HUMAN POPULATION DYNAMICS

7 Billion http://www.youtube.com/watch?v=sc4HxPxNrZ0&feature=share&list=PL7WxmjMiAYikNGKPUWeZxBNOhKsd8LxSo

Core Case Study: Is the World Overpopulated? The world’s population is projected to increase from 6.6 billion to 8.9 billion between 2006 and 2050. (We are already at 7 billion now.) The debate over interactions among population growth, economic growth, politics, and moral beliefs is one of the most important and controversial issues in environmental science.

Core Case Study: Is the World Overpopulated? Much of the world’s population growth occurs in developing countries like China and India. India will soon overtake China in population Figure 9-1

Core Case Study: Is the World Overpopulated? Some argue that the planet has too many people, and eventually we will out grow our resources. Some feel that the world can support billions of more people due to technological advances. There is a constant debate over the need to reduce population growth. Must consider moral, religious, and personal freedom.

HUMAN POPULATION GROWTH: A BRIEF HISTORY The human population has grown rapidly because of: the expansion of agriculture, industrial production, and lower death rates from improvements in hygiene and medicine. In 2006, the population of developed countries grew exponentially at 0.1% per year. Developing countries grew (15 times faster at 1.5% per year.

Where Are We Headed? We do not know how long we can continue increasing the earth’s carrying capacity for humans. There are likely to be between 7.2-10.6 billion people on earth by 2050. 97% of growth in developing countries living in acute poverty. Some developing countries are beginning to aquire greater wealth and produce a high demand on natural resources. What is the optimum sustainable population of the earth based on the cultural carrying capacity?

Where Are We Headed? U.N. world population projection based on women having an average of 2.5 (high), 2.0 (medium), or 1.5 (low) children. Figure 9-2

Population (billions) High High 10.6 Medium Low Medium 8.9 Population (billions) Low 7.2 Figure 9.2 Global connections: UN world population projections, assuming that by 2050 women have an average of 2.5 children (high), 2.0 children (medium), or 1.5 children (low). The most likely projection is the medium one—8.9 billion by 2050. (Data from United Nations, World Population Prospects: The 2001 Revision, 2002) Year Fig. 9-2, p. 173

Factors Affecting Human Population Growth Crude Birth rate – number of births per 1,000 individuals in a period of time. Highest in developing countries Lower in developed countries Crude Death rate – number of deaths born per 1,000 individuals in a period of time.

FACTORS AFFECTING HUMAN POPULATION SIZE Growth Rate- uses birth rate, death rate, immigration, & emigration to calculate population growth/change. Instead of using raw numbers, crude birth rates and crude death rates are used (based on total number of births or deaths per 1,000 people in a population).

Growth rate (Birth rate-death rate) + (immigration – emigration) / 10 If a population of 10,000 experiences 100 births, 40 deaths, 10 immigrants and 30 emigrants in a year, what is the net annual percentage growth rate?

Growth Rate Problems Calculate the growth rate for the following population: A population with a crude birth rate of 18 per 1,000, a crude death rate of 10 per 1,000, and immigration rate of 5 per 1,000, and an emigration rate of 7 per 1,000 would have a growth rate of _________. (18/1,000 + 5/1,000) – (10/1,000 + 7/1,000) = 6/1,000 Growth Rate x 100% 6/1,000 x 100% = 0.6%

Annual Rate of Natural Population Change (%)= Birth rate – Death rate 1,000 people x 100

Doubling Time Doubling time is the amount of time needed for a population to double in size. Doubling Time = 70 / Growth Rate Ex. A population has a growth rate of 2%. How long will it take for the population to double? Doubling Time = 70/2 Doubling Time = 35 years

Age Structure: Young Populations Can Grow Fast How fast a population grows or declines depends on its age structure. Prereproductive age: not mature enough to reproduce. Reproductive age: those capable of reproduction. Postreproductive age: those too old to reproduce.

Question of the Day The Republic of Congo has a growth rate of 2.83 with a population of 4,492, 689 people. Calculate the amount of time it will take for the population to double. Show your work. Doubling Time= 70/ Growth Rate Doubling Time= 70/ 2.83 Doubling Time= 24. 73 years