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World Population Growth - Page | 1 World Population Growth Purpose: Graph and mathematically analyze the rates of human population growth through history. Project human populations into the future based on generalization from various data source for modern times. Introduction There is a close connection between the human population of the Earth and many of the problems we currently face as a global society. Issues such as resource depletion, energy consumption, global food supplies, drinking water reserves, soil erosion, water and air pollution, global climate patterns, and many others are directly related to the growing number of people living on our planet. Fig. 1-1 This long range population projection, from United Nations sources, focuses on divergent trends between industrialized and less-developed nations. As seen in Figure 1.1, since about 1950 differing population trends between the developing and industrialized regions of the world have further complicated the situation. In this exercise you will examine human growth trends closely and draw conclusions about population numbers – and problems – in the coming generations. Materials: graphing paper or Excel software Internet access World Population Growth - Page | 2 Exercise I: Historical Overview and Application Procedure: 1. Plot the data below on a piece of graph paper. These are good estimates of world population at various times since the beginning of human civilization. Year Population 8000 BC 4000 BC 500 BC AD 500 AD 1000 AD 1500 AD 1700 AD 1900 AD 1950 AD 1980 AD 2000 Note: If using Excel, substitute the directions in the box for steps 2-4 below. 2. Plot years along the x-axis and label this axis Time. Start at 8000 BC, letting each inch equal 1000 years. Attention: Set your scales carefully, the data points are not uniformly spaced. 3. Label and plot the population, in billions, along the y-axis. If you are using graph paper ruled in inches, let each inch equal 1 billion people. Each tenth of an inch then equals 100 million people. Lab Hint: Data for the earliest years will be difficult to plot exactly to this scale. If available, metric ruled graph paper is easier to use. 4. Draw a smooth line that best connects all the data points. 4 million 7 million 100 million 200 million 250 million 400 million 600 million 1.6 billion 2.5 billion 4.5 billion 6.1 billion Excel Directions: Open the file “population data” from NetClassroom. The data have been entered already. Note that the BC dates have been entered as negative values for ease of plotting. a. First, convert the population data from millions of people to billions of people.(This may be done for you.) b. Select year data and the population data (in billions) including the header row. c. Go to the Insert tab and select Scatter from the Charts menu. d. Select Scatter with Smooth Lines and Markers. This will construct a graph with time on the x-axis and population on the y-axis. All of the points will be connected. World Population Growth - Page | 3 Analysis: Answer the following questions using the graph that you constructed. The questions are listed on the next page for you to answer in Word and e-mail to me. 1. Examine the shape of the plotted line on your graph. a. What type of mathematical relationship exists between human population and time? b. Identify and describe the regions of the graph that represent the Lag Phase, Growth Phase, and the Stationary Phase. c. Define what is meant by the terms “J” curve and “S” curve. Review pp. 163-164 in your text for help. 2. Analyze the patterns of growth after 2000. a. Predict the world’s population in the year 2050 and plot it. Excel Directions: Open the file “population data” from NetClassroom. a. Enter desired year in cell A14. In this case type “2050” without the quotes into cell A14. b. Insert the following formula, without the parentheses, into box B14: =GROWTH(B9:B13,A9:A13,A14,TRUE) c. The number in box B14 shows the predicted exponential growth of the world population (in millions) for the year entered in box A14 based on the actual data from the past century. If you change the year in box A14, the world population value will change accordingly. b. Explain why this value may be realistic. Also give a reason why it may not be. c. Describe how three environmental problems we now face would change if your predicted value came true. 3. Estimate as best you can the doubling time (in years) for the population after each period: a. 8000 BC _________ 500 BC ________ 1700 BC _________ 1900 ________ 1950 _________ 1980 ________ 2000 _________ b. Is the doubling time at each of the above points in history getting longer or shorter? c. Read “Doubling Time and Exponential Growth” on page 11 of your text. Using the “Rule of 70,” calculate the rate of population growth for each of the above intervals. Show your calculations. d. Graph the doubling times over time. e. Use your graph of doubling times to predict the rate of growth and the population in the year 2050. References Population Growth Over Human History (1996) http://www.globalchange.umich.edu/globalchange2/current/lectures/human_pop/human_pop.html