GAIA DECONSTRUCTED

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GAIA DECONSTRUCTED

• ENVI 1P90
• Introduction to Sustainability

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ENTROPY

• a calculable physical quantity
• entropy of a system is zero at absolute zero
  (i.e. -273oC)
• entropy increases with the addition of heat
  energy, but not in direct proportion

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ENTROPY...

• connected in quantitative terms with the
  orderliness of things
• the greater the order, the lower the entropy

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ENTROPY...

• ...may be defined as (choose your favourite)
• a measure of the total energy of a system that is
  not available to do work
• a measure of the degree of randomness or disorder
  in a system

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ENTROPY...

• Units of measure
• CALORIES per GRAM per DEGREE
• - total quantity of heat energy added, divided
  by the temperature

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• Solid in a beaker
• heated by burner flame at constant rate

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• Solid - liquid
• temperature rises, but NOT in a linear fashion

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• Liquid - gas
• temperature rises, but NOT in a linear fashion

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GAIA IN A NUTSHELL
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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.

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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, and 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.

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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 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 stable 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

• Stable 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.
• Weak Gaia
• ESS (Earth Systems Science)