Chapter 7 The Human Population

Chapter 7

The Human Population

China’s Population•Human population size, affluence, and

resource consumption all have interrelated impacts on the environment.

•China:

•20% of world population (1.3 billion).

•Rapid economic development.

•Already largest producer of CO2, SO2.

•Soon to be world’s largest economy. US is current largest economy (307 million people)

Population control•Since 1970’s China has had a 1 child policy.

•Financial rewards for sticking to one, sanctions for 3 or more (10% salary reduction).

•Numerous tools to meet standards: Sterilization, abortion, designation of certain pregnancies as illegal (female infanticide and under reporting).

•Decades of highest birth rate now at 1.6 births per woman.

•Base so large it will take years to level off and decline.

China’s population grows cars too!

•1985-2002 China population grows 30%

•Vehicles grew by 500%

•Today 25 million private cars on road (from 3 million).

•Second largest consumer of petroleum.

•2006- 16 of 20 most polluted cities were in China.

Scientists Disagree on Earth’s Carrying Capacity

Figure

7.1

Every 5 days the global population increase by 1 million.

Changed about 400 years ago when agriculture, sanitation, vaccines, etc. began/improved.

Current human population 6.8 billion.

Scientists Disagree on Earth’s Carrying Capacity

•The following graphs show theoretical models of food supply and population size.

•One of the first notions that human population could exceed Earth’s Carrying Capacity (proposed by Thomas Malthus)

•Actual because of intellect

MANY FACTORS DRIVE GROWTH7.2

Factors that Drive Human Population Growth

•Demography- the study of human populations and population trends.

•Changes in Population Size

•Fertility

•Life Expectancy

•Age Structure

•Migration

Changes in Population Size

•Immigration- the movement of people into a country

•Emigration- the movement of people out of a country.

•Net migration rate- the difference between immigration and emigration in a give year per 1,000 people in the country.

Changes in Population Size

• Crude birth rate (CBR)= the number of births per 1,000 individuals per year.

• Crude death rate (CDR)= the number of deaths per 1,000 individuals per year.

• Global population growth rate =

(CBR- CDR) 10

• National population growth rate =

(CBR+ immigration) - (CDR + emigration) 10

• Doubling time (in years)-

70_____ growth rate

Fertility•Total fertility rate- an estimate of the

average number of children that each woman in a population will bear.

•Replacement level fertility- the total fertility rate required to offset the average number of deaths in a population and for the current population size to remain stable.

By 2050: 8.1-9.6 Billion

Expected to stabilize at 6.8-10.5 billion by 2100.

TFR•Total Fertility Rate: An estimate of

the average number of children that each woman in a population will bear in her childbearing years.

•Replacement Level Fertility: The TFR required to offset the average number of deaths in a population so that the current population size stays stable.

Fertility

•Developed countries- countries with relatively high levels of industrialization and income.

•Developing countries- countries with relatively low levels of industrialization and income of less that $3 per person per day.

Life Expectancy• Life expectancy- the average number of

years that an infant born in a particular year in a particular country can be expected to live, given the current average life span and death rate of that country.

Life Expectancy

• Infant mortality rate- the number of deaths of children under 1 year of age per 1,000 live births.

•Child mortality rate- the number of deaths of children under age 5 per 1,000 live births.

In 2009 the global infant mortality rate was 46. US infant mortality rate was 6.6.

Availability of prenatal care!

Even when things look good…

•Even when the overall numbers seem to indicate a high level of health care throughout the country, the reality may be strikingly different for portions of the population.

•Environmental Justice (more in chapter 20).

•Related to socioeconomic status and varying access to adequate nutrition and health care.

Age Structure

•Age structure diagrams (population pyramids)- visual representations of age structure within a country for males and females.

DEMOGRAPHIC TRANSITION7.3

The Demographic Transition

• The theory of the demographic transition is the theory that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a predictable shift in population growth.

Demographic Transition is not a complete picture though, it is a prediction: Nicaragua displays the birth and death rates of phase 4 even though its industrialization is that of phase 1 (developing).

The Stages of the Demographic Transition

• Phase 1: Slow population growth because there are high birth rates and high death rates which offset each other.

• Phase 2: Rapid population growth because birth rates remain high but death rates decline due to better sanitation, clean drinking water, increased access to food and goods, and access to health care.

• Phase 3: Stable population growth as the economy and educational system improves and people have fewer children.

• Phase 4: Declining population growth because the relatively high level of affluence and economic develop encourage women to delay having children.

Family Planning

•Family planning- the regulation of the number or spacing of offspring through the use of birth control.

As the education of women increase and women earn more money of their own, fertility goes down.

The 12 Most Populous Countries in the World

9 of the 12 most populous countries are developing.

Of Earth’s 6.8 Billion people, 5.6 billion live in developing countries. 1.3 billion live in developed nations: this 20% of the population uses over 50% of the resources. (2-10 times the environmental impact.

The relationship between economic development and population growth rate for developing nations.

Population growth in developed nations has mostly ceased, while population growth in developing nations is slowing, but expected to continue beyond 2050.

Ecological Footprints

•Affluence - having a lot of wealth such as money, goods, or property.

Average footprint for the 50 poorest countries is 1ha (2.5 acres).

U.S. = 9ha (22 acres)

China’s rapid development is likely to cause their Footprint to exceed US in 10 years.

The IPAT Equation

•To estimate the impact of human lifestyles on Earth we can use the IPAT equation:

•Impact= Population X Affluence X Technology

I=PAT (advanced)•Impact= Population X Affluence X

TechnologyStewardship

•Some of the most affluent countries have access to some of the best technologies that allow them to buy products that have less of an environmental impact. Technology can either degrade the environment or create solutions to minimize our impact.

The Impact of Affluence

•Gross domestic product (GDP)- the value of all products and services produced in a year in that country.

•GDP is made up of consumer spending, investments, government spending, and exports minus imports.

•A countries GDP often correlates with its pollution levels.

•As it increases further, it may reach a point where they are able to purchase equipment to burn fossil fuels more efficiently and cleanly.

Millennium Ecosystem Assessment

• Released in 2005, is an international synthesis by over 1000 of the world's leading biological scientists that analyses the state of the Earth’s ecosystems and provides summaries and guidelines for decision-makers.