TwentyFive Years of Thinking Green

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• Twenty-Five Years of Thinking Green
• -In 1971 Barry Commoner advanced four laws of
  ecology that have had a major impact on our
  thinking in classic book The Closing Circle.
• Everything is connected to everything else.
• Everything must go somewhere.
• Nature knows best.
• There is no such thing as a free lunch.
• What do these laws convey in the context of
  environmental science?

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• Twenty-Five Years of Thinking Green
• -hydrocarbon emissions from automobiles decreased
  by gt50.
• -number of large cities violating clean-air
  standards has dropped from 40 to 9.
• -lead emissions reduced by 98 because of the use
  of unleaded gasoline.
• -industrial toxic waste spills cut by 43.
• -many species have been removed from the
  endangered species list.
• -mandatory recycling laws have been implemented
  in 6600 U.S. cities.
• -100 million acres have been set aside as
  wilderness areas.
• -since 1979 the country has invoked energy
  savings to five times all the new sources
  combined.
• -the number of environmental groups on college
  campuses increased from 50 in 1989 to over 2000
  in 1995.

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• Earth Systems and Cycles
• A system is a set of (components) which are
  interconnected (related and operate together) to
  one another.
• The universe is the only truly isolated system
  where there is no exchange of energy or matter
  through its boundary.
• The earth may be considered a closed system where
  there is only an exchange of energy through its
  boundary.
• Open systems such as the hydrosphere or
  lithosphere exchange energy and matter over their
  respective boundaries.

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• Earth Systems and Cycles
• In open systems linkages between components cause
  mutual adjustments (feedbacks) between
  components. As one variable affects a second
  variable, the second variable causes a change in
  the first variable.
• -Negative Feedback (self-regulation)
• -Positive Feedback (snowball effect,
  self-enhancing)

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Earths Energy Cycle
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5000
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Earths Energy Balance How is the earths
carbon cycle tied to its energy balance?
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Hydrologic Cycle Reservoir and Fluxes (shown by
red arrows.
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Population doubling time 70/growth rate ().
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Compare the population doubling time of the
African nations versus North America or Europe.
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Relative importance of atmosperic gases and
particulate matter on global warming versus
cooling.
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