Principles of Environmental Science Inquiry and Appications

I = PAT Formula

I- Our environmental impacts

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P-  are the product of our population size

A- times affluence

T- and the technology used to produce the goods and services we consume.

Ecological Footprint
Estimates the relative amount of productive land required to support each of us.


encompasses vital statistics about people, such as births, deaths, and where they live, as well as total population size. 


(derived from the Greek words demos [people] and graphein [to write or to measure])


Ecological Footprint Analysis
Estimating the amount of territory needed to support all your consumption of food, paper, computers, energy, water, and other resources.
Crude Birth Rate

-The most accessible demographic statistic of fertility

-The number of births in a year per thousand persons

-Statistically “crude” in the sense that it is not adjusted for population characteristics, such as the number of women of reproductive age.

Total Fertility Rate
The number of children born to an average woman in a population during her entire reproductive life.
Zero Population Growth (ZPG)
Occurs when births plus immigration in a population just equal deaths plus emigration.
Replacement Rate
The number of children per couple needed to maintain a stable population.  Becuase of early deaths, infertility, and nonreproducing individuals, this is usually about 2.1 children per couple.

Crude Death Rates

(AKA Crude Mortality Rates)


Are expressed in terms of the number of deaths per thousand persons in any given year.
Life Expectancy
The average age that a newborn infant can expect to attain in any given society.

Dependency Ratio



the number of nonworking compared with working individuals in a population.
Pronatalist Pressures
The factors that increase people’s desire to have babies.
Demographic Transition


The pattern that goes from high birth and death rates to lower birth and death rates.;


Family Planning
Allows couples to determine the number and spacing of their children.
Birth Control
Usually means any method used to reduce births, including celibacy, delayed marriage, contraception, methods that prevent embryo implantation, and induced abortions.