C
capital shallowing a decrease in the availability of capital per worker leading to reduced productivity per worker.

carrying capacity the level of population and consumption sustainable by the available natural resource base.

constant returns (to scale) a proportional increase (or decrease) in one or more inputs results in the same proportional increase (or decrease) in output.

D
demographic transition the tendency for first death rates and then birth rates to fall as a society develops economically; population growth rates first increase and eventually decrease.

dependency ratios the ratio of the number of people in a society who depend on others for their livelihood divided by the number who do not depend on others.

E
economies of scale expanded output increases returns per unit of input.

exponential growth a value that increases by the same percentage in each time period, such as a population increasing by the same percentage every year.

F
fertility rate the average number of live births per woman in a society.

fixed factors production factors whose quantity cannot be changed in the short run.

G
greenhouse effect the effect of certain gases in the earth’s atmosphere trapping solar radiation, resulting in an increase in global temperatures and other climatic changes.

gross annual population increase the total numerical increase in population for a given region over one year.

L
law of diminishing returns the principle that a continual increase in production inputs will eventually yield decreasing marginal output.

M
market failure the failure of certain markets to provide a socially efficient allocation of resources.

N
neo-Malthusianism the modern version of T. R. Malthus’s argument that human population growth can lead to catastrophic ecological consequences and an increase in the human death rate.

P
per capita output the total product of a society divided by population.

population age profile estimated numbers of people classified by age groups in a given place and time.

population cohort the group of people born within a specific time period in a country.

population growth rate the annual change in the population of a given area, expressed as a percentage of the total population.

population momentum the tendency for a population to continue to grow, even if the fertility rate falls to the replacement level, as long as a high proportion of the population is young.

R
replacement fertility level the fertility level that would result in a stable population.

S
solar flux the continual flow of solar energy to the earth.

T
technological innovation increases in knowledge used to develop new products or improve existing products.