I have found the Population Card produced by the United Nations Fund for Population Activities to be a good device for highlighting the rapid increase of world population. At the beginning of a talk I can share the estimated world population for that time and then, since the card updates itself every minute, I can share the amount of increase during the course of my remarks.
As the literature that comes with the card indicates, the global population exceeded five billion in 1987 and is expected to increase to 6.2 billion by the end of the century. Nearly 90 percent of this increase will take place in developing countries.... Combined with rapid urbanization, the rapid population growth generates unprecedented demands for more services in terms of food, clothing, housing, education, health and employment as well as environmental protection.
Driven by a tiny battery, the Population Card calculates and displays the estimated population of the world, or of any one of 165 countries programmed into it, at any point in time between the years 1989 and 2020. It fits easily into pocket or purse and is handy as a clock, calendar and calculator.
One example for its use can be found in relation to Dr. Hardin's article about Bangladesh on page 197 of this journal. One turns the card on by pushing C/P for country population. After reading the figure for the US, the down arrow is pushed until the country BGD appears. Push enter and the estimated current figure is posted for Bangladesh. One minute later that figure changes by 6. If we move over to the calculator mode and multiply 6, times 60, times 24, we realize that there are 8640 estimated births in 24 hours. It would take about 17 days to add 150,000 persons.
The Population Card can be obtained for $21 postpaid from UN Population Fund, File PCMFSO-Population Card, 220 East 42nd Street, New York, NY 10017.