Chapter 13: Human Population

13.1 History of Human Population

13.2 Growth and Changing Needs

13.3 Challenges of Overpopulation

THOMAS MALTHUS

• 230 years ago (1798) Thomas Malthus published An Essay on the Principle of Population. 

• Stated the human population grows geometrically (2,4,8,16,32,64…) while the resources to support it grow arithmetically (1,2,3,4,5,6…). 

Thomas Malthus• Under these conditions

the population must inevitably outgrow the supply of food that is available to fulfill its needs. 

• Predicted that population growth would destroy the land, cause famine, disease and war in England and eventually all Europe.

Malthus’ Population Theory

• Malthus presented his theory in response to the “frontier ethic” that said we controlled our environment and owned everything in it.

• Improvements in

agriculture and the industrial revolution prevented Malthus’ theory from happening. But his ideas are still applicable today.  

HUMAN POPULATION GROWTHSince 1960, several factors have dramatically reduced infant and child mortality throughout the world: •use of DDT to eliminate mosquito-borne malaria• immunization against cholera, diphtheria, polio, smallpox and other diseases•discovery of antibiotics

Population Growth• The "Green

Revolution” increased food output:

• development of disease-resistant rice, wheat and corn

• use of fertilizers and more effective farming methods.

• These changes have produced a dramatic increase in human population growth rates.

Growth and Changing NeedsGrowth rate =

birth rate - death rate

(per 1000 people)

Doubling time =

is the time it takes at the

present growth rate for

the population to double

Demography =

the science of changing

vital statistics in a human

population.

In the next 2.5 years, the equivalent of the current U.S. population will be added to the planet. In this decade one billion people (the population of China) will be added.  U.S. National Academy of Sciences and British Royal Society state that population is growing at a rate that will lead to doubling by 2050.

http:/www.poodwaddle.com/worldclock.swf

POPULATION FACTS:The Earth's population reached 6

billion in September of1999.  Human population was only 2

billion in 1930. Every second, three people are

added to the world. Every day a quarter of a million

people are added to the world. Every year, about 87 million

people are added to the world

CARRYING CAPACITY OF THE EARTHThe earth cannot continue to support a massive population growth indefinitely.

Ecologists have often made use of the concept of carrying capacity for all ecosystems

Measures the pressures that rapidly increasing populations put on their environments.

Carrying capacity is simply the largest number of any given species that a habitat can support indefinitely.

Global Carrying CapacityHumans have:• Changed/harmed 49-50% of the

Earth’s surface

• Increased CO2 levels by 30%

• Contaminated 50% of accessible fresh water

• Replaced 20% of native plants and animals on islands

• Caused the extinction of hundreds of plant and animals species

Human Effects on EarthHumans cause habitat destruction and climate

change. In 20 minutes, we will destroy 1,200 acres of forest and emit 180,000 tons of carbon dioxide into the atmosphere worldwide. Less forest cover means fewer acres of habitat for species and more climate-changing carbon in the atmosphere. As climate, landscapes, and oceans change, species must move or adapt. Those that can’t simply die out.

Fisheries: 20% increase in fish catch before the alarming decline in Atlantic Cod and other major fisheries. Nine of the seventeen major fishing areas of the world are in serious decline, and all of them have either reached or exceeded their limits.     Cropland. Between 1980 and 1990, cropland area worldwide expanded by 2%. It expanded quickly, given that the areas already taken are the ones that are easiest to cultivateLand is being rapidly lost to various kinds of development.

Rangeland and Pasture. Similar calculations show a decline of 22% (and about 20% of this area is declining in productivity because of overgrazing).    Forests. Due to a combination of deforestation and population growth, forest area is decreasing by 30%.

THE EFFECTS OF HUMAN ACTIVITIES

Increase in population population leads to: •increased habitat loss •pollution problems (both local and global)•high energy use Most of the 3.6 billion people added to the world between now and 2030 will be born in the developing nations, where the overall growth rate is 2.1% per year. The top 3 fastest growing continents are Africa, South America and Asia:•Kenya, fastest growing, doubling time of 20 years •Latin America will double in 30 years •Asia will double in size in 36 yearsMany regions are already exceeding their carrying capacity; (cannot produce enough food to support their populations). Equatorial Africa is undergoing very rapid desertification and is unable to support the population presently living there.

UNCONTROLLED POPULATION GROWTH

Sub-Saharan Africa has the highest birth rate, the highest rate of population increase and the lowest use of contraceptives of any major region in the world.

Average annual population increase in sub-Saharan Africa is 3 percent, ranging from 2.5 percent to 3.8 percent. Food supply increases by only 1%. 12 countries of the region, women average more than seven children per family. Population of sub-Saharan Africa will double by 2016.

GROWTH RATE

Mexico City doubled its population between 1960 and 1970 doubled population again between 1970 and 1980

Honduras, Kenya, Iran and Guatemala double population size in less than 30 years

OTHER FACTORS THAT AFFECT POPULATION SIZELOCALIZED POPULATION

Emigration (leaving a geographic area)

Immigration (entering an new geographic area)

DEMOGRAPHY

Various factors affect the population and resource use in any geographic area.Breakdown includes GENDER: Male / Female

AGE: Under 15, 16-44, 45-60, Over 65

                                                                                  

         

DEMOGRAPHIC TRANSITION IN SWEDENBefore the transition, both birth and death rates are high, and the growth rate is zero or close to it.

Birth rate declines due to better education, better family planning, more career options for women, and reduced infant mortality which reduces the desire for large families. The growth rate declines, eventually to zero.

In the transitional phase, the birth rate remainshigh while the death rate declines due to better public health measures (e.g. immunization) and expanded food methods. Population growth is a result of the difference between death rate and birth rate (ignoring immigration and emigration for now), so the decreased death rate leads to a high growth rate.

Changing Needs• The more people – the

greater their needs• Changes in technology,

lifestyles, standards of living can affect the needs of a population

• Industrial societies use more energy than underdeveloped nations

• The least developed nations are expected to have the largest population growth

Challenges of OverpopulationNegative Effects:• Less resources

(minerals, food, fuel)• Less available land• More disease• More damage to the

environment (magnifying pollution)

13.3 Challenges of OverpopulationU.N. Conference on Population in Cairo in 1994 179 nations endorsed a new "Programme of Action" World governments provide universal access to reproductive health care by 2015 as a global human rights imperative. Focus on both population control and identifying the social problems that contribute to population growth and poverty. Q: Has the UN “Programme of Action” been successful? Justify your answer with 5 scientific facts.

Governmental Controls on Population Growth China limits the number of children a couple can have to ONE CHILD Incentives to ONE CHILD couples include

better housing preferential treatment in education

longer vacations monetary grants extra month’s pay additional maternity leave

Q: What social and economic problems are caused by a ONE CHILD policy? Would this policy work in the United States? Justify your answer with facts.