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 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 – 1 st 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