3.1.1-.2 Human Pop Growth. Human population growth. 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?
domestication of plants, animals 9000 B.C. (about 11,000 years ago)
agriculturally based urban societies
beginning of industrial, scientific revolutions
HUMAN POPULATION GROWTH
Invasion of parasites, pathogens, or disease
Severe or sudden climatic changes
Pollution of air, soil and waterPopulation size has limits beyond which even humans can easily control:
If we do not take steps to control human population growth, it is likely that one or more of these growth-limitingfactors will eventually kick in to forcibly reduce our numbers.
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.Measuring Population Growth
Developed Nations individuals in a population per year.
Natural increase rate = the form in which human population growth rates are usually expressed
Crude birth rate – crude death rate
10Measuring population growth
4.5 growth rates are usually expressed
Human Population growth = 1.4% per year
Developing nations = 1.7%
Developed nations = 1.0%Growth rate
Doubling time (T) = growth rates are usually expressed 70 .
annual percentage rate (g)Doubling Time
Doubling time = the number of years it would take a population to double its size at its current growth rate.
Doubling time (T) = 70 . = 50 years