Every second 4 or 5 children are born while only 2 people die. There is a net gain of 2.25 people per second.
Oct. 31, 2011 world population passed 7 billion and was growing at 1.13% per year.
We are adding ~80 million people per year!
Global population will double in 62 years if conditions remain unchanged.
Jan 1, 2017 population was ~7.4 billion
(In 2006 growth rate was 1.2% with a doubling in 58 years – so there is some improvement!)
POPULATION GROWTH IS A RECENT EVENT
Until the invention of agriculture 10,000 years ago, the human population was a few million people.
Populations were held in check by diseases, famine and war.
Early societies regulated their population through cultural taboos, abstinence and infanticide.
Human population began to increase rapidly after 1600 due to agricultural developments, better sources of power and better hygiene.
1 billion – 1804 5 billion – 1987
2 billion – 1927 6 billion – 1999
3 billion – 1960 7 billion – 2011
4 billion – 1974 8 billion – 2024??
Will we overshoot the carrying capacity?
VIEWS ON POPULATION GROWTH
Ecologists are concerned that overpopulation will cause environmental degradation that will threaten the ecological life-support systems on which we depend.
Economists often disagree with ecologists, arguing that economic and technological growth will enable us to solve these problems.
Social Justice Advocates argue that the root cause of many problems is inequitable distribution of the Earth’s plentiful resources.
PERSPECTIVES ON GROWTH
Thomas Malthus (1766-1834) wroteAn Essay on the Principle of Population in which he showed that human populations increase exponentially.
Population growth is checked by famine, disease, and cultural factors (e.g. late marriage).
Karl Marx (1818-1883) believed human population growth results from poverty and resource depletion
These two viewpoints are still debated today.
MALTHUS vs MARX
PERSPECTIVES ON GROWTH
Joel Cohen – mathematical biologist estimates our carrying capacity at 10-12 billion.
David Pimental a entomologist believes we will hit 12 billion in 2100 & birth control should be our #1 priority
Mohandas Gandhi stated “There is enough for everyone’s need, but not enough for anyone’s greed.”
TECHNOLOGY CAN INCREASE CARRYING CAPACITY
Technology can boost carrying capacity as we make progress in agriculture, engineering, commerce and medicine. These achievements make it possible to support many more people per unit area.
However, much of our growth has been based upon cheap, abundant fossil fuels. Will rising fuel prices constrain food production and distribution or some other critical factor?
ENVIRONMENTAL EFFECTS OF POPULATION
Effects of population on the environment are not due to numbers alone.
I = PAT
I = environmental Impact
P = Population size
A = Affluence
T = Technology
ie: A single American living an affluent lifestyle produces more pollution than an entire village of farmers in the third world.
CAN MORE PEOPLE BE BENEFICIAL?
More people mean larger markets, more workers, and increased efficiency due to mass production.
Economist Julian Simon believes that human intelligence and ingenuity will be able to solve the problems associated with population growth. “Humans are the ultimate resource”
Many leaders in developing countries believe the inequality of resource use and consumption is the biggest issue to be dealt with.
Populations expected to stabilize or decline (Japan, Italy, Germany)
Most couples have 1-0 children
Will experience societal issues as the population of young decline and the population of old rise
POPULATIONS OF WORLD’S LARGEST COUNTRIES
DECLINING POPULATIONS
RUSSIA – since collapse of Soviet Union is seeing pop. decline due to social issues: poor economy, crime, pollution. Abortions 2x live births. Male life expectancy has gone down
AFRICA - the AIDS epidemic has hit Africa the hardest. In Zimbabwe, Botswana, Zambia and Namibia, up to 39% of the population is HIV positive. In Botswana more than 2/3 of the 15 yr. olds now living will die of AIDS. Life expectancy has dropped to 31.6 years. (Should be 69.7 years)
WORLD POPULATION DENSITY
POPULATION IS NOT DISTRIBUTED EQUALLY
most people live near rivers or coastal plains
WORLD POPULATION DENSITY
FERTILITY AND BIRTH RATES
CRUDE BIRTH RATE (CBR)- Number of births in a year per thousand. (Not adjusted for population characteristics such as number of women of childbearing age.)
TOTAL FERTILITY RATE - number of children born to an average woman in a population during her life (1.9 TFR in the USA)
ZERO POPULATION GROWTH – (ZPG) Occurs when births plus immigration in a population equal deaths plus emigration.
Generally, this is a rate of 2.1 children per couple, because some people do not have children and some children do not survive.
DECLINE IN FERTILITY RATES WORLDWIDE
Fertility rates have declined everywhere except Africa. 100 out of 220 countries are at or near 2.1 replacement rate.
Greatest fertility reduction has been in Southeast Asia.
CHINA’S one child policy has decreased the fertility rate from 6 in 1970 to 1.5 in 2010.
A population growing rapidly due to natural increase has more young people than does a stationary population.
Even if total fertility rates were to fall, the population would continue growing as young people enter reproductive age (POPULATION MOMENTUM).
Some countries now have a stable population with the same number of people in each age group.
AGE STRUCTURE
AGE STRUCTURE
LIVING LONGER HAS IMPLICATIONS
Declining populations have more old people than young people.
Both rapidly and slowly growing countries can have a problem with dependency ratio.
DEPENDENCY RATIO - The number of non-working compared to working individuals in a population.
ie: In the U.S., fewer working age people will support many more retired people, and this is a problem for the Social Security & retirement systems.
ie: In Mexico, fewer working age people support many children – can lead to conditions of poverty
EMIGRATION (out) and IMMIGRATION (in)
Emigration and immigration play a large role in human population dynamics.
Developed regions can expect 2 million immigrants each year for the next 50 years.
Immigration is a controversial issue. “Guest workers” often perform dangerous or disagreeable work, while being paid low wages with few rights & poor conditions.
Locals argue that immigrants take away jobs and overload social services.
IDEAL FAMILY SIZE
SOCIAL, CULTURAL, RELIGIOUS AND ECONOMIC FACTORS AFFECT FAMILY SIZE.
Society’s need to replace its members may be codified into cultural or religious values.
Families with few children are pitied.
Controlling fertility may be taboo.
Boys are valued more than girls because they carry on the family name and often are expected to financially support parents in old age.
Couples may have more children than they really want in order to have a boy.
Having a large family in some cultures is a source of male pride.
BIRTH REDUCTION PRESSURES
Higher education and personal freedom for women often result in decisions to limit childbearing.
When women have more opportunities to earn a salary, they are less likely to have many children.
Education and socioeconomic status are usually inversely related to fertility in wealthier countries.
BIRTH REDUCTION PRESSURES
In DEVELOPING countries, higher income often means families can afford more children, thus fertility often increases, rather than decreasing as it does in developed countries.
In less-developed countries, adding another child to a family usually does not cost much
In DEVELOPED COUNTRIES, raising an additional child can carry significant costs.
BIRTH RATES IN THE UNITED STATES
Falling rate 1910-1929 due to transition from agricultural to industrial society
Baby boom after WWII – 1945-1965
Echo Boom as Baby-Boomers had children – smaller increase due to economics
FERTILITY OFTEN FOLLOWS ECONOMICS
COULD WE HAVE A BIRTH DEARTH?
Most European countries, as well as Russia, Asia, Japan, Singapore and Taiwan, are experiencing negative growth rates.
There are concerns in all these countries about a lack of young people to be soldiers, workers, and taxpayers.
One reason that birth rates may have dropped in developed countries is that toxins and endocrine disrupters that are pollutants interfere with sperm production. Sperm numbers and quality have fallen by half in the last 50 years.
Pattern of falling death rates and birth rates due to improved living conditions accompanying economic development.
PRE-MODERN SOCIETY - Poor conditions keep death rates high; birth rates are correspondingly high. (Stage I)
ECONOMIC DEVELOPMENT - brings better standard of living thus death rates fall. Birth rates stay constant or even rise. (Stage II)
DEMOGRAPHIC TRANSITION CONTINUED
In a MATURE INDUSTRIAL ECONOMY - birth rates begin to fall as people see that most of their children survive. (Stage III)
Populations continue to grow due to population momentum.
DEVELOPED COUNTRIES - Transition is complete and both death and birth rates are low and population is in equilibrium. (Stage IV)
IS DEMOGRAPHIC TRANSITION HAPPENING NOW?
Four conditions necessary for demographic transition:
improved standard of living
confidence that children will survive
improved status of women
birth control
Thailand, Indonesia, Colombia, Iran reduced fertility by 50+% in 20 years
Morocco, Peru, Jamaica, Mexico reduced fertility by 30-40% in 20 years
CAN DEMOGRAPHIC TRANSITION HAPPEN NOW?
Some demographers think that a demographic transition is taking place now in developing nations.
Growing prosperity and social reforms
More readily available technology
Developing countries can learn from past mistakes or developed countries
Modern communication increases expectations for change & development
DEMOGRAPHIC TRANSITION NOW?
Others take a more pessimistic view. Economist, Lester Brown warns that poorer countries may be caught in a demographic trap.
The population is growing so rapidly that there are not enough resources to complete modernization and enter stage IV.
Political instability & economic decline may be to blame
People who take this view urge birth control, education, and national policies that limit population growth.
SOCIAL JUSTICE
Still other demographers believe that in order for the demographic transition model to work, resources must be distributed more equitably.
They believe that the world has enough natural resources, but inequitable social and economic systems cause mal-distribution.
Many rich countries, when they were colonial powers, extracted the wealth from countries that were their colonies. Some of the world’s poorest countries had rich resources and adequate food supplies before they were impoverished by colonialism.
OTHER RIGHTS
Should consider the rights of other species?
Perhaps, rather than asking what is the maximum number of people that Earth can hold, we should instead ask what is the optimum number of people at which we can provide a fair and decent life for all humans while causing the minimum impact on other species and the biosphere.
WOMEN’S RIGHTS AND FERTILITY
Education and job opportunities for women reduce fertility rates.
When child mortality is high, parents tend to have high numbers of children to ensure that at least some survive. Improving child survival would reduce the number of births.
Land reform, political rights, job opportunities for women, and improved health for women translate into better survival for children and therefore lower fertility.
FERTILITY vs EDUCATION
FAMILY PLANNING and BIRTH CONTROL
FAMILY PLANNING - allows couples to determine the number and spacing of their children
- not necessarily fewer children, just decisions to have/not have more/less children
Percentage of married women with two children who do NOT want another child.
Garret Hardin’s Life Boat Ethic
“Each rich nation amounts to a lifeboat full of comparatively rich people. The poor of the world are in other much more crowded lifeboats. Continuously, the poor fall out of their lifeboats and swim for awhile, hoping to be admitted to a rich lifeboat, or in some other way to benefit from the goodies on board.... We cannot risk the safety of all the passengers by helping others in need. What happens if you share space in a lifeboat? The boat is swamped and everyone drowns. Complete justice, complete catastrophe.”
FUTURE OF HUMAN POPULATIONS
Most demographers believe the world population will stabilize sometime during the next century.
Projections of maximum population size
Low - 7 billion by 2050, then fall to 6 billion by 2150
Medium - 8.9 billion by 2050 then stabilize
High - continue to grow to 25 billion by 2150
High unmet need for family planning. Women in poorer nations often desire family planning but do not have access to it.
FACTORS THAT COMPLICATE FAMILY PLANNING
Religion and politics
U.S. was a leader in the International Conference on Population and Development in which 179 countries endorsed universally available family planning. Stipulation that abortion should never be promoted as family planning.
U.S. withdrew its financial support in 2000 as the political climate changed. (Bush) Claimed that ICPD could be interpreted as pro-abortion.
FACTORS THAT COMPLICATE FAMILY PLANNING
Some religions forbid birth control & encourage couples to have as many children as possible.
Societal changes are often needed to make family planning programs successful.
