of the Hypothesis ] [ Examples of Regulation ] [ Alternatives to Gaia ] [ Many Gain Hypotheses ] [ Summary ]

1. introduction - gaia and global change, 2. the hypothesis and its originators.

3. Examples of Regulation of the Environment, According to Gaia

Perhaps life regulates the physical and chemical environment of the planet so as to maintain suitable planetary conditions for the good of life itself. If so, then the planet can be thought of as a single, integrated, living entity with self-regulating abilities. This is the radical view that Lovelock and Margulis have espoused. It can be thought of as the "strong Gaian model."

4. Alternatives to the Gaia Hypothesis

• The idea that climate and life influence one another is profoundly important. In some form or another, it has been recognized for a long time. Life and climate "grew up together" and influenced one another over most of earth history. But this is not to say that life somehow manages and self-optimizes its own environment. It is this idea -- the "strong form of Gaia" -- that is most controversial.

5. The Many Gaian Hypotheses

"...it is unlikely that chance alone accounts for the fact that temperature, pH and the presence of compounds of nutrient elements have been, for immense periods, just those optimal for surface life. Rather, ... energy is expended by the biota to actively maintain these optima" (Lovelock and Margulis, 1974).

6. Modeling Gaia

You can model feedbacks using the classic Gaia example of Daisyworld with Stella or using this interactive Java applet .  The latter is especially useful to get a first-order understanding of changing parameters.  The Stella model permit more sophisticated analysis.

• The hypothesis has been defined and argued in numerous ways, and has as many critics as adherents. It is in need of more explicit formulation before it can be examined and tested as a true scientific theory.  
• Two models emerge: The model that life influences planetary processes (i.e., it has a substantial effect on abiotic processes) has become known as the weak Gaia hypothesis .  This model is widely supported. The original Gaia hypothesis, that life controls planetary processes (i.e., life created Earth's system), has become known as the strong Gaia hypothesis .  It is not widely accepted.

All materials © the Regents of the University of Michigan unless noted otherwise.

• Preferences

GAIA: The Earth System - PowerPoint PPT Presentation

GAIA: The Earth System

The gaia hypothesis: earth is a self-regulating system ... gaia': the biota optimize climate. for their own benefit (not part of lovelock's definition of gaia) ... – powerpoint ppt presentation.

• Gaia is Mother Earth. She is from whom everything comes, but she is not quite a divinity, because she is Earth. She bore the Titans as well as monsters like the hundred armed men, and some of the Cyclopes - others were sons of Poseidon. She was the daughter of Chaos, and the mother of all creatures (according to some). She was the first and the last, and wanted all of her children, no matter what. She was primarily spoken of as a Mother of other Gods, rather than having her own myths.
• The Gaia Hypothesis
• Earth is a self-regulating system
• The system includes both life and the physical world
• The system is capable of maintaining a surface environment that is suitable for life
• Redwood trees are like Gaia because 97 of their tissues are dead. The wood of the trunk and the bark of the tree are dead. Only a small rim of cells along the periphery of the trunk is living. The trunk of the tree is similar to the Earth's lithosphere with a thin layer of living organisms spread across its surface. The bark, like the atmosphere, protects the living tissues, and allows for the exchange of biologically important gases, such as carbon dioxide and oxygen.
• Three Interpretations of the Gaia Hypothesis
• Theological or teleological
• Earth System is sensitive
• Earth System is resilient
• Theological or Teleological View
• Earth controls its own destiny
• Optimizing Gaia The biota optimize climate
• for their own benefit
• (not part of Lovelocks definition of Gaia)
• View that the Earth System is Sensitive
• The system is interconnected, and a small perturbation can influence the whole system
• Certainly is true with respect to the weather
• The butterfly effect A butterfly flapping its wings in the Amazon can influence weather patterns globally a few days later
• Probably not literally true, but nevertheless this is an illustration of chaos,which is observed in weather simulations
• View that the Earth System is Resilient
• The system can adapt to perturbations
• This should not be interpreted as meaning that we can do anything we like, e.g., emit large amounts of CO2, and nothing will happen as a result...
• Scientific Implications of Gaia Hypothesis
• A new view of the Earth as one system
• Not really that newVernadsky had
• proposed this back in the early part of
• the last century
• From this view emerged Earth System Science

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2.1.4.3: Gaia - Bioregulation of the Environment

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• Stephen Lower
• Simon Fraser University

The Gaia Hypothesis

The physical conditions under which life as we know it can exist encompass a relatively narrow range of temperature, pH, osmotic pressure, and ultraviolet radiation intensity. It seems remarkable enough that life was able to get started at all; it is even more remarkable that it has continued to thrive in the face of all the perils that have, or could have occurred, during the past 3 billion years or so.

During the time that life has been evolving, the sun has also been going through the process of evolution characteristic of a typical star; one consequence of this is an increase in its energy output by about 30 percent during this time. If the sun’s output should suddenly drop to what it was 3 billion years ago, the oceans would freeze. How is it that the earth was not in a frozen state for the first 1.5 billion years of life’s existence? Alternatively, if conditions were somehow suitable 3 billion years ago, why have the oceans not long since boiled away?

A rather non-traditional answer to this kind of question is that the biosphere is far from playing a passive role in which it is continually at the mercy of environmental conditions. Instead, the earth’s atmosphere, and to a lesser extent the hydrosphere, may be actively maintained and regulated by the biosphere. This view has been championed by the British geochemist J.E. Lovelock, and is known as the Gaia hypothesis .

Gaia is another name for the Greek earth-goddess Ge , from which root the sciences of geography, geometry, and geology derive their names. Lovelock's book Gaia: a new look at life on Earth (Oxford, 1979) is a short and highly readable discussion of the hypothesis.

Evidence in support of this hypothesis is entirely circumstantial, but nevertheless points to important questions that must be answered: how have the climatic and chemical conditions on the earth remained optimal for life during all this time; how can the chemical composition of the atmosphere remain in a state that is tens of orders of magnitude from equilibrium?

Although the Gaia hypothesis has received considerable publicity in the popular press, it has never been very well received by the scientific community, many of whom feel that there is no justification for proposing a special hypothesis to describe a set of connections which can be quite adequately explained by conventional geochemical processes. More recently, even Lovelock has backed away from the teleological interpretation of these relations, so that the Gaia hypothesis should now be more properly described as a set of loosely connected effects, rather than as a hypothesis. Nevertheless, these effects and the mechanisms that might act to connect them are sufficiently interesting that it seems worthwhile to provide an overview of the major observations that led to the development of the hypothesis.

Teleology is the doctrine that natural processes operate with a purpose. See No longer willful, Gaia becomes respectable. 1988: Science 240 393-395.

Bioregulation of the Atmosphere

The increase in the oxygen content of the atmosphere as a result of the development of the eucaryotic cell was discussed above. Why has the oxygen content leveled off at 21 percent? It is interesting to note that if the oxygen concentration in the atmosphere were only four percent higher, even damp vegetation, once ignited by lightning, would continue to burn, enveloping vast areas of the earth in a firestorm. Evidence for such a worldwide firestorm that may be related to the extinction of the dinosaurs has recently been discovered. The charcoal layers found in widely distributed sediments laid down about 65 million years ago are coincident with the iridium anomaly believed to be due to the collision of a large meteor with the earth.

• Oxygen : Regulation of the oxygen partial pressure is probably achieved by a balance between its production through photosynthesis and its consumption during oxidation of organic matter; the present steady state requires the burial of about 0.1% the carbon that is fixed annually, leaving one O 2 molecule in the air for each atom of carbon removed from the photosynthetic cycle. The large quantities of microbially-produced methane and N 2 O also constitute important oxygen sinks; if methanogenic bacteria should suddenly cease to exist, the O 2 concentration would rise by 1% in about 12,000 years. This type of regulation implies a negative feedback mechanism, in which an increase in atmospheric oxygen would increase the activity of organisms capable of generating metabolic products that react with it.
• Nitrous oxide : Nitrous oxide, in addition to serving as an oxygen sink, might also be a factor in the regulation of the intensity of the ultraviolet component of sunlight. N 2 O acts as a catalytic intermediate in the decomposition of stratospheric ozone, which shields the earth from excessive ultraviolet radiation.
• Ammonia : Ammonia, another atmospheric gas, is produced by the biosphere in approximately the same quantities as methane, 10 9 tons per year, and at the expense of a considerable amount of metabolic energy. The function of NH 3 could well be to regulate the pH of the environment; in the absence of ammonia, the large amounts of SO 2 and HCl produced by volcanic action would reduce the pH of rain to about 3. The fact that the atmospheric concentration of ammonia is only 10 –8 times that of N 2 should not imply that this “trace” component plays a less significant role in the overall nitrogen cycle than does than N 2 . In fact, the annual rates of production of the two gases are roughly the same; the much lower steady-state concentration of NH 3 is due to its faster turnover time.
• Nitrogen : As stable as the triply-bonded N 2 molecule is, there is a still more stable form of nitrogen: the hydrated nitrate ion. How is this stability consistent with the predominance of nitrogen in the atmosphere? The answer is that it is not: if it were not for nitrogen-fixing bacteria (powered directly or indirectly by the free energy of ATP captured from sunlight), the nitrogen content of the atmosphere would disappear to almost zero. This would raise the oxygen fraction to disastrously high levels, and the additional NO 3 – concentration would increase the ionic strength and osmotic pressure of seawater to levels inconsistent with most forms of life.

Bioregulation of the Oceans

The input of salts into the sea from streams and rivers is about 5.4 x 10 8 tons per year, into a total volume of about 1.2 x 10 9 km 3 yr –1 . Upwelling of juvenile water and hydrothermal action at oceanic ridges provide additional inputs of salts. With a few bizarre exceptions such as the brine shrimp and halophilic bacteria, 6 percent is about the maximum salinity level that organisms can tolerate. The internal salinities of cells must be maintained at much lower levels (around 1%) to prevent denaturation of proteins and other macromolecules whose conformations are dependent on electrostatic forces. At higher levels than this, the electrostatic interaction between the salt ions and the cell membrane destroys the integrity of the latter so that it can no longer pump out salt ions that leak in along the osmotic gradient. At the present rate of salt input, the oceans would have reached their present levels of salinity millions of years ago, and would by now have an ionic strength far to high to support life, as is presently the case in the landlocked Dead Sea.

The present average salinity of seawater is 3.4 percent. The salinity of blood, and of many other intra- and intercellular fluids in animals, is about 0.8 percent. If we assume that the first organisms were approximately in osmotic equilibrium with seawater, then our body fluids might represent “fossilized” seawater as it existed at the time our predecessors moved out of the sea and onto the land.

By what processes is salt removed from the oceans in order to maintain a steady-state salinity? This remains one of the major open questions of chemical oceanography. There are a number of answers, mostly based on strictly inorganic processes, but none is adequately supported by available evidence. For example, Na + and Mg 2 + ions could adsorb to particulate debris as it drops to the seafloor, and become incorporated into sediments. The requirement for charge conservation might be met by the involvement of negatively charged silicate and hydroxyaluminum ions. Another possible mechanism might be the burial of salt beds formed by evaporation in shallow, isolated arms of the sea, such as the Persian Gulf. Extensive underground salt deposits are certainly found on most continents, but it is difficult to see how this very slow mechanism could have led to an unfluctuating salinity over shorter periods of highly variable climatic conditions.

The possibility of biological control of oceanic salinity starts with the observation that about half of the earth’s biomass resides in the sea, and that a significant fraction of this consists of diatoms and other organisms that build skeletons of silica. When these organism die, they sink to the bottom of the sea and add about 300 million tons of silica to sedimentary rocks annually. It is for this reason that the upper levels of the sea are undersaturated in silica, and that the ratio of silica to salt in dead salt lakes is much higher than in the ocean.

These facts could constitute a basis for a biological control of the silica content of seawater; any link between silica and salt could lead to the control of the latter substance as well. For example, the salt ions might adsorb onto the silica skeletons, and be carried down with them; if the growth of these silica-containing organisms is itself dependent on salinity, we would have our negative feedback mechanism.

The continual buildup of biogenic sedimentary deposits on the ocean floor might possibly deform the thin oceanic crust by its weight, and cause local heating by its insulating properties. This could conceivably lead to volcanic action and the formation of new land mass, thus linking the lithosphere into Gaia.

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Stephen Lower, Professor Emeritus ( Simon Fraser U. ) Chem1 Virtual Textbook

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GAIA HYPOTHESIS the idea of the Earth as a single living superorganism

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The GAIA Hypothesis and it‘s role in Earth System Modelling

Sep 04, 2014

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The GAIA Hypothesis and it‘s role in Earth System Modelling. The release of this image had an effect in leading to the proposition that the Earth is alive. Quelle: Wikipedia. GCM – 1. Semester: Physical Fundamentals of GC, Juliane Gnau.

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The GAIA Hypothesis and it‘s role in Earth System Modelling The release of this image had an effect in leading to the proposition that the Earth is alive. Quelle: Wikipedia GCM – 1. Semester: Physical Fundamentals of GC, Juliane Gnau

The GAIA Hypothesis and it‘s role in Earth System Modelling Content • Earth System Science • Earth System Modelling • The GAIA Hypothesis • Recent research • “Official proof of acceptance”

Earth System Science •  … treats the entire Earth as a system • this system evolves as a result of positive and negative feedbacks between many different systems • gives scientists the ability to explain the past and possible future behaviour of the Earth system ms: See the comlete version of the so-called Bretherton Diagram(Francis P. Bretherton, 1986)

What is Earth System Modelling? Interacting components on the environment are modeled in unison to understand how feedbacks between the components influence the properties of the whole system. Quelle: Max-Planck-Institut Gaia theories explain the behaviour of the Earth system in terms of the influence of the biosphere

Development of Earth System Modelling Quelle: Max-Planck-Institut, verändert ms: That is only half the truth. It shows only the natural systems approach to climate modelling. The whole Earth System Modelling would comprise the socio-economic modelling as well, like: world economic system, national and international institutions and actors, ….

Goals of Earth System Modelling • to predict the future of the planet Earth • instrument to take appropriate actions in the future within the framework of future management of the Earth

The GAIA Hypothesis James Lovelock‘s definition: a complex entity involving the Earth's biosphere, atmosphere, oceans, and soil; the totality constituting a feedback or cybernetic system which seeks an optimal physical and chemical environment for life on this planet

The Initial Hypothesis • biomass modifies conditions on planet • hospitality = homeostasis • homeostatic feedback system • operated by the biota • leads to stabilization of global temperature and chemical composition Global control system: • surface temperature • atmospheric composition • ocean salinity

The Development of the Hypothesis • 1960: Ecological theory: the Earth as an organism • Core assumption of hypothesis: „Lives of a cell“ • Scientifically formulated by J. Lovelock • Supported by scientific experiments • + providing useful predictions  Theory • 1972: "Gaia as seen through the atmosphere" • Until 1975 almost totally ignored • 1979: book “Gaia: A new look at life on Earth”

The Development of the Hypothesis • Acception took many years • 1980’s: still confusion what the GAIA theory really is • Criticism: • view is too theological • lack of scientific evidence • GAIA is not a living organism History

The Development of the Hypothesis • response to criticism = math. Daisyworld  • proof for existance of feedback mechanisms • Lovelock‘s reframing as geophysiology • growing acceptance of Earth System Science •  silenced many critics History

Recent developments • Gaia Theory has developed considerably • 1998 book: “The Symbiotic Planet”(L. Margulis) •  "Gaia is not an organism", but "an emergent property of interaction among organisms". • New definition: “…the series of interacting ecosystems that compose a single huge ecosystem at the Earth's surface.“ • both theories are valid today

The GAIA Hypothesis • two GAIA Conferences • 1988: the Gaian teological views or "types" of Gaia Theory • 2000: specific mechanisms: Recent developments • has Gaia changed in time? • how can the feedbacks influence the climate? • how can mechanisms be modeled?

The GAIA Hypothesis - Summary • the Gaia hypothesis ismodified • biosphere = ecosystem • the Gaia hypothesis is consistent with a modern vision of global ecology, relaying on the concepts of biosphere and biodiversity  • not a theory anymore (?) • part of Earth System Science • scientific model in geo-biosphere • non-scientists: self-regulating Earth Today ms: In common usage, people often use the word theory to signify a conjecture, an opinion, or a speculation. In science however, a theory is a proposed description, explanation, or model of the manner of interaction of a set of natural phenomena, capable of predicting future occurrences or observations!

The GAIA Hypothesis • modelling real biochemical cycles of Earth  • Daisyworld-like regulation • today: simple feedback mechanisms accepted •  carbon dioxide • more difficult homeostatic mechanisms ? •  planetary albedo More recent research

“Official proof of acceptance“ • Amsterdam declaration of the scientific communities of 4 international global change research programmes: • threat of significant climate change • increasing human modification of global environment • findings and statements seem to be fully consistent with the Gaia theory More recent research The Earth System behaves as a single, self-regulating system comprised of physical, chemical, biological and human components.

“Official proof of acceptance“ “The interactions and feedbacks between the component parts are complex and exhibit multi-scale temporal and spatial variability.” “Global change cannot be understood in terms of a simple cause-effect paradigm. Human-driven changes cause multiple effects that cascade through the Earth System in complex ways.” More recent research “These effects interact with each other and with local- and regional-scale changes in multidimensional patterns that are difficult to understand and even more difficult to predict.”

The GAIA Hypothesis and it‘s role in Earth System Modelling Thank you for listening ms:Richard Mabey reviews The revenge of Gaia by James Lovelock: “After Hurricane Katrina, a black Gaian joke went the rounds, couched in White House newspeak: Successful mission against the Gulf of Mexico oilfields. Some collateral damage in New Orleans.” • Sources: • Wikipedia • Max-Planck-Institut • http://serc.carleton.edu/introgeo/earthsystem/nutshell/index.html

Comments for Juliane Gnau from Manfred Stock • To be finished .....

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