Human Population Unit 5 Environmental Science 1

Exponential Growth Characterized by doubling Starts slowly, but rapidly increases Total growth in one doubling is more than the total of all preceding growth Exponential growth occurs when the rate of growth is directly proportional to the number present – ΔN/Δt ≈ N

Exponential Growth Doubling time equation is: – Doubling time = 70/% of annual growth (r) – So if the annual growth rate is 2% then 70/2=35 years to double the population

Human Population A group of organisms living in a group is called a population Population growth leads to an increase in food, energy, pollution and other resource consumption Energy is a major concern as the population grown

Human Population Carrying capacity is the maximum population Earth can reasonably sustain an average standard of living In the beginning of history the world population has changed very little because the death rate and birth rate were relatively equal However, recently the birth rate began to out number the death rater? Why?

Human Population

Human Populations Changes in population size are recorded and monitored by demographers Demographers use the numerical equation to express changes in the population: – Population growth = Birth rate – death rate This does not take into consideration immigration and emigration

Human Populations

Developed vs. Developing Countries Developed countries are technologically advanced and have a high standard of living Developing countries have a low standard of living Developed countries tend to have a lower growth rate because of better education and health care Developing countries have higher birth and death rates

Developed vs. Developing Countries

World Population Trends In 2000 the population surpassed 6 billion The population has reached 7 billion as of 2011 The current growth rate is about 1.3% with a doubling time of about 54 years

World Population Trends 98% of the growth is occurring in developing countries The growth rate has slowed since 1965 – why?

World Population Trends It is predicted that the world’s population will stabilize at 10.2 billion by 2100 and the replacement level of 2 children per couple will be reached by 2035 However, some say the population will not stabilize until 11.2 billion

World Population Trends How did they come up with this data? – Declining importance of children needed for labor – Increased cost of raising children – Improved social status of women – Rising education level and improved employment