Human Population

SOME ALARMING STATISTICS

• Late 1600’s – ½ billion people• 1830 – 1 billion• 1930 – 2 billion• Since 1975 – world’s population has added 1

billion ever 12 years• Greatest growth occurring in developing

countries• By 2050 – 10.5 billion

Causes of “explosion”

• Technology• Improved sanitation• Better medical care• Increased agricultural output• These and others led to a decrease in death

rates, primarily infant death rates

Environmental Impacts

• Cornucopian view – resource depletion is not a problem if new resources can be found to replace

• Not all resources are replaceable• Even if it could, could we maintain the quality

of life we desire?

Environmental Impacts

• IPAT Model represents how human impact (I) results from interaction among three factors:

• Three factors: population, affluence, technology

I = P x A x T• Impact can be boiled down to pollution and/or

resource depletion

DEMOGRAPHY

Demography

• The science of human population• Principles of population ecology apply to

humans• Humans have a carrying capacity set by

environmental limitations• Estimates: 1-2 billion living prosperously to 33

billion living in poverty

Demography

• Uneven distribution means certain areas bear more burden

• Areas of low population density are often vulnerable to impact (sensitive environment that cannot support many people)

• Age structure diagrams show relative sizes of each age group in a population; used to predict future population dynamics

Demography

• Population growth depends on rates of birth, death, immigration, and emigration= (birth + immigration) – (death + emigration)• Immigration and emigration play a large role

today• Since 1970 growth rates in many countries

have been declining

Demography

• Total Fertility Rate (TFR): average number of children born per female during her lifetime

• Replacement fertility is the TFR that keeps the size of a population stable; for humans it is 2.1

• A lower infant mortality rate has reduced people’s tendency to conceive many children to ensure some survive

• Natural rate of population change is change due to birth and death rates alone

Demography

• Many nations experience a change called demographic transition

• This is a model of economic and cultural change that explains the trends in declining birth and death rates as nations industrialize

• Four stages: pre-industrial, transitional, industrial, post-industrial

Demography

• Despite technological advances, earth does not have enough resources for existing and future generations to maintain standard of living equal to developed countries

• Is the demographic transition universal?

POPULATION AND SOCIETY

Civil Rights for Women

• In societies in which women are freer to make reproductive decisions, fertility rates have declined

• Children are better cared for, healthier, and better educated

Population Policies

• Thailand – relied on education-based approach to family planning

• India – 1st country to implement population control measures. Strident policies in the 1970’s. Now focus on education, family planning

• Brazil, Mexico, Iran, Cuba et al, have instituted programs with reduction targets, incentives, education, contraception and reproductive health care

Population Policies

• UN in 1994 – Cairo conference on population & development. 179 nations endorsed all gov’ts to offer repro health care w/in 20 years

• US has often declined to fund family-planning efforts by the UN

Other Factors & Influences

• Poverty is strongly correlated with pop growth• Consumption from affluence creates huge

impact on environment• 1999 – the richest 20% of people used 86% of

world’s resources• HIV/AIDS leads to premature deaths, reducing

life expectancy in African nations• AIDS is undermining ability of developing

countries to make transition modern tech