The Human Population

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The Human Population

• Chapter 5

Applying the principles of population dynamics
and sustainability to the growth of the human
population
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Current Population Trends

• World population 7.18 billion in 2013
• Amplifies all environmental problems
• Largest increase expected in developing countries
  (approximately 97)
• Decreasing in some developed countries
• Rate actually decreased between 1963-2004, but
  the population has still doubled from 3.2 6.4
  billion

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Rate 80 million new people/year New York City
every month Germany every year United States
every 3.7 years
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Population projections For the next 20 years
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• Total Fertility Rate (TFR) - Number of children a
  woman has during her lifetime, averaged for
  population.
• same as biotic potential (r)
• Replacement Level Fertility - Number of children
  needed to replace everyone in the population.
• Varies between regions
• 2.1 with low infant mortality
• 2.5 with high infant mortality
• Zero Population Growth - Birth rate equals death
  rate.

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Sex Ratio - Age Distribution

• Sex Ratio- Relative number of males and females
  in a population
• Age Distribution - Number of individuals of each
  age in a population
• Together they tell how a population will grow

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Population Age Structure
Developing Countries
Developed Countries
Growth is determined by teenagers the
population wave of the future. 30 of popn lt15
years 1.9 billion more into reproductive years.
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Population Trend Comparisons

• Developed Countries
• Low infant mortality rate
• Life expectancy 77 years
• Total fertility rate 2.0
• 21 population lt15
• 12 population gt65
• Per capita GDP 36,110

• Developing Countries
• High infant mortality rate
• Life expectancy 52 years
• Total fertility rate 5.7
• 44 population lt15
• 3 population gt65
• Per capita GDP 800

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Human Population Issue

• Several factors determine the impact of a society
  on natural resources.
• Population size
• Population density
• Degree of technological development
• Demography - Study of populations and their
  characteristics.
• Larger ecological footprint in U.S. than in
  developing countries. Why?

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Environmental Impact
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The fertility rates have significantly fallen
since 1950.
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U.S. Birth Rates 1910-2004
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Demographic Transition
As countries become industrialized, death rates,
then birth rates decline.
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• Major social factor determining family size is
  the role of women in society.
• Early marriages foster high fertility rates.
• Lack of education opportunities for women reduces
  their options.
• When level of education increases, fertility
  rates fall.
• The most important factor is the ability of women
  to control the size of their family.

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Case Study Slowing Population Growth in China

• Economic incentives (food, large pensions, better
  housing, salary bonuses, free schooling)
• Free medical care
• Free sterilization
• Locally administered
• Very intrusive and coercive
• Problem with parents selecting for males
• Fertility rate decreased from 5.7 in 1972 to 1.7
  in 2004.

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Global Megacities
Number of large cities growing. Worlds urban
population will increase from 3.1 billion to 5
billion from 2004-2030.
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URBANIZATION- urban sprawl

• Using up land to build bigger cities
• Results in
• -Loss of crop land and animal habitats
• - Loss of wetlands
• -DEFORESTATION

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Problems include -Lower food production, -Less
oxygen production, -Less filters for
pollution, -More erosion- can lead to
DESERTIFICATION
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Increased impervious surfaces means more
flooding and more heat reflected back to the
atmosphere- GLOBAL WARMING
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HABITAT FRAGMENTATION- makes it difficult for
species to migrate, reproduce
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POLLUTION

• SMOG
• ACID RAIN

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RESOURCES

• RENEWABLE

• NONRENEWABLE

• Solar
• Wind
• Plants
• Water

• Fossil Fuels
• Oil
• Coal
• Gas
• Metal

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And a larger ecological footprint
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POLLUTION in the FOOD CHAIN

• Some pollutants can be magnified as you move up
  the food chain and cause problems.
• Example- DDT used as an insecticide

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BIODIVERSITY

• Total of all the genetically variations (DNA) in
  all the organisms in the biosphere
• Why is this important?
• Medicine
• Antibiotics

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Types of biodiversity

• ECOSYSTEM DIVERSITY- different habitats
• SPECIES DIVERSITY- estimated over 30 million
• GENETIC DIVERSITY- all the DNA in a species or
  communtiy

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ECOLOGICAL HOT SPOTS

• Place where many species and habitats are in
  danger of extinction

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LIMITING FACTORS

• Something that controls the growth of a
  population
• Examples-

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DENSITY DEPENDENT LIMITING FACTORS

• Affect larger populations much more than smaller
  populations

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DENSITY INDEPENDENT LIMITING FACTORS

• Affect all populations regardless of size