text:
Gaia hypothesis
From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Hypothesis that living organisms interact with their surroundings in a self-regulating system
The study of planetary habitability is partly based upon extrapolation from knowledge of the Earth's conditions, as the Earth is the only planet currently known to harbour life.
The Gaia hypothesis (/ˈɡaɪ.ə/ GHY-ə, /ˈɡeɪ.ə/ GAY-ə), also known as the Gaia theory or the Gaia principle, proposes that living organisms interact with their inorganic surroundings on Earth to form a synergistic and self-regulating, complex system that helps to maintain and perpetuate the conditions for life on the planet.
The hypothesis was formulated by the chemist James Lovelock[1] and co-developed by the microbiologist Lynn Margulis in the 1970s.[2] Lovelock named the idea after Gaia, the primordial goddess who personified the Earth in Greek mythology. In 2006, the Geological Society of London awarded Lovelock the Wollaston Medal in part for his work on the Gaia hypothesis.[3]
Topics related to the hypothesis include how the biosphere and the evolution of organisms affect the stability of global temperature, salinity of seawater, atmospheric oxygen levels, the maintenance of a hydrosphere of liquid water and other environmental variables that affect the habitability of Earth.
The Gaia hypothesis was initially criticized for being teleological and against the principles of natural selection, but later refinements aligned the Gaia hypothesis with ideas from fields such as Earth system science, biogeochemistry and systems ecology.[4][5][6] Lovelock also once described the "geophysiology" of the Earth.[7][further explanation needed] Even so, the Gaia hypothesis continues to attract criticism, and today some scientists consider it to be only weakly supported by, or at odds with, the available evidence.[8][9][10]
Contents
1 Overview
2 Details
2.1 Regulation of global surface temperature
2.1.1 Daisyworld simulations
2.2 Regulation of oceanic salinity
2.3 Regulation of oxygen in the atmosphere
2.4 Processing of CO2
3 History
3.1 Precedents
3.2 Formulation of the hypothesis
3.3 First Gaia conference
3.4 Second Gaia conference
3.5 Third Gaia conference
3.6 Fourth Gaia conference
4 Criticism
4.1 Natural selection and evolution
4.2 Criticism in the 21st century
5 See also
6 References
7 Sources
8 Further reading
9 External links
Overview[edit]
Gaian hypotheses suggest that organisms co-evolve with their environment: that is, they "influence their abiotic environment, and that environment in turn influences the biota by Darwinian process". Lovelock (1995) gave evidence of this in his second book, showing the evolution from the world of the early thermo-acido-philic and methanogenic bacteria towards the oxygen-enriched atmosphere today that supports more complex life.
A reduced version of the hypothesis has been called "influential Gaia"[11] in "Directed Evolution of the Biosphere: Biogeochemical Selection or Gaia?" by Andrei G. Lapenis, which states the biota influence certain aspects of the abiotic world, e.g. temperature and atmosphere. This is not the work of an individual but a collective of Russian scientific research that was combined into this peer reviewed publication. It states the coevolution of life and the environment through “micro–forces”[11] and biogeochemical processes. An example is how the activity of photosynthetic bacteria during Precambrian times have completely modified the Earth atmosphere to turn it aerobic, and as such supporting evolution of life (in particular eukaryotic life).
Since barriers existed throughout the Twentieth Century between Russia and the rest of the world, it is only relatively recently that the early Russian scientists who introduced concepts overlapping the Gaia hypothesis have become better known to the Western scientific community.[11] These scientists include:
Piotr Alekseevich Kropotkin (1842–1921)
Rafail Vasil’evich Rizpolozhensky (1847–1918)
Vladimir Ivanovich Vernadsky (1863–1945)
Vladimir Alexandrovich Kostitzin (1886–1963)
Biologists and Earth scientists usually view the factors that stabilize the characteristics of a period as an undirected emergent property or entelechy of the system; as each individual species pursues its own self-interest, for example, their combined actions may have counterbalancing effects on environmental change. Opponents of this view sometimes reference examples of events that resulted in dramatic change rather than stable equilibrium, such as the conversion of the Earth's atmosphere from a reducing environment to an oxygen-rich one at the end of the Archaean and the beginning of the Proterozoic periods.
Less accepted versions of the hypothesis claim that changes in the biosphere are brought about through the coordination of living organisms and maintain those conditions through homeostasis. In some versions of Gaia philosophy, all lifeforms are considered part of one single living planetary being called Gaia. In this view, the atmosphere, the seas and the terrestrial crust would be results of interventions carried out by Gaia through the coevolving diversity of living organisms.
The Gaia hypothesis was an influence on the deep ecology movement.[12]
Details[edit]
The Gaia hypothesis posits that the Earth is a self-regulating complex system involving the biosphere, the atmosphere, the hydrospheres and the pedosphere, tightly coupled as an evolving system. The hypothesis contends that this system as a whole, called Gaia, seeks a physical and chemical environment optimal for contemporary life.[13]
Gaia evolves through a cybernetic feedback system operated unconsciously by the biota, leading to broad stabilization of the conditions of habitability in a full homeostasis. Many processes in the Earth's surface essential for the conditions of life depend on the interaction of living forms, especially microorganisms, with inorganic elements. These processes establish a global control system that regulates Earth's surface temperature, atmosphere composition and ocean salinity, powered by the global thermodynamic disequilibrium state of the Earth system.[14]
The existence of a planetary homeostasis influenced by living forms had been observed previously in the field of biogeochemistry, and it is being investigated also in other fields like Earth system science. The originality of the Gaia hypothesis relies on the assessment that such homeostatic balance is actively pursued with the goal of keeping the optimal conditions for life, even when terrestrial or external events menace them.[15]
Regulation of global surface temperature[edit]
Rob Rohde's palaeotemperature graphs
See also: Paleoclimatology
Since life started on Earth, the energy provided by the Sun has increased by 25% to 30%;[16] however, the surface temperature of the planet has remained within the levels of habitability, reaching quite regular low and high margins. Lovelock has also hypothesised that methanogens produced elevated levels of methane in the early atmosphere, giving a view similar to that found in petrochemical smog, similar in some respects to the atmosphere on Titan.[7] This, he suggests tended to screen out ultraviolet until the formation of the ozone screen, maintaining a degree of homeostasis. However, the Snowball Earth[17] research has suggested that "oxygen shocks" and reduced methane levels led, during the Huronian, Sturtian and Marinoan/Varanger Ice Ages, to a world that very nearly became a solid "snowball". These epochs are evidence against the ability of the pre Phanerozoic biosphere to fully self-regulate.
Processing of the greenhouse gas CO2, explained below, plays a critical role in the maintenance of the Earth temperature within the limits of habitability.
The CLAW hypothesis, inspired by the Gaia hypothesis, proposes a feedback loop that operates between ocean ecosystems and the Earth's climate.[18] The hypothesis specifically proposes that particular phytoplankton that produce dimethyl sulfide are responsive to variations in climate forcing, and that these responses lead to a negative feedback loop that acts to stabilise the temperature of the Earth's atmosphere.
Currently the increase in human population and the environmental impact of their activities, such as the multiplication of greenhouse gases may cause negative feedbacks in the environment to become positive feedback. Lovelock has stated that this could bring an extremely accelerated global warming,[19] but he has since stated the effects will likely occur more slowly.[20]
Daisyworld simulations[edit]
Plots from a standard black & white Daisyworld simulation
Main article: Daisyworld
James Lovelock and Andrew Watson developed the mathematical model Daisyworld, in which temperature regulation arises from a simple ecosystem consisting of two species whose activity varies in response to the planet's environment. The model demonstrates that beneficial feedback mechanisms can emerge in this "toy world" containing only self-interested organisms rather than through classic group selection mechanisms.[21]
Daisyworld examines the energy budget of a planet populated by two different types of plants, black daisies and white daisies. The colour of the daisies influences the albedo of the planet such that black daisies absorb light and warm the planet, while white daisies reflect light and cool the planet. As the model runs the output of the "sun" increases, meaning that the surface temperature of an uninhabited "gray" planet will steadily rise. In contrast, on Daisyworld competition between the daisies (based on temperature-effects on growth rates) leads to a shifting balance of daisy populations that tends to favour a planetary temperature close to the optimum for daisy growth.
It has been suggested that the results were predictable because Lovelock and Watson selected examples that produced the responses they desired.[22]
Regulation of oceanic salinity[edit]
Ocean salinity has been constant at about 3.5% for a very long time.[23] Salinity stability in oceanic environments is important as most cells require a rather constant salinity and do not generally tolerate values above 5%. The constant ocean salinity was a long-standing mystery, because no process counterbalancing the salt influx from rivers was known. Recently it was suggested[24] that salinity may also be strongly influenced by seawater circulation through hot basaltic rocks, and emerging as hot water vents on mid-ocean ridges. However, the composition of seawater is far from equilibrium, and it is difficult to explain this fact without the influence of organic processes. One suggested explanation lies in the formation of salt plains throughout Earth's history. It is hypothesized that these are created by bacterial colonies that fix ions and heavy metals during their life processes.[23]
In the biogeochemical processes of the earth, sources and sinks are the movement of elements. The composition of salt ions within our oceans and seas are: sodium (Na+), chlorine (Cl−), sulfate (SO42−), Magnesium (Mg2+), calcium (Ca2+) and potassium (K+). The elements that comprise salinity do not readily change and are a conservative property of seawater.[23] There are many mechanisms that change salinity from a particulate form to a dissolved form and back. The known sources of sodium i.e. salts is when weathering, erosion, and dissolution of rocks transport into rivers and deposit into the oceans.
The Mediterranean Sea as being Gaia's kidney is found (here) by Kenneth J. Hsue a correspondence author in 2001. The "desiccation" of the Mediterranean is the evidence of a functioning kidney. Earlier "kidney functions" were performed during the "deposition of the Cretaceous (South Atlantic), Jurassic (Gulf of Mexico), Permo-Triassic (Europe), Devonian (Canada), Cambrian/Precambrian (Gondwana) saline giants."[25]
Regulation of oxygen in the atmosphere[edit]
Levels of gases in the atmosphere in 420,000 years of ice core data from Vostok, Antarctica research station. Current period is at the left.
See also: Geological history of oxygen
The Gaia hypothesis states that the Earth's atmospheric composition is kept at a dynamically steady state by the presence of life.[26] The atmospheric composition provides the conditions that contemporary life has adapted to. All the atmospheric gases other than noble gases present in the atmosphere are either made by organisms or processed by them.
The stability of the atmosphere in Earth is not a consequence of chemical equilibrium. Oxygen is a reactive compound, and should eventually combine with gases and minerals of the Earth's atmosphere and crust. Oxygen only began to persist in the atmosphere in small quantities about 50 million years before the start of the Great Oxygenation Event.[27] Since the start of the Cambrian period, atmospheric oxygen concentrations have fluctuated between 15% and 35% of atmospheric volume.[28] Traces of methane (at an amount of 100,000 tonnes produced per year)[29] should not exist, as methane is combustible in an oxygen atmosphere.
Dry air in the atmosphere of Earth contains roughly (by volume) 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases including methane. Lovelock originally speculated that concentrations of oxygen above about 25% would increase the frequency of wildfires and conflagration of forests. Recent work on the findings of fire-caused charcoal in Carboniferous and Cretaceous coal measures, in geologic periods when O2 did exceed 25%, has supported Lovelock's contention.[citation needed]
Processing of CO2[edit]
See also: Carbon cycle
Gaia scientists see the participation of living organisms in the carbon cycle as one of the complex processes that maintain conditions suitable for life. The only significant natural source of atmospheric carbon dioxide (CO2) is volcanic activity, while the only significant removal is through the precipitation of carbonate rocks.[30] Carbon precipitation, solution and fixation are influenced by the bacteria and plant roots in soils, where they improve gaseous circulation, or in coral reefs, where calcium carbonate is deposited as a solid on the sea floor. Calcium carbonate is used by living organisms to manufacture carbonaceous tests and shells. Once dead, the living organisms' shells fall to the bottom of the oceans where they generate deposits of chalk and limestone.
One of these organisms is Emiliania huxleyi, an abundant coccolithophore algae which also has a role in the formation of clouds.[31] CO2 excess is compensated by an increase of coccolithophoride life, increasing the amount of CO2 locked in the ocean floor. Coccolithophorides increase the cloud cover, hence control the surface temperature, help cool the whole planet and favor precipitations necessary for terrestrial plants.[citation needed] Lately the atmospheric CO2 concentration has increased and there is some evidence that concentrations of ocean algal blooms are also increasing.[32]
Lichen and other organisms accelerate the weathering of rocks in the surface, while the decomposition of rocks also happens faster in the soil, thanks to the activity of roots, fungi, bacteria and subterranean animals. The flow of carbon dioxide from the atmosphere to the soil is therefore regulated with the help of living beings. When CO2 levels rise in the atmosphere the temperature increases and plants grow. This growth brings higher consumption of CO2 by the plants, who process it into the soil, removing it from the atmosphere.
History[edit]
Precedents[edit]
Earthrise taken from Apollo 8 on December 24, 1968
The idea of the Earth as an integrated whole, a living being, has a long tradition. The mythical Gaia was the primal Greek goddess personifying the Earth, the Greek version of "Mother Nature" (from Ge = Earth, and Aia = PIE grandmother), or the Earth Mother. James Lovelock gave this name to his hypothesis after a suggestion from the novelist William Golding, who was living in the same village as Lovelock at the time (Bowerchalke, Wiltshire, UK). Golding's advice was based on Gea, an alternative spelling for the name of the Greek goddess, which is used as prefix in geology, geophysics and geochemistry.[33] Golding later made reference to Gaia in his Nobel prize acceptance speech.
In the eighteenth century, as geology consolidated as a modern science, James Hutton maintained that geological and biological processes are interlinked.[34] Later, the naturalist and explorer Alexander von Humboldt recognized the coevolution of living organisms, climate, and Earth's crust.[34] In the twentieth century, Vladimir Vernadsky formulated a theory of Earth's development that is now one of the foundations of ecology. Vernadsky was a Ukrainian geochemist and was one of the first scientists to recognize that the oxygen, nitrogen, and carbon dioxide in the Earth's atmosphere result from biological processes. During the 1920s he published works arguing that living organisms could reshape the planet as surely as any physical force. Vernadsky was a pioneer of the scientific bases for the environmental sciences.[35] His visionary pronouncements were not widely accepted in the West, and some decades later the Gaia hypothesis received the same type of initial resistance from the scientific community.
Also in the turn to the 20th century Aldo Leopold, pioneer in the development of modern environmental ethics and in the movement for wilderness conservation, suggested a living Earth in his biocentric or holistic ethics regarding land.
It is at least not impossible to regard the earth's parts—soil, mountains, rivers, atmosphere etc,—as organs or parts of organs of a coordinated whole, each part with its definite function. And if we could see this whole, as a whole, through a great period of time, we might perceive not only organs with coordinated functions, but possibly also that process of consumption as replacement which in biology we call metabolism, or growth. In such case we would have all the visible attributes of a living thing, which we do not realize to be such because it is too big, and its life processes too slow.
—  Aldo Leopold, Animate Earth.[36]
Another influence for the Gaia hypothesis and the environmental movement in general came as a side effect of the Space Race between the Soviet Union and the United States of America. During the 1960s, the first humans in space could see how the Earth looked as a whole. The photograph Earthrise taken by astronaut William Anders in 1968 during the Apollo 8 mission became, through the Overview Effect an early symbol for the global ecology movement.[37]
Formulation of the hypothesis[edit]
James Lovelock, 2005
Lovelock started defining the idea of a self-regulating Earth controlled by the community of living organisms in September 1965, while working at the Jet Propulsion Laboratory in California on methods of detecting life on Mars.[38][39] The first paper to mention it was Planetary Atmospheres: Compositional and other Changes Associated with the Presence of Life, co-authored with C.E. Giffin.[40] A main concept was that life could be detected in a planetary scale by the chemical composition of the atmosphere. According to the data gathered by the Pic du Midi observatory, planets like Mars or Venus had atmospheres in chemical equilibrium. This difference with the Earth atmosphere was considered to be a proof that there was no life in these planets.
Lovelock formulated the Gaia Hypothesis in journal articles in 1972[1] and 1974,[2] followed by a popularizing 1979 book Gaia: A new look at life on Earth. An article in the New Scientist of February 6, 1975,[41] and a popular book length version of the hypothesis, published in 1979 as The Quest for Gaia, began to attract scientific and critical attention.
Lovelock called it first the Earth feedback hypothesis,[42] and it was a way to explain the fact that combinations of chemicals including oxygen and methane persist in stable concentrations in the atmosphere of the Earth. Lovelock suggested detecting such combinations in other planets' atmospheres as a relatively reliable and cheap way to detect life.
Lynn Margulis
Later, other relationships such as sea creatures producing sulfur and iodine in approximately the same quantities as required by land creatures emerged and helped bolster the hypothesis.[43]
In 1971 microbiologist Dr. Lynn Margulis joined Lovelock in the effort of fleshing out the initial hypothesis into scientifically proven concepts, contributing her knowledge about how microbes affect the atmosphere and the different layers in the surface of the planet.[4] The American biologist had also awakened criticism from the scientific community with her theory on the origin of eukaryotic organelles and her contributions to the endosymbiotic theory, nowadays accepted. Margulis dedicated the last of eight chapters in her book, The Symbiotic Planet, to Gaia. However, she objected to the widespread personification of Gaia and stressed that Gaia is "not an organism", but "an emergent property of interaction among organisms". She defined Gaia as "the series of interacting ecosystems that compose a single huge ecosystem at the Earth's surface. Period". The book's most memorable "slogan" was actually quipped by a student of Margulis': "Gaia is just symbiosis as seen from space".
James Lovelock called his first proposal the Gaia hypothesis but has also used the term Gaia theory. Lovelock states that the initial formulation was based on observation, but still lacked a scientific explanation. The Gaia hypothesis has since been supported by a number of scientific experiments[44] and provided a number of useful predictions.[45] In fact, wider research proved the original hypothesis wrong, in the sense that it is not life alone but the whole Earth system that does the regulating.[13]
First Gaia conference[edit]
In 1985, the first public symposium on the Gaia hypothesis, Is The Earth A Living Organism? was held at University of Massachusetts Amherst, August 1–6.[46] The principal sponsor was the National Audubon Society. Speakers included James Lovelock, George Wald, Mary Catherine Bateson, Lewis Thomas, John Todd, Donald Michael, Christopher Bird, Thomas Berry, David Abram, Michael Cohen, and William Fields. Some 500 people attended.[47]
Second Gaia conference[edit]
In 1988, climatologist Stephen Schneider organised a conference of the American Geophysical Union. The first Chapman Conference on Gaia,[48] was held in San Diego, California on March 7, 1988.
During the "philosophical foundations" session of the conference, David Abram spoke on the influence of metaphor in science, and of the Gaia hypothesis as offering a new and potentially game-changing metaphorics, while James Kirchner criticised the Gaia hypothesis for its imprecision. Kirchner claimed that Lovelock and Margulis had not presented one Gaia hypothesis, but four -
CoEvolutionary Gaia: that life and the environment had evolved in a coupled way. Kirchner claimed that this was already accepted scientifically and was not new.
Homeostatic Gaia: that life maintained the stability of the natural environment, and that this stability enabled life to continue to exist.
Geophysical Gaia: that the Gaia hypothesis generated interest in geophysical cycles and therefore led to interesting new research in terrestrial geophysical dynamics.
Optimising Gaia: that Gaia shaped the planet in a way that made it an optimal environment for life as a whole. Kirchner claimed that this was not testable and therefore was not scientific.
Of Homeostatic Gaia, Kirchner recognised two alternatives. "Weak Gaia" asserted that life tends to make the environment stable for the flourishing of all life. "Strong Gaia" according to Kirchner, asserted that life tends to make the environment stable, to enable the flourishing of all life. Strong Gaia, Kirchner claimed, was untestable and therefore not scientific.[49]
Lovelock and other Gaia-supporting scientists, however, did attempt to disprove the claim that the hypothesis is not scientific because it is impossible to test it by controlled experiment. For example, against the charge that Gaia was teleological, Lovelock and Andrew Watson offered the Daisyworld Model (and its modifications, above) as evidence against most of these criticisms.[21] Lovelock said that the Daisyworld model "demonstrates that self-regulation of the global environment can emerge from competition amongst types of life altering their local environment in different ways".[50]
Lovelock was careful to present a version of the Gaia hypothesis that had no claim that Gaia intentionally or consciously maintained the complex balance in her environment that life needed to survive. It would appear that the claim that Gaia acts "intentionally" was a metaphoric statement in his popular initial book and was not meant to be taken literally. This new statement of the Gaia hypothesis was more acceptable to the scientific community. Most accusations of teleologism ceased, following this conference.
Third Gaia conference[edit]
By the time of the 2nd Chapman Conference on the Gaia Hypothesis, held at Valencia, Spain, on 23 June 2000,[51] the situation had changed significantly. Rather than a discussion of the Gaian teleological views, or "types" of Gaia hypotheses, the focus was upon the specific mechanisms by which basic short term homeostasis was maintained within a framework of significant evolutionary long term structural change.
The major questions were:[52]
"How has the global biogeochemical/climate system called Gaia changed in time? What is its history? Can Gaia maintain stability of the system at one time scale but still undergo vectorial change at longer time scales? How can the geologic record be used to examine these questions?"
"What is the structure of Gaia? Are the feedbacks sufficiently strong to influence the evolution of climate? Are there parts of the system determined pragmatically by whatever disciplinary study is being undertaken at any given time or are there a set of parts that should be taken as most true for understanding Gaia as containing evolving organisms over time? What are the feedbacks among these different parts of the Gaian system, and what does the near closure of matter mean for the structure of Gaia as a global ecosystem and for the productivity of life?"
"How do models of Gaian processes and phenomena relate to reality and how do they help address and understand Gaia? How do results from Daisyworld transfer to the real world? What are the main candidates for "daisies"? Does it matter for Gaia theory whether we find daisies or not? How should we be searching for daisies, and should we intensify the search? How can Gaian mechanisms be investigated using process models or global models of the climate system that include the biota and allow for chemical cycling?"
In 1997, Tyler Volk argued that a Gaian system is almost inevitably produced as a result of an evolution towards far-from-equilibrium homeostatic states that maximise entropy production, and Kleidon (2004) agreed stating: "...homeostatic behavior can emerge from a state of MEP associated with the planetary albedo"; "...the resulting behavior of a biotic Earth at a state of MEP may well lead to near-homeostatic behavior of the Earth system on long time scales, as stated by the Gaia hypothesis". Staley (2002) has similarly proposed "...an alternative form of Gaia theory based on more traditional Darwinian principles... In [this] new approach, environmental regulation is a consequence of population dynamics, not Darwinian selection. The role of selection is to favor organisms that are best adapted to prevailing environmental conditions. However, the environment is not a static backdrop for evolution, but is heavily influenced by the presence of living organisms. The resulting co-evolving dynamical process eventually leads to the convergence of equilibrium and optimal conditions".
Fourth Gaia conference[edit]
A fourth international conference on the Gaia hypothesis, sponsored by the Northern Virginia Regional Park Authority and others, was held in October 2006 at the Arlington, VA campus of George Mason University.[53]
Martin Ogle, Chief Naturalist, for NVRPA, and long-time Gaia hypothesis proponent, organized the event. Lynn Margulis, Distinguished University Professor in the Department of Geosciences, University of Massachusetts-Amherst, and long-time advocate of the Gaia hypothesis, was a keynote speaker. Among many other speakers: Tyler Volk, Co-director of the Program in Earth and Environmental Science at New York University; Dr. Donald Aitken, Principal of Donald Aitken Associates; Dr. Thomas Lovejoy, President of the Heinz Center for Science, Economics and the Environment; Robert Correll, Senior Fellow, Atmospheric Policy Program, American Meteorological Society and noted environmental ethicist, J. Baird Callicott.
This conference approached the Gaia hypothesis as both science and metaphor as a means of understanding how we might begin addressing 21st century issues such as climate change and ongoing environmental destruction.
Criticism[edit]
After initially being largely ignored by most scientists (from 1969 until 1977), thereafter for a period the initial Gaia hypothesis was criticized by a number of scientists, such as Ford Doolittle,[54] Richard Dawkins[55] and Stephen Jay Gould.[48] Lovelock has said that because his hypothesis is named after a Greek goddess, and championed by many non-scientists,[42] the Gaia hypothesis was interpreted as a neo-Pagan religion. Many scientists in particular also criticised the approach taken in his popular book Gaia, a New Look at Life on Earth for being teleological—a belief that things are purposeful and aimed towards a goal. Responding to this critique in 1990, Lovelock stated, "Nowhere in our writings do we express the idea that planetary self-regulation is purposeful, or involves foresight or planning by the biota".
Stephen Jay Gould criticised Gaia as being "a metaphor, not a mechanism."[56] He wanted to know the actual mechanisms by which self-regulating homeostasis was achieved. In his defense of Gaia, David Abram argues that Gould overlooked the fact that "mechanism", itself, is a metaphor — albeit an exceedingly common and often unrecognized metaphor — one which leads us to consider natural and living systems as though they were machines organized and built from outside (rather than as autopoietic or self-organizing phenomena). Mechanical metaphors, according to Abram, lead us to overlook the active or agential quality of living entities, while the organismic metaphorics of the Gaia hypothesis accentuate the active agency of both the biota and the biosphere as a whole.[57][58] With regard to causality in Gaia, Lovelock argues that no single mechanism is responsible, that the connections between the various known mechanisms may never be known, that this is accepted in other fields of biology and ecology as a matter of course, and that specific hostility is reserved for his own hypothesis for other reasons.[59]
Aside from clarifying his language and understanding of what is meant by a life form, Lovelock himself ascribes most of the criticism to a lack of understanding of non-linear mathematics by his critics, and a linearizing form of greedy reductionism in which all events have to be immediately ascribed to specific causes before the fact. He also states that most of his critics are biologists but that his hypothesis includes experiments in fields outside biology, and that some self-regulating phenomena may not be mathematically explainable.[59]
Natural selection and evolution[edit]
Lovelock has suggested that global biological feedback mechanisms could evolve by natural selection, stating that organisms that improve their environment for their survival do better than those that damage their environment. However, in the early 1980s, W. Ford Doolittle and Richard Dawkins separately argued against Gaia. Doolittle argued that nothing in the genome of individual organisms could provide the feedback mechanisms proposed by Lovelock, and therefore the Gaia hypothesis proposed no plausible mechanism and was unscientific.[54] Dawkins meanwhile stated that for organisms to act in concert would require foresight and planning, which is contrary to the current scientific understanding of evolution.[55] Like Doolittle, he also rejected the possibility that feedback loops could stabilize the system.
Lynn Margulis, a microbiologist who collaborated with Lovelock in supporting the Gaia hypothesis, argued in 1999, that "Darwin's grand vision was not wrong, only incomplete. In accentuating the direct competition between individuals for resources as the primary selection mechanism, Darwin (and especially his followers) created the impression that the environment was simply a static arena". She wrote that the composition of the Earth's atmosphere, hydrosphere, and lithosphere are regulated around "set points" as in homeostasis, but those set points change with time.[60]
Evolutionary biologist W. D. Hamilton called the concept of Gaia Copernican, adding that it would take another Newton to explain how Gaian self-regulation takes place through Darwinian natural selection.[33][better source needed]
Criticism in the 21st century[edit]
The Gaia hypothesis continues to be broadly skeptically received by the scientific community. For instance, arguments both for and against it were laid out in the journal Climatic Change in 2002 and 2003. A significant argument raised against it are the many examples where life has had a detrimental or destabilising effect on the environment rather than acting to regulate it.[8][9] Several recent books have criticised the Gaia hypothesis, expressing views ranging from "... the Gaia hypothesis lacks unambiguous observational support and has significant theoretical difficulties"[61] to "Suspended uncomfortably between tainted metaphor, fact, and false science, I prefer to leave Gaia firmly in the background"[10] to "The Gaia hypothesis is supported neither by evolutionary theory nor by the empirical evidence of the geological record".[62] The CLAW hypothesis,[18] initially suggested as a potential example of direct Gaian feedback, has subsequently been found to be less credible as understanding of cloud condensation nuclei has improved.[63] In 2009 the Medea hypothesis was proposed: that life has highly detrimental (biocidal) impacts on planetary conditions, in direct opposition to the Gaia hypothesis.[64]
In a recent book-length evaluation of the Gaia hypothesis considering modern evidence from across the various relevant disciplines the author, Toby Tyrrell, concluded that: "I believe Gaia is a dead end. Its study has, however, generated many new and thought provoking questions. While rejecting Gaia, we can at the same time appreciate Lovelock's originality and breadth of vision, and recognise that his audacious concept has helped to stimulate many new ideas about the Earth, and to champion a holistic approach to studying it".[65] Elsewhere he presents his conclusion "The Gaia hypothesis is not an accurate picture of how our world works".[66] This statement needs to be understood as referring to the "strong" and "moderate" forms of Gaia—that the biota obeys a principle that works to make Earth optimal (strength 5) or favourable for life (strength 4) or that it works as a homeostatic mechanism (strength 3). The latter is the "weakest" form of Gaia that Lovelock has advocated. Tyrrell rejects it. However, he finds that the two weaker forms of Gaia—Coeveolutionary Gaia and Influential Gaia, which assert that there are close links between the evolution of life and the environment and that biology affects the physical and chemical environment—are both credible, but that it is not useful to use the term "Gaia" in this sense.[67]
See also[edit]
Environment portal
Earth sciences portal
Geography portal
Biocoenosis
Earth science
Environmentalism
Gaianism
Holism
Hylozoism
Planetary boundaries
SimEarth
Spiritual ecology
Superorganism
References[edit]
^ Jump up to: a b J. E. Lovelock (1972). "Gaia as seen through the atmosphere". Atmospheric Environment. 6 (8): 579–580. Bibcode:1972AtmEn...6..579L. doi:10.1016/0004-6981(72)90076-5.
^ Jump up to: a b Lovelock, J.E.; Margulis, L. (1974). "Atmospheric homeostasis by and for the biosphere: the Gaia hypothesis". Tellus. Series A. Stockholm: International Meteorological Institute. 26 (1–2): 2–10. Bibcode:1974Tell...26....2L. doi:10.1111/j.2153-3490.1974.tb01946.x. ISSN 1600-0870. Retrieved 20 October 2012.
Jump up ^ "Wollaston Award Lovelock". Retrieved 19 October 2015.
^ Jump up to: a b Turney, Jon (2003). Lovelock and Gaia: Signs of Life. UK: Icon Books. ISBN 1-84046-458-5.
Jump up ^ Schwartzman, David (2002). Life, Temperature, and the Earth: The Self-Organizing Biosphere. Columbia University Press. ISBN 0-231-10213-5.
Jump up ^ Gribbin, John (1990), "Hothouse earth: The greenhouse effect and Gaia" (Weidenfeld & Nicolson)
^ Jump up to: a b Lovelock, James, (1995) "The Ages of Gaia: A Biography of Our Living Earth" (W.W.Norton & Co)
^ Jump up to: a b Kirchner, James W. (2002), "Toward a future for Gaia theory", Climatic Change, 52: 391–408, doi:10.1023/a:1014237331082
^ Jump up to: a b Volk, Tyler (2002), "The Gaia hypothesis: fact, theory, and wishful thinking", Climatic Change, 52: 423–430, doi:10.1023/a:1014218227825
^ Jump up to: a b Beerling, David (2007). The Emerald Planet: How plants changed Earth's history. Oxford: Oxford University Press. ISBN 978-0-19-280602-4.
^ Jump up to: a b c Lapenis, Andrei G. (2002). "Directed Evolution of the Biosphere: Biogeochemical Selection or Gaia?". The Professional Geographer. 54 (3): 379–391 – via [Peer Reviewed Journal].
Jump up ^ David Landis Barnhill, Roger S. Gottlieb (eds.), Deep Ecology and World Religions: New Essays on Sacred Ground, SUNY Press, 2010, p. 32.
^ Jump up to: a b Lovelock, James. The Vanishing Face of Gaia. Basic Books, 2009, p. 255. ISBN 978-0-465-01549-8
Jump up ^ Kleidon, Axel. How does the earth system generate and maintain thermodynamic disequilibrium and what does it imply for the future of the planet?. Article submitted to the Philosophical Transactions of the Royal Society on Thu, 10 Mar 2011
Jump up ^ Lovelock, James. The Vanishing Face of Gaia. Basic Books, 2009, p. 179. ISBN 978-0-465-01549-8
Jump up ^ Owen, T.; Cess, R.D.; Ramanathan, V. (1979). "Earth: An enhanced carbon dioxide greenhouse to compensate for reduced solar luminosity". Nature. 277 (5698): 640–2. Bibcode:1979Natur.277..640O. doi:10.1038/277640a0.
Jump up ^ Hoffman, P.F. 2001. Snowball Earth theory
^ Jump up to: a b Charlson, R. J., Lovelock, J. E, Andreae, M. O. and Warren, S. G. (1987). "Oceanic phytoplankton, atmospheric sulphur, cloud albedo and climate". Nature. 326 (6114): 655–661. Bibcode:1987Natur.326..655C. doi:10.1038/326655a0. CS1 maint: Multiple names: authors list (link)
Jump up ^ Lovelock, James. The Vanishing Face of Gaia. Basic Books, 2009, ISBN 978-0-465-01549-8
Jump up ^ Lovelock J., NBC News. Link Published 23 April 2012, accessed 22 August 2012.[dead link]
^ Jump up to: a b Watson, A.J.; Lovelock, J.E (1983). "Biological homeostasis of the global environment: the parable of Daisyworld". Tellus. 35B (4): 286–9. Bibcode:1983TellB..35..284W. doi:10.1111/j.1600-0889.1983.tb00031.x.
Jump up ^ Kirchner, James W. (2003). "The Gaia Hypothesis: Conjectures and Refutations". Climatic Change. 58 (1–2): 21–45. doi:10.1023/A:1023494111532.
^ Jump up to: a b c Segar, Douglas (2012). The Introduction to Ocean Sciences. http://www.reefimages.com/oceans/SegarOcean3Chap05.pdf: Library of Congress. pp. Chapter 5 3rd Edition. ISBN 978-0-9857859-0-1.
Jump up ^ Gorham, Eville (1 January 1991). "Biogeochemistry: its origins and development". Biogeochemistry. Kluwer Academic. 13 (3): 199–239. doi:10.1007/BF00002942. ISSN 1573-515X. Retrieved 20 October 2012.
Jump up ^ http://www.webviva.com, Justino Martinez. Web Viva 2007. "Scientia Marina: List of Issues". scimar.icm.csic.es. Retrieved 2017-02-04.
Jump up ^ Lovelock, James. The Vanishing Face of Gaia. Basic Books, 2009, p. 163. ISBN 978-0-465-01549-8
Jump up ^ Anbar, A.; Duan, Y.; Lyons, T.; Arnold, G.; Kendall, B.; Creaser, R.; Kaufman, A.; Gordon, G.; Scott, C.; Garvin, J.; Buick, R. (2007). "A whiff of oxygen before the great oxidation event?". Science. 317 (5846): 1903–1906. Bibcode:2007Sci...317.1903A. doi:10.1126/science.1140325. PMID 17901330.
Jump up ^ Berner, R. A. (Sep 1999). "Atmospheric oxygen over Phanerozoic time". Proceedings of the National Academy of Sciences of the United States of America. 96 (20): 10955–10957. Bibcode:1999PNAS...9610955B. doi:10.1073/pnas.96.20.10955. ISSN 0027-8424. PMC 34224. PMID 10500106.
Jump up ^ Cicerone, R.J.; Oremland, R.S. (1988). "Biogeochemical aspects of atmospheric methane" (PDF). Global Biogeochemical Cycles. 2 (4): 299–327. Bibcode:1988GBioC...2..299C. doi:10.1029/GB002i004p00299.
Jump up ^ Karhu, J.A.; Holland, H.D. (1 October 1996). "Carbon isotopes and the rise of atmospheric oxygen". Geology. 24 (10): 867–870. Bibcode:1996Geo....24..867K. doi:10.1130/0091-7613(1996)024<0867:CIATRO>2.3.CO;2.
Jump up ^ Harding, Stephan (2006). Animate Earth. Chelsea Green Publishing. p. 65. ISBN 1-933392-29-0.
Jump up ^ "Interagency Report Says Harmful Algal Blooms Increasing". 12 September 2007. Archived from the original on 9 February 2008.
^ Jump up to: a b Lovelock, James. The Vanishing Face of Gaia. Basic Books, 2009, pp. 195-197. ISBN 978-0-465-01549-8
^ Jump up to: a b Capra, Fritjof (1996). The web of life: a new scientific understanding of living systems. Garden City, N.Y: Anchor Books. p. 23. ISBN 0-385-47675-2.
Jump up ^ S.R. Weart, 2003, The Discovery of Global Warming, Cambridge, Harvard Press
Jump up ^ Harding, Stephan. Animate Earth Science, Intuition and Gaia. Chelsea Green Publishing, 2006, p. 44. ISBN 1-933392-29-0
Jump up ^ 100 Photographs that Changed the World by Life - The Digital Journalist
Jump up ^ Lovelock, J.E. (1965). "A physical basis for life detection experiments". Nature. 207 (7): 568–570. Bibcode:1965Natur.207..568L. doi:10.1038/207568a0. PMID 5883628.
Jump up ^ Geophysiology
Jump up ^ Lovelock, J.E.; Giffin, C.E. (1969). "Planetary Atmospheres: Compositional and other changes associated with the presence of Life". Advances in the Astronautical Sciences. 25: 179–193. ISBN 0-87703-028-6.
Jump up ^ Lovelock, John and Sidney Epton, (February 8, 1975). "The quest for Gaia". New Scientist, p. 304.
^ Jump up to: a b Lovelock, James 2001
Jump up ^ Hamilton, W.D.; Lenton, T.M. (1998). "Spora and Gaia: how microbes fly with their clouds". Ethology Ecology & Evolution. 10 (1): 1–16. doi:10.1080/08927014.1998.9522867. Archived from the original (PDF) on 2011-07-23.
Jump up ^ J. E. Lovelock (1990). "Hands up for the Gaia hypothesis". Nature. 344 (6262): 100–2. Bibcode:1990Natur.344..100L. doi:10.1038/344100a0.
Jump up ^ Volk, Tyler (2003). Gaia's Body: Toward a Physiology of Earth. Cambridge, Massachusetts: MIT Press. ISBN 0-262-72042-6.
Jump up ^ Joseph, Lawrence E. (November 23, 1986). "Britain's Whole Earth Guru". The New York Times Magazine. Retrieved 1 December 2013.
Jump up ^ Bunyard, Peter (1996), "Gaia in Action: Science of the Living Earth" (Floris Books)
^ Jump up to: a b Turney, Jon. "Lovelock and Gaia: Signs of Life" (Revolutions in Science)
Jump up ^ Kirchner, James W. (1989). "The Gaia hypothesis: Can it be tested?". Reviews of Geophysics. 27 (2): 223. Bibcode:1989RvGeo..27..223K. doi:10.1029/RG027i002p00223.
Jump up ^ Lenton, TM; Lovelock, JE (2000). "Daisyworld is Darwinian: Constraints on adaptation are important for planetary self-regulation". Journal of Theoretical Biology. 206 (1): 109–14. doi:10.1006/jtbi.2000.2105. PMID 10968941.
Jump up ^ Simón, Federico (21 June 2000). "GEOLOGÍA Enfoque multidisciplinar La hipótesis Gaia madura en Valencia con los últimos avances científicos". El País (in Spanish). Retrieved 1 December 2013.
Jump up ^ American Geophysical Union. "General Information Chapman Conference on the Gaia Hypothesis University of Valencia Valencia, Spain June 19-23, 2000 (Monday through Friday)". AGU Meetings. Retrieved 7 January 2017.
Jump up ^ Official Site of Arlington County Virginia. "Gaia Theory Conference at George Mason University Law School". Retrieved 1 December 2013.
^ Jump up to: a b Doolittle, W. F. (1981). "Is Nature Really Motherly". The Coevolution Quarterly. Spring: 58–63.
^ Jump up to: a b Dawkins, Richard (1982). The Extended Phenotype: the Long Reach of the Gene. Oxford University Press. ISBN 0-19-286088-7.
Jump up ^ Gould S.J. (June 1997). "Kropotkin was no crackpot". Natural History. 106: 12–21.
Jump up ^ Abram, D. (1988) "The Mechanical and the Organic: On the Impact of Metaphor in Science" in Scientists on Gaia, edited by Stephen Schneider and Penelope Boston, Cambridge, Massachusetts: MIT Press, 1991
Jump up ^ "The Mechanical and the Organic". Archived from the original on February 23, 2012. Retrieved August 27, 2012.
^ Jump up to: a b Lovelock, James (2001), Homage to Gaia: The Life of an Independent Scientist (Oxford University Press)
Jump up ^ Margulis, Lynn. Symbiotic Planet: A New Look At Evolution. Houston: Basic Book 1999
Jump up ^ Waltham, David (2014). Lucky Planet: Why Earth is Exceptional – and What that Means for Life in the Universe. Icon Books. ISBN 9781848316560.
Jump up ^ Cockell, Charles; Corfield, Richard; Dise, Nancy; Edwards, Neil; Harris, Nigel (2008). An Introduction to the Earth-Life System. Cambridge (UK): Cambridge University Press. ISBN 9780521729536.
Jump up ^ Quinn, P.K.; Bates, T.S. (2011), "The case against climate regulation via oceanic phytoplankton sulphur emissions", Nature, 480: 51–56, Bibcode:2011Natur.480...51Q, doi:10.1038/nature10580, PMID 22129724
Jump up ^ Peter Ward (2009), The Medea Hypothesis: Is Life on Earth Ultimately Self-Destructive?, ISBN 0-691-13075-2
Jump up ^ Tyrrell, Toby (2013), On Gaia: A Critical Investigation of the Relationship between Life and Earth, Princeton: Princeton University Press, p. 209, ISBN 9780691121581
Jump up ^ Tyrrell, Toby (26 October 2013), "Gaia: the verdict is…", New Scientist, 220: 30–31, doi:10.1016/s0262-4079(13)62532-4
Jump up ^ Tyrrell, Toby (2013), On Gaia: A Critical Investigation of the Relationship between Life and Earth, Princeton: Princeton University Press, p. 208, ISBN 9780691121581
Sources[edit]
Bondì, Roberto (2006). Blu come un'arancia. Gaia tra mito e scienza. Torino, Utet: Prefazione di Enrico Bellone. ISBN 88-02-07259-0.
Bondì, Roberto (2007). Solo l'atomo ci può salvare. L'ambientalismo nuclearista di James Lovelock. Torino, Utet: Prefazione di Enrico Bellone. ISBN 88-02-07704-5.
Jaworski, Helan (1928). Le Géon ou la Terre vivante. Paris: Librairie Gallimard.
Lovelock, James. The Independent. The Earth is about to catch a morbid fever, 16 January 2006.
Kleidon, Axel (2004). "Beyond Gaia: Thermodynamics of Life and Earth system functioning". Climatic Change. 66 (3): 271–319. doi:10.1023/B:CLIM.0000044616.34867.ec.
Lovelock, James (1995). The Ages of Gaia: A Biography of Our Living Earth. New York: Norton. ISBN 0-393-31239-9.
Lovelock, James (2000). Gaia: A New Look at Life on Earth. Oxford: Oxford University Press. ISBN 0-19-286218-9.
Lovelock, James (2001). Homage to Gaia: The Life of an Independent Scientist. Oxford: Oxford University Press. ISBN 0-19-860429-7.
Lovelock, James (2006), interviewed in How to think about science, CBC Ideas (radio program), broadcast January 3, 2008. Link
Lovelock, James (2007). The Revenge of Gaia: Why the Earth Is Fighting Back — and How We Can Still Save Humanity. Santa Barbara CA: Allen Lane. ISBN 0-7139-9914-4.
Lovelock, James (2009). The Vanishing Face of Gaia: A Final Warning. New York, NY: Basic Books. ISBN 0-465-01549-2.
Margulis, Lynn (1998). Symbiotic Planet: A New Look at Evolution. London: Weidenfeld & Nicolson. ISBN 0-297-81740-X.
Marshall, Alan (2002). The Unity of Nature: Wholeness and Disintegration in Ecology and Science. River Edge, N.J: Imperial College Press. ISBN 1-86094-330-6.
Staley M (September 2002). "Darwinian selection leads to Gaia". J. Theor. Biol. 218 (1): 35–46. doi:10.1006/jtbi.2002.3059. PMID 12297068.
Schneider, Stephen Henry (2004). Scientists debate Gaia: the next century. Cambridge, Massachusetts: MIT Press. ISBN 0-262-19498-8.
Thomas, Lewis G. (1974). The Lives of a Cell; Notes of a Biology Watcher. New York: Viking Press. ISBN 0-670-43442-6.
Further reading[edit]
Joseph, Lawrence E. (1990). Gaia: The Growth of an Idea. New York, N.Y.: St. Martin's Press. ISBN 978-0-31-204318-6.
External links[edit]
D. Abram: The Mechanical and the Organic: on the Impact of Metaphor in Science
D. Abram: The Perceptual Implications of Gaia
Lovelock: 'We can't save the planet' BBC Sci Tech News
Interview: Jasper Gerard meets James Lovelock
Clips of interview with James Lovelock from 2010 at the Wayback Machine (archived 3 March 2016[Timestamp length])
show
v
t
e
Global warming and climate change
show
Temperatures
Brightness temperature
Effective temperature
Geologic record
Hiatus
Historical climatology
Instrumental record
Paleoclimatology
Paleotempestology
Proxy data
Record of the past 1,000 years
Satellite measurements
show
Causes
Anthropogenic
(caused by human activity)
Attribution of recent climate change
Aviation
Biofuel
Black carbon
Carbon dioxide
Deforestation
Earth's energy budget
Earth's radiation balance
Ecocide
Fossil fuel
Global dimming
Global warming potential
Greenhouse effect
(Infrared window)
Greenhouse gases
(Halocarbons)
Land use, land-use change, and forestry
Radiative forcing
Tropospheric ozone
Urban heat island
Natural
Albedo
Bond events
Climate oscillations
Climate sensitivity
Cloud forcing
Cosmic rays
Feedbacks
Glaciation
Global cooling
Milankovitch cycles
Ocean variability
AMO
ENSO
IOD
PDO
Orbital forcing
Solar variation
Volcanism
Models
Global climate model
show
History
History of climate change science
Atmospheric thermodynamics
Svante Arrhenius
James Hansen
Charles David Keeling
show
Opinion and climate change
General
Environmental ethics
Media coverage of climate change
Public opinion on climate change
(Popular culture)
Scientific opinion on climate change
Scientists who disagree with the mainstream assessment
Climate change denial
Global warming conspiracy theory
By country & region
Africa
Arctic
Argentina
Australia
Bangladesh
Belgium
Canada
China
Europe
European Union
Finland
Grenada
Japan
Luxembourg
New Zealand
Norway
Russia
Scotland
South Korea
Sweden
Tuvalu
United Kingdom
United States
show
Politics
Clean Power Plan
Climate change denial
(Manufactured controversy)
Intergovernmental Panel on Climate Change (IPCC)
March for Science
People's Climate March
United Nations Framework Convention on Climate Change (UNFCCC / FCCC)
Global climate regime
show
Potential effects and issues
General
Abrupt climate change
Anoxic event
Arctic dipole anomaly
Arctic haze
Arctic methane emissions
Climate change and agriculture
Climate change and ecosystems
Climate change and gender
Climate change and poverty
Drought
Economics of global warming
Effects on plant biodiversity
Effects on health
Effects on humans
Effects on marine mammals
Environmental migrant
Extinction risk from global warming
Fisheries and climate change
Forest dieback
Industry and society
Iris hypothesis
Megadrought
Ocean acidification
Ozone depletion
Physical impacts
Polar stratospheric cloud
Regime shift
Retreat of glaciers since 1850
Runaway climate change
Sea level rise
Season creep
Shutdown of thermohaline circulation
By country
Australia
South Asia
India
Nepal
United States
show
Mitigation
Kyoto Protocol
Clean Development Mechanism
Joint Implementation
Bali Road Map
2009 United Nations Climate Change Conference
Governmental
European Climate Change Programme
G8 Climate Change Roundtable
United Kingdom Climate Change Programme
Paris Agreement
United States withdrawal
Regional climate change initiatives in the United States
List of climate change initiatives
Emissions reduction
Carbon credit
Carbon-neutral fuel
Carbon offset
Carbon tax
Emissions trading
Fossil fuel phase-out
Carbon-free energy
Carbon capture and storage
Efficient energy use
Low-carbon economy
Nuclear power
Renewable energy
Personal
Individual action on climate change
Simple living
Other
Carbon dioxide removal
Carbon sink
Climate action
Climate Action Plan
Climate change mitigation scenarios
Climate engineering
Individual and political action on climate change
Reducing emissions from deforestation and forest degradation
Reforestation
Urban reforestation
show
Proposed adaptations
Strategies
Damming glacial lakes
Desalination
Drought tolerance
Irrigation investment
Rainwater storage
Sustainable development
Weather modification
Programmes
Avoiding dangerous climate change
Land allocation decision support system
Glossary
Index
Climate change
Global warming
Portal
Retrieved from "https://en.wikipedia.org/w/index.php?title=Gaia_hypothesis&oldid=866519378"
Categories:
Cybernetics
Climate change science
Ecological theories
Superorganisms
Climate feedbacks
1965 introductions
Biogeochemistry
Earth
Biological hypotheses
Astronomical hypotheses
Hidden categories:
CS1 maint: Multiple names: authors list
All articles with dead external links
Articles with dead external links from May 2017
CS1 Spanish-language sources (es)
Articles with short description
Wikipedia articles needing clarification from December 2017
All articles with unsourced statements
Articles with unsourced statements from June 2012
Articles with unsourced statements from July 2015
All articles lacking reliable references
Articles lacking reliable references from September 2012
Webarchive template wayback links
Webarchive template warnings
Navigation menu
Personal tools
Not logged in
Talk
Contributions
Create account
Log in
Namespaces
Article
Talk
Variants
Views
Read
Edit
View history
More
Search
Navigation
Main page
Contents
Featured content
Current events
Random article
Donate to Wikipedia
Wikipedia store
Interaction
Help
About Wikipedia
Community portal
Recent changes
Contact page
Tools
What links here
Related changes
Upload file
Special pages
Permanent link
Page information
Wikidata item
Cite this page
Print/export
Create a book
Download as PDF
Printable version
In other projects
Wikimedia Commons
Languages
Afrikaans
العربية
বাংলা
Català
Čeština
Dansk
Deutsch
Eesti
Ελληνικά
Español
Esperanto
Euskara
فارسی
Français
Gaeilge
Galego
한국어
Bahasa Indonesia
Íslenska
Italiano
עברית
Latina
Lietuvių
Magyar
മലയാളം
Nederlands
Nedersaksies
日本語
Occitan
Polski
Português
Română
Русский
Simple English
Српски / srpski
Srpskohrvatski / српскохрватски
Suomi
Svenska
Türkçe
Українська
Tiếng Việt
吴语
粵語
中文
35 more
Edit links
This page was last edited on 30 October 2018, at 20:52 (UTC).
Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
Privacy policy
About Wikipedia
Disclaimers
Contact Wikipedia
Developers
Cookie statement
Mobile view
Enable previews

key: html

type: local

value: div

attrs: id class

values: mw-page-base noprint

values: mw-head-base noprint

value: a

attrs: id class lang

values: firstHeading firstHeading en

values: siteSub noprint

values: mw-jump-link #mw-head

values: mw-jump-link #p-search

values: shortdescription nomobile noexcerpt noprint searchaux

value: img

attrs: alt src width height class srcset data-file-width data-file-height

attrs: href class title

attrs: href title

value: b

value: span

values:
/wiki/Gaia_(mythology)
mw-redirect
Gaia (mythology)

values:
/wiki/Global_temperature
mw-redirect
Global temperature

values:
/wiki/Atmospheric_oxygen
mw-redirect
Atmospheric oxygen

values:
/wiki/Habitability_of_Earth
mw-redirect
Habitability of Earth

values: The text near this tag needs further explanation. (December 2017)

values: checkbox button toctogglecheckbox toctogglecheckbox display:none

values:
/wiki/Biota_(ecology)
mw-redirect
Biota (ecology)

values:
/wiki/Methanogenic_bacteria
mw-redirect
Methanogenic bacteria

values:
/wiki/Earth%27s_atmosphere
mw-redirect
Earth's atmosphere

values:
/wiki/Piotr_Kropotkin
mw-redirect
Piotr Kropotkin

values:
/wiki/Vladimir_Ivanovich_Vernadsky
mw-redirect
Vladimir Ivanovich Vernadsky

values:
/wiki/Emergent_property
mw-redirect
Emergent property

values:
/wiki/Reducing_environment
mw-redirect
Reducing environment

values:
/wiki/Atmosphere_composition
mw-redirect
Atmosphere composition

values: Edit section: Regulation of global surface temperature

values:
/wiki/Climate_forcing
mw-redirect
Climate forcing

values:
/wiki/Greenhouse_gases
mw-redirect
Greenhouse gases

values: Edit section: Regulation of oceanic salinity

values: Edit section: Regulation of oxygen in the atmosphere

values: Carbon dioxide in the Earth's atmosphere

values: This claim needs references to reliable sources. (June 2012)

values:
noprint Inline-Template Template-Fact
white-space:nowrap;

values:
/wiki/Volcanic_activity
mw-redirect
Volcanic activity

values:
/wiki/Carbonate_rocks
mw-redirect
Carbonate rocks

values: This claim needs references to reliable sources. (July 2015)

values:
/wiki/Earth_Mother
mw-redirect
Earth Mother

values:
/wiki/Nobel_prize
mw-redirect
Nobel prize

values:
/wiki/Overview_Effect
mw-redirect
Overview Effect

values: Edit section: Formulation of the hypothesis

values:
/wiki/Life_on_Mars_(planet)
mw-redirect
Life on Mars (planet)

values:
/wiki/Endosymbiotic_theory
mw-redirect
Endosymbiotic theory

values:
/wiki/Christopher_Bird
mw-redirect
Christopher Bird

values: Edit section: Natural selection and evolution

values: it should be possible to find the original place where Hamilton said this (September 2012)

values: noprint Inline-Template noprint noexcerpt Template-Fact

values: Edit section: Criticism in the 21st century

values: display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle

values: margin:0.5em 0 0.5em 1em;border:solid #aaa 1px

values: -moz-column-width: 20em; -webkit-column-width: 20em; column-width: 20em;

values:
nofollow
external text
//www.worldcat.org/issn/1600-0870

values:
nofollow
external text
//doi.org/10.1023%2Fa%3A1014237331082

values:
nofollow
external text
//doi.org/10.1023%2Fa%3A1014218227825

values:
nofollow
external text
//doi.org/10.1038%2F277640a0

values:
nofollow
external text
http://www.snowballearth.org

values:
nofollow
external text
//doi.org/10.1038%2F326655a0

values: Category:CS1 maint: Multiple names: authors list

values:
nofollow
external text
//doi.org/10.1023%2FA%3A1023494111532

values:
nofollow
external text
//doi.org/10.1007%2FBF00002942

values:
nofollow
external text
//www.worldcat.org/issn/1573-515X

values:
nofollow
external free
http://www.webviva.com

values:
nofollow
external text
//doi.org/10.1126%2Fscience.1140325

values:
/wiki/PubMed_Identifier
mw-redirect
PubMed Identifier

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/17901330

values:
nofollow
external text
//doi.org/10.1073%2Fpnas.96.20.10955

values:
nofollow
external text
//www.worldcat.org/issn/0027-8424

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/10500106

values:
nofollow
external text
//doi.org/10.1029%2FGB002i004p00299

values:
nofollow
external text
//doi.org/10.1038%2F207568a0

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/5883628

values:
nofollow
external text
http://www.jameslovelock.org/page4.html

values:
nofollow
external text
//doi.org/10.1038%2F344100a0

values:
nofollow
external text
//doi.org/10.1029%2FRG027i002p00223

values:
nofollow
external text
//doi.org/10.1006%2Fjtbi.2000.2105

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/10968941

values:
/wiki/Charles_Cockell
mw-redirect
Charles Cockell

values:
nofollow
external text
//doi.org/10.1038%2Fnature10580

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/22129724

values: -moz-column-width: 30em; -webkit-column-width: 30em; column-width: 30em; list-style-type: decimal;

values:
nofollow
external text
//doi.org/10.1006%2Fjtbi.2002.3059

values:
nofollow
external text
//www.ncbi.nlm.nih.gov/pubmed/12297068

values: Temperature record of the past 1000 years

values: nowraplinks collapsible collapsed navbox-subgroup mw-collapsible mw-collapsed mw-made-collapsible

values:
/wiki/Anthropogenic_climate_change
mw-redirect
Anthropogenic climate change

values: List of scientists who disagree with the scientific consensus on global warming

values: Intergovernmental Panel on Climate Change

values: United Nations Framework Convention on Climate Change

values: Effects of climate change on plant biodiversity

values: Effects of global warming on human health

values: Effects of global warming on marine mammals

values: 2009 United Nations Climate Change Conference

values: United States withdrawal from the Paris Agreement

values: Individual and political action on climate change

values: Avoiding Dangerous Climate Change (2005 conference)

attrs: alt src title width height srcset data-file-width data-file-height

values: nowraplinks hlist collapsible autocollapse navbox-inner mw-collapsible mw-made-collapsible mw-collapsed

values: Category:All articles with dead external links

values: Category:Articles with dead external links from May 2017

values: Category:CS1 Spanish-language sources (es)

values: Category:Articles with short description

values: Category:Wikipedia articles needing clarification from December 2017

values: Category:All articles with unsourced statements

values: Category:Articles with unsourced statements from June 2012

values: Category:Articles with unsourced statements from July 2015

values: Category:All articles lacking reliable references

values: Category:Articles lacking reliable references from September 2012

values: Category:Webarchive template wayback links

values: Discussion about edits from this IP address [ctrl-alt-n]

values: A list of edits made from this IP address [ctrl-alt-y]

values: You are encouraged to create an account and log in; however, it is not mandatory

values: You're encouraged to log in; however, it's not mandatory. [ctrl-alt-o]

values:
/wiki/Gaia_hypothesis
View the content page [ctrl-alt-c]
c

values: Discussion about the content page [ctrl-alt-t]

values: p-namespaces navigation vectorTabs p-namespaces-label

values:
p-variants
navigation
vectorMenu emptyPortlet
p-variants-label

values: Past revisions of this page [ctrl-alt-h]

values: p-views navigation vectorTabs p-views-label

values:
p-cactions
navigation
vectorMenu emptyPortlet
p-cactions-label

values:
mw-wiki-logo
/wiki/Main_Page
Visit the main page

values:
/wiki/Main_Page
Visit the main page [ctrl-alt-z]
z

values: Featured content – the best of Wikipedia

values: Find background information on current events

values:
/wiki/Special:Random
Load a random article [ctrl-alt-x]
x

values: portal navigation p-navigation p-navigation-label

values: portal navigation p-wikibase-otherprojects p-wikibase-otherprojects-label

values:
interlanguage-link interwiki-af
display: none;

values: فرضية غايا – Arabic

values: গাইয়া অনুসিদ্ধান্ত – Bangla

values:
interlanguage-link interwiki-ca
display: none;

values:
interlanguage-link interwiki-cs
display: none;

values:
interlanguage-link interwiki-da
display: none;

values:
interlanguage-link interwiki-et
display: none;

values: Θεωρία της Γαίας – Greek

values:
interlanguage-link interwiki-el
display: none;

values:
interlanguage-link interwiki-eo
display: none;

values:
interlanguage-link interwiki-eu
display: none;

values: فرضیه گایا – Persian

values:
interlanguage-link interwiki-fa
display: none;

values: interlanguage-link interwiki-fr badge-Q17437796 badge-featuredarticle

values:
https://ga.wikipedia.org/wiki/GAIA
GAIA – Irish
ga
ga
interlanguage-link-target

values:
interlanguage-link interwiki-ga
display: none;

values:
interlanguage-link interwiki-gl
display: none;

values: 가이아 이론 – Korean

values:
interlanguage-link interwiki-ko
display: none;

values:
interlanguage-link interwiki-is
display: none;

values:
interlanguage-link interwiki-it
display: none;

values: השערת גאיה – Hebrew

values:
interlanguage-link interwiki-he
display: none;

values:
interlanguage-link interwiki-la
display: none;

values:
interlanguage-link interwiki-lt
display: none;

values:
interlanguage-link interwiki-hu
display: none;

values: ഗെയാ സിദ്ധാന്തം – Malayalam

values:
interlanguage-link interwiki-ml
display: none;

values:
interlanguage-link interwiki-nl
display: none;

values:
interlanguage-link interwiki-nds-nl
display: none;

values:
interlanguage-link interwiki-ja
display: none;

values:
interlanguage-link interwiki-oc
display: none;

values:
interlanguage-link interwiki-pl
display: none;

values:
interlanguage-link interwiki-ro
display: none;

values: Гипотеза Геи – Russian

values:
interlanguage-link interwiki-simple
display: none;

values: Геја хипотеза – Serbian

values:
interlanguage-link interwiki-sr
display: none;

values:
interlanguage-link interwiki-sh
display: none;

values:
interlanguage-link interwiki-fi
display: none;

values:
https://sv.wikipedia.org/wiki/Gaiateori
Gaiateori – Swedish
sv
sv
interlanguage-link-target

values:
interlanguage-link interwiki-sv
display: none;

values:
interlanguage-link interwiki-tr
display: none;

values: Гіпотеза Геї – Ukrainian

values:
interlanguage-link interwiki-uk
display: none;

values:
interlanguage-link interwiki-vi
display: none;

values:
interlanguage-link interwiki-wuu
display: none;

values:
interlanguage-link interwiki-zh-yue
display: none;

values: All languages (initial selection from common choices by you and others)

values: /static/images/wikimedia-button-1.5x.png 1.5x, /static/images/wikimedia-button-2x.png 2x

values: /static/images/poweredby_mediawiki_132x47.png 1.5x, /static/images/poweredby_mediawiki_176x62.png 2x

values:
suggestions
display: none; font-size: 13px;

values: mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-Gaia_hypothesis rootpage-Gaia_hypothesis skin-vector action-view