ATMOS 397G Biogeochemical Cycles and Global Change Lecture 2: GAIA Hypothesis

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ATMOS 397GBiogeochemical Cycles and Global
ChangeLecture 2 GAIA Hypothesis

• Don Wuebbles
• Department of Atmospheric Sciences
• University of Illinois, Urbana, IL
• January 23, 2003

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Course Website

• Class Website
•  http//www.atmos.uiuc.edu/courses/atmos397g-sp03
• You are welcome to give your suggestions to
  improve the site!

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GAIA

• Ancient Greece Mother Earth
• Gentle, feminine and nurturing but ruthless with
  any that failed to live in harmony with the Earth
• James Lovelock The Sustaining Earth
• Earth has a self-regulating system for
  maintaining life on Earth
• Controversial
• Simple example Daisyworld

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Control system / regulation
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Basic Premise for Daisyworld

• Cloudless planet with negligible greenhouse
  effect
• A planet that can support life
• Surface temperature of the planet is affected by
  its depth of color dark planet ?warmer T
• Daisies need a minimum temperature to grow (5C),
  with optimum growth at 22.5 C (birthrate at
  maximum) and death at 40 C.
• Variable solar input (0.6 to 2.0 times in model
  we will use)
• Variable solar insulation the degree to which
  each color daisys area maintains its own local
  temperature rather than equilibriumto the global
  temperature.
• No other variable factors, example no CO2.

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Daisyworld

• Simplest version two types of daisies, light and
  dark relative to the soil different albedos
  (reflection of sunlight)
• Can have multiple colors of daisies, however, or
  even add in other lifeforms (not in model we will
  use)
• Relationship between temperature and daisies
  leads to self-sustaining population
• SHOW MODEL EXAMPLE
• ?Daisies respond to varying solar input by
  changing fraction of each daisy color to maintain
  the global temperature.

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More Complex Daisyworld