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Key Themes

  • Population Growth
  • Sustainability
  • Global Perspective
  • Urbanizing World
  • People and Nature
  • Science and Values

Human Population Growth

  • 35,000 years ago: ~3,000,000
  • 12,000 ya: ~15,000,000
  • 2,000 ya: ~100,000,000
  • Malthusian Population Growth
  • Population growth in the absence of resource limitation
  • Growth is proportional to the population
  • Equivalent to doubling at fixed intervals
  • Natural populations grow exponentially until they reach their carrying capacity
  • Carrying Capacity: the number of people, other living, or crops that a region can support

What Happens When a Population Reaches this Capacity

  • It reaches a logistic curve, staying under carrying capacity
  • If shot over then a rapid decline will occur
  • Carrying capacity is the maximum number of plants, animals, bacteria, etc that an environment can sustain
  • Carrying Capacity is not fixed
    • health of ecosystem
    • resource utilization
    • technology
    • quality of life
  • Humans carrying capacity estimates are variable (1-40 billion)

Sustainability

  • Sustainability of a resource
    • Harvesting no more than is replaced
  • Sustainability of an ecosystem
    • Human stressors
    • Natural disturbances
    • Ecosystem resilience
    • Biodiversity
  • What would sustainability look like?
    • Live without conflict with nature
    • Minimize pollution and risk
    • Restrained use of resources
    • Political system support
    • Minimize use of non renewable resources

A Global Perspective

  • Local actions have distant consequences
  • Remote regions are linked by atmosphere and water
  • DDT - 1962
    • Industrial Pesticide
    • Long half life in soils
    • Transported by runoff and rivers
    • Bio-accumulates
    • Linked to declines in aquatic life and birds
    • Human toxicity
  • The ozone hole
    • Protects from UV rays
    • Destroyed by refrigerants
    • Over Antarctica

An Urban World

  • Worldwide cities growing rapidly
  • Positives and negatives for environment
  • Can be more efficient
  • Less land per person
  • Reshapes land drastically

People and Nature

  • Humans are a product of nature, and have been shaped by and have always shaped nature
  • Prehistoric humans likely drove most large mammal species in North America to extinction
  • Invented agriculture, reshaped ecosystems
  • What is the natural world
    • Nature is always in a form of flux
    • What is the natural form?
    • Changed over time
  • What steps should we take to protect

Science and Values

  • Decision making relys on:
    • Personal values
    • Human equality
    • Economic Progress
    • Future Generations
    • Science
    • Assessing uncertain outcomes
  • Scientific knowledge is always being challenged
  • Theories can be disprove, but never proven
  • The classic scientific method is:
    • Observe phenomena
    • Formulate a question
    • Develop a hypothesis
    • Make predictions from hypothesis
    • Conduct experiment (tests) with potential to disprove hypothesis
    • Analyze results
  • The Precautionary Principle
    • States when there is a threat of serious, irreversible environmental damage we should not wait for proof before taking precautionary actions
    • It is better to err on the side of not destroying the earth
    • Why do we value the earth?