GAIA DECONSTRUCTED

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GAIA DECONSTRUCTED

• TREN 1P90
• Sustainability, Environment and Tourism

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GAIA IN A NUTSHELL

• Earth has remained a comfortable place for living
  organisms for the whole 3.5 billion years since
  life began, despite a 25 increase in the heat
  output of the sun during that time.

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GAIA IN A NUTSHELL

• The atmosphere is an unstable mixture of reactive
  gases, yet its composition remains breathable for
  long periods of time for whoever happen to be the
  current inhabitants.

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GAIA IN A NUTSHELL

• If the composition of the earth's atmosphere was
  governed solely by the laws of chemical
  equilibrium, virtually none of the free oxygen,
  methane, or other highly reactive gases that it
  contains would be present in their existing
  proportions

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GAIA IN A NUTSHELL

• Example
• The thin atmosphere of Mars

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GAIA IN A NUTSHELL

• But our atmosphere is an unstable mixture of
  highly reactive gases that persists, against all
  the expectations arising purely from the laws of
  physical chemistry.

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GAIA IN A NUTSHELL
What drives this system?
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GAIA IN A NUTSHELL

• The GAIA HYPOTHESIS states that living organisms
  have always actively kept the planet fit for
  life
• The earth's metastable yet highly reactive
  atmosphere is evidence of a living system

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GAIA IN A NUTSHELL

• But if the second law of thermodynamics tells
  us that entropy in the universe is increasing,
  how does life avoid the universal tendency for
  decay?

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GAIA IN A NUTSHELL

• A living organism is able to decrease its
  internal entropy at the expense of free energy
  taken from the environment, and subsequently
  rejecting it in a degraded form.

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GAIA IN A NUTSHELL

• By the process of photosynthesis or the
  consumption of food, living organisms use energy
  from the environment to maintain their internal
  order and organization.

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GAIA IN A NUTSHELL

• If the excretion of entropy from the organism is
  as large or larger than the internal generation
  of entropy, the organism maintains its internal
  organization and continues to live.

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GAIA IN A NUTSHELL

• Metastable environmental conditions on the
  surface of the planet are determined by the
  collective action of the biota.
• This HOMEOSTASIS is the net result of the
  interactions of living organisms with one another
  and with their physical environment.

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GAIA IN A NUTSHELL

• This interaction is not predetermined, mystical,
  or divinely ordained, nor does it require
  cooperation or altruism between groups of
  organisms.
• It is an emergent phenomenon resulting from the
  interaction of living and nonliving subsystems in
  the ecosphere.

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GAIA IN A NUTSHELL

• The major benefit of the Gaia hypothesis was as a
  metaphor to capture the public imagination about
  the important role of living organisms in
  maintaining environmental conditions on the
  earth, particularly through their effects on the
  global atmosphere.

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GAIA IN A NUTSHELL

• Implications regarding
• Biodiversity conservation
• Habitat protection
• Global climate change
• Integrity of natural ecosystems
• Collective interdependence of all of the biota on
  the planet

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Emergence of Metastability in Complex Systems

• The Daisyworld Model

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The Daisyworld Model

• A cybernetic model which demonstrates how
  theinteraction of simplevariables can resultin
  outcomes which are unpredictable to the unaided
  human mind

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The Daisyworld Model

• explains temperature regulationby the biota on a
  simple model planet

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The Daisyworld model starting assumptions

• Assume constant CO2 levels and no cloud cover
• Assume heat inputs are from the sun and heat
  losses occur through radiation into space

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The Daisyworld model starting assumptions

• One environmental variable examined TEMPERATURE
• Daisyworld has a planetary surface that reflects
  40 of incoming lightwhen barren

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The Daisyworld model starting assumptions

• One environmental variable examined TEMPERATURE
• One single type of biota DAISIES, either black
  or white

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The Daisyworld model starting assumptions

• An otherwise barren planetary surface that
  reflects 40 of incoming light
• A sun with solar output increasing over time
  (normal stellar evolution, just like our own sun)

(The energy output of our own sun has
increased 25 in the 3.5 billion years since life
began)
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The Daisyworld model starting assumptions

• Mean temperature of Daisyworld is thus determined
  by the average reflectance (albedo) of the planet
  surface (including the daisies)

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The Daisyworld model starting assumptions

• Primarily black daisies low albedo,heat energy
  absorbed by surface
• Primarily white daisies high albedo, heat energy
  reflected by surface

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The Daisyworld model starting assumptions

• Daisies do best at about 20 C
• If it is too cold (lt5 C), daisies wont grow
• If it is too hot(gt40 C), daisies will die

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Barren planet
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Conventional wisdom model
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Geophysiology model
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Daisyworld simulation

• http//gingerbooth.com/courseware/daisy.html