Human Population

Population Demographics

I. Human Population Growth-A Brief History

• ZPG Video: Exponential GrowthWill any areas remain relatively unpopulated by 2030?

• Until a few hundred years ago, human population was stable-birth rate = death rate.

• About 400 years ago ag output and sanitation began to improve, so death rate dropped but birth rate remained high

• For most populations, exp growth halts when environmental limits are reached-are human populations constrained by limiting factors? Is there a carrying capacity for humans?

• Thomas Malthus 1798-pop growing exponentially while food supply is growing linearly."The perpetual tendency of the race of man to increase beyond the means of subsistence is one of the general laws of animated nature, which we can have no reason to expect to change." 

• Innovation and technological advances in food production have worked in the past.

II. Factors That Drive Human Population Growth

Demography: study of human populations and population trends

Factors• Changes in population size

CBR-CDR Current Global 20-8/10 = 1.2 % 10

• Fertility: – Total Fertility Rate: total number of children a women has in her

lifetime. – Replacement Level fertility: Total fertility rate required to offset

the total deaths in a population for the current population size to remain stable; number of children a couple must bear to replace themselves. Must include pre-reproductive mortality (2.1 in developed/2.5 in developing countries)

• Life Expectancy: Reported for overall pop, males only and females only– Infant and child mortality– Aging and disease

• Age Structure: proportion of males/females in age categories. Pre-reproductive, reproductive, post-reproductive– Population momentum: it takes time for actions that

attempt to reduced births to catch up with a growing population

• Migration: movement of people into and out of a country• http://www.npr.org/2014/02/04/269551459/an-afghan-

success-story-fewer-child-deaths

Fertility rates in the US

The top graph shows the total fertility rates for the United States between 1917 and 2010 and the bottom graph shows the country’s birth rate between 1917 and 2010. Question: The U.S. fertility rate has declined and remained at or below replacement levels since 1972. So why is the population of the United States still increasing?

This chart lists some major changes that took place in the United States between 1900 and 2000. Question: Which two of these changes do you think were the most important?

• Only 6 other countries have policies to encourage immigration

• Most migrants seek economic improvement or escape from religious persecution or political oppression.

• More and more are environmental refuges• Currently in US illegal immigration accounts for

44% of population growth-should we limit the rate at which immigrants are allowed to be able to deal with the enviro impact or keep this the land of opportunity for the poor and oppressed?

http://www.prb.org/Journalists/Webcasts/2010/usimmigration.aspx (6 mins)

Between 1820-1960 most immigrants came from Europe. Since 1960 Latin America (53%), Asia (25%), and Europe. In 2009, legal Hispanic immigrants

made up 15% of US pop; expected to be 30% by 2050

Effects of Declining Populations• Aging of Japan

• Immigration

• Global Aging and

Military Power

• AIDS

III. Demographic Transition

• Demographic transition refers to the transition from high birth and death rates to low birth and death rates as a country develops from a pre-industrial to an industrialized.

• 1919 American demographer Warren Thompson observed changes, or transitions, in birth and death rates in industrialized societies over the previous 200 years.

• Most developed countries are in stage 4 of the model; the majority of developing countries have reached stage 3. The major (relative) exceptions are some poor countries, mainly in sub-Saharan Africa and some Middle Eastern countries, which are poor or affected by government policy or civil strife, notably Pakistan and Afghanistan.

Can the World’s Developing Countries Make a Demographic Transition?

IV. Solutions: Reducing Population Growth

• Family Planning/National Policies

• Economic Rewards and Penalties

• Empowering Women

• Health Care

• Education

• Promote sustainable patterns of production and consumption

Cultural Carrying Capacity

• Garrett Hardin: How many people can the Earth support without overexploitation of resources and irreparable harm to the environment?

• Can we keep developing the new technologies and abilities to use new resources that enable increases in K?

• At what price will these developments come, relative to our quality of life?

Population Distribution and Urban Growth

A. Several trends important in understanding impact of Urban growth

• 2%-45% increase since 1850• Number of large cities mushrooming-Megalopolis• Most urban growth in developing countries• Poverty in urban areas increasingB. What are problems in urban areas?• Water shortages• Waste build up • Air pollution• Occupy 2% of land but consume 75% of resourcesC. Material World-What if we all lived like Americans

Smart Growth• Urban planning and transportation theory

that concentrates growth in compact walkable urban centers to avoid sprawl.

• Sustainable development goals include– expand the range of transportation options

employment and housing choices – equitably distribute the costs and benefits of

development – preserve and enhance natural and cultural resources– promote public health– https://www.southernenvironment.org/cases-and-projects/smart-

growth-in-the-southeast

Logarithmic graphs