Chapter 8 Human Population Issues World population growth is a contributing factor in nearly all environmental problems Population Trends Projected to have 7.8 billion people by the year 2025. Most of the increase will be in Africa, Asia and Latin America already have 82% of population. has lowest GNP has lowest “standard of living” Greatest impact of AIDS on Sub-Saharan Africa

Chapter 8 Issues: How does population growth contributes to all “world problems”?. - famine - political unrest - environmental degradation from poor agricultural practices - water pollution - air pollution - loss of biodiversity - destruction of natural resources

Chapter 8 Demands of some populations are more damaging than other populations: Developed countries demands are much higher than developing countries.   Developed countries demands are spread around the world. Developing countries export resources to developed countries.

Chapter 8 Causes of Growth Birth rates and death rates: è growth rate should be controllable  if death rate exceeds birth rate than population declines reducing birthrate is “better” than increasing death rate Demography Study of human populations May use sex ratios and age distribution w/in population to predict future growth  

Chapter 8 Factors to consider: 1. Number of women having children.  2. Number of children born to each woman. è if total fertility rate (number of children born in a woman’s lifetime) is 2.1, human population will stabilize   è “zero population growth”

Chapter 8 Stabilization will not happen immediately: death rate will decrease as people live longer.   initially, many young people will start having families. è may take from 20 to 100 years to stabilize.

Chapter 8 Social Reasons Desired family size is determined by religion, tradition, social and economic factors.   Male-dominated cultures places high value on women having and raising children (usually when quite young) and little value on educating women. Female education is key

Chapter 8 Birth control only helps if people want to limit the size of their family.   Why want a large family? if infant mortality is high. Breast feeding can lower infant mortality have children to support you in your old age. more family members to earn income. Children work in high population growth areas

Chapter 8 Political Factors Some countries have population goals or laws and even offer incentives (tax breaks, free birth control).   China has used more political techniques than any other country, and their population is still not stable.

Chapter 8 Demographic Transition Concept: High standard of living occurs in areas where population growth is small.   Likewise, low standard of living occurs in areas where population growth is high. è has led to the suggestion that countries naturally go through stages (based on European and North American experience) demographic transition

Chapter 8 Can all countries go through this demographic transition?   Those that already have, did so when energy, natural resources and land were abundant because world population was low. Technological development is unlikely to keep up with the large populations now occurring.

Chapter 8 U.S. population: About 275 million today. low birthrates and growth rates (0.8% from births, 0.3% from immigration). “baby boomer” bulge in the population pyramid.   è by 2030, 20% of population will be 65 years old or older. è population size about 383 million by 2050 - ethnic differences

Chapter 8 Impacts on the environment: Will have to shift some biomass to food for the human population.   It is easy to mismanage agricultural systems and create much damage (e.g. the Dust Bowl). Long term impacts of providing food by reducing biodiversity are unknown. Can feed more people on plants than animals. Remember trophic levels?