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3.1.1-.2 Human Pop Growth

3.1.1-.2 Human Pop Growth. Human population growth. This question is difficult to answer. Estimates are usually based on food, but human agriculture limits assumptions on available amounts. Human population growth rate has been growing more than exponentially. .

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3.1.1-.2 Human Pop Growth

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  1. 3.1.1-.2 Human Pop Growth

  2. Human population growth

  3. This question is difficult to answer. • Estimates are usually based on food, but human agriculture limits assumptions on available amounts. • Human population growth rate has been growing more than exponentially. What is the carrying capacity of Earth for humans?

  4. 1999 1975 domestication of plants, animals 9000 B.C. (about 11,000 years ago) agriculturally based urban societies beginning of industrial, scientific revolutions HUMAN POPULATION GROWTH

  5. Expansion of habitat • Increased capacity in existing habitats • Substituting and importing resources • Population has sidestepped limiting factors: • Technology (agriculture) • Medicine Increase in growth rate:

  6. The availability of food and water Invasion of parasites, pathogens, or disease Over-crowding Severe or sudden climatic changes Pollution of air, soil and water Population size has limits beyond which even humans can easily control:

  7. If we do not take steps to control human population growth, it is likely that one or more of these growth-limitingfactors will eventually kick in to forcibly reduce our numbers.

  8. Crude birth rate = the number of births per thousand individuals in a population per year. Crude death rate = the number of deaths per thousand individuals in a population per year. Fertility = the potential of reproduction exhibited in a population. Measuring Population Growth

  9. Developed Nations Developing Nations

  10. Natural increase rate = the form in which human population growth rates are usually expressed Crude birth rate – crude death rate 10 Measuring population growth

  11. 4.5 Developing Countries 3.0 Population (billions) Developed Countries 1.5 Projections 0 1950 1970 1990 2010 2030 Year Human Population growth = 1.4% per year Developing nations = 1.7% Developed nations = 1.0% Growth rate

  12. Doubling time (T) = 70 . annual percentage rate (g) Doubling Time Doubling time = the number of years it would take a population to double its size at its current growth rate. Doubling time (T) = 70 . = 50 years 1.4

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