Announcements16 February 2010

Current estimated World Population

U.S. 310,825,424 (10 million more than one year ago)

World 6,900,142,775(100 million more than one year ago)

12:30(CST), Feb 15, 2011

www.census.gov/main/www/popclock.html

Human population growth

Long lag phase, then exponential growth

Will human populations stabilize at K, or overshoot (or have we already?)

Human population growth

Currently…

6.9 billion humans on Earth tripled since 1900; 9.3 billion

expected by 2050 Overall, 1.14% annual growth

rate 75 million more people each year

What are the consequences of so many people?

Two views on what more people means:

• Resource depletion

• Pollution• Overcrowding• Famine• Poverty• Overshooting

carrying capacity?

• Larger markets• More workers• Efficiency of scale • More innovation

Contrasting Views on Human Populations

Rev. Thomas Malthus (1798) argued human populations tend to increase exponentially while food production is plentiful.

- Humans inevitably outstrip food supply and eventually collapse (lead to poverty).

- Humans are too lazy and immoral to voluntarily reduce birth rates.

“An Essay on the principle of Population”

Contrasting Views on Human Populations

Karl Marx (1848) argued that population growth is a symptom rather than a cause of poverty and other social problems.

- Real causes of these problems are exploitation and oppression.

- The way to slow population growth and alleviate many social problems is through social justice.

Thomas Malthus

Karl Marx

Current views….

Neo-Malthusians - Believe we are approaching, or have already surpassed, the earth’s carrying capacity.

- We should make over-population issues our first priority.

Neo-Marxists - Believe eliminating oppression and poverty through social justice is the only solution to the population problem.

- Wealth and resource distribution must be addressed.

What factors influence human population growth?

Same as for other species: Birth rate Death rate Sex ratio Age distribution Immigration/emigration Density

Study of these for humans called demography

Birth rates and Death rates

Sex Ratio

Humans have roughly 1:1 sex ratio

Total Fertility Rate – number of children a woman has during lifetime

Replacement Fertility = 2.1 children/female/lifetime (leads to zero population growth in long term)

Age Distribution

U.S. Age Distribution over time

“Baby boom” (1946 - 1964) changes major societal concerns

Housing, schools,

supplies for children

University education,

large young workforce

Retirement, elderly

heath care

Child care, luxury items,

productive working years

Immigration/Emigration

Of 0.9 % increase in U.S. pop, 0.3% is due to immigration

Millions of people want to emigrate from war-torn, poverty-stricken countries to more stable, developed countries

Population Density

Number of people per unit land area As density increases, more environmental

impacts

Distribution of people within countries also important.

47% of world’s population in cities, expected to increase to 60% by 2025

Problems with dense populations in cities: Water transported long distances Wastes difficult to get rid of Decreased air quality Large burden on local environment Social unrest due to economic disparity

Population Density

Social & political factors influence human population growth

What determines how many children a woman has?

What policies do countries have on population growth? Immigration?

Major social factors affecting birth rates

1. Cultural role/status of women In male-dominated societies, traditional role

of women is to marry & have children Women not educated, encouraged to marry

young Lack of education makes women dependent

on husband, children

Women in developed countries are often educated, have option to delay marriage or not marry

Major social factors affecting birth rates

1. Cultural role/status of women, cont.

Early marriage = more child-bearing years = more children

% of births by 15-19 year olds: Africa 17% Latin America 16% All developed countries 3%

Major social factors affecting birth rates

2. Desires of women to have children & access to birth control

Women in less-developed countries have more children than they want

Often little access to birth control, education on how to use

Religious views on birth control

However, women in less-developed countries want more children than women in developed countries.

Economic value of children

In less-developed countries:

Guard against high infant mortality

Security in old age Labor force

= desire for more children

In developed countries: High probability of

survival Large economic

expenditure not put into retirement plan

Increase labor by parents

= desire for fewer children

Political policies on population growth

Encouraged in some countries (U.S., European) by subsidies: Paid maternity leave Guaranteed jobs Childcare Tax deductions

Need younger workers to support aging populations

Political policies on population growth

Discouraged in other countries

China:One child limit started in 1979

Contraception and abortion readily available and widely used.

Result: Current total fertility rate of 1.72

Result: Current total fertility rate of 2.78 children (goal of 2.1 by 2010)

India:1. Little government

intervention until recently2. Some states emphasizing

improving quality of life- Decrease infant mortality - Encourage education for

women3. Others enforcing sterility

Political policies on population growth

Effect of different policies

Pop size growth rate

China 1.3 billion 0.6%India 1.1 billion 1.4%

US 300 million 0.9%

(2006 estimates from CIA world fact book)

Political policies on immigration

Countries with low birth rates (European, Japan, China) may face shortage of workers without immigration

Emigrants want to move to developed countries to improve standard of living

Practice Exam Question

Which of the following bests describes the views of Rev. Thomas Malthus and Karl Marx?

A) Malthus and Marx both believed that excessive population growth leads to poverty, famine and political strife

B) Malthus and Marx both believed that poverty, famine and political strife leads to excessive population growth

C) Malthus believed that excessive population growth leads to poverty, famine and political strife, while Marx believed that poverty, famine and political strife leads to excessive population growth

D) Malthus believed that poverty, famine and political strife leads to excessive population growth, while Marx believed that excessive population growth leads to poverty, famine and political strife

Considerations in Ecological Economics

Common property resources – public ownership

Common ownership essentially means no owner.

Strong tendency to overexploit and misuse the resource.

Common ownership makes it virtually cost-free for anybody to cause pollution.

Hardin argued that many societal issues, including human population growth and the fair use of public space had “no technical solution”.

Garrett Hardin (1968), The Tragedy of the Commons

article in the journal Science

Pasturelands provided free by government to anyone wishing to graze cattle.

Common Pasture, open to all

Rancher 1 Rancher 2

Tragedy of the Commons

Each rancher seeks to maximize personal wealth, does individual cost-benefit analysis

Common Pasture, open to all

Rancher 1 Rancher 2

Tragedy of the Commons

Rancher 1: For each animal I add to my heard, I gain wealth (Benefit of +1)

Rancher 1 Rancher 2

Cost of adding one animal is a slight decrease in the resource

But, the cost is shared by all ranchers (Cost in this example: -1/2)

Rancher 1 Rancher 2

Optimal Solution for Rancher 1: Keep adding more animals

Cost = -1/2Benefit = +1Benefit > Cost

Rancher 1 Rancher 2

Optimal Solution for Rancher 2: Keep adding more animals

Cost = -1/2Benefit = +1Benefit > Cost

But, cost / benefit analysis is the same for Rancher 2

Rancher 1 Rancher 2

The pasture can only support so many animals

Eventually, resource is overexploited at a serious cost to everyone

•Tragedy of the Commons has already been observed at the local and regional level

- Cattle grazing on western public rangelands.- Overfishing in the oceans (international

waters)Ecosphere (the planet Earth) is a large commons

U.S. and other industrialized nations consume more than fair share of resources and freely uses the commons to dispose of waste

Tragedy of the Commons

Surprising Nobel in Economics

by: Michael Mandel, October 12, 2009

I have an admission to make—I had never heard of Elinor Ostrom before this morning’s Nobel prizes in Economics were announced. Ostrom, the 2009 winner was honored “for her analysis of economic governance, especially the commons.”

Ostrom focused on a subtle question—if you have a shared “common-pool resource” like a forest or the ocean, what is the right way to manage it? Typical answers have focused on either collective management (i.e. government control) or effective privatization (i.e. fishing permits). But Ostrom has argued that all sorts of other institutions can grow up over time that give good results.

Surprising Nobel in Economics

Ostrom’s principles for good management of collective resources:

(i) rules should clearly define who has what entitlement(ii) adequate conflict resolution mechanisms should be in place(iii) an individual’s duty to maintain the resource should stand in

reasonable proportion to the benefits.iv) monitoring and sanctioning should be carried out either by the

users themselves or by someone who is accountable to the users.vi) governance is more successful when decision processes are

democratic in the sense that a majority of users are allowed to participate in the modification of the rules

(vii) the right of users to self-organize is clearly recognized by outside authorities

Sustainable Development

Viability of natural resources over time, and the maintenance of human living standards and economic growth.

Sustainable Development – Meets present needs without compromising ability of future generations to meet their own needs.

By the end of this lecture you should be able to:

1. Describe the past, present, and projected future world population of humans (explain figure on slides 3 & 4).

2. List the 6 factors that affect human population growth rate.3. Explain why women have more children in male-dominated

societies and fewer children in developed countries.4. List the two factors have the greatest control on birth rates.5. Recall the current size of the World Population and the US

Population. 6. Explain how political policies in China and India changed

their population growth rates.