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

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

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

7. If we do not take steps to control human population growth, it is likely that one or more of these growth- limiting factors 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.

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

11. Human Population growth = 1.4% per year Developing nations = 1.7% Developed nations = 1.0% 19501970199020102030 Year 4.5 3.0 1.5 0 Population (billions) Developing Countries Developed Countries Projections

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