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Roberts 2011

Roberts 2011. Population Dynamics - Trends Population Projections – UN All scenarios include shifts in geographic distribution of population Medium variant Africa – 23.6% of population in 2050 (15.0% today) Asia – 55.3% in 2050 vs. 60.3% today Europe – 7.7% in 2050 vs. 10.6% today

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Roberts 2011

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  1. Roberts 2011

  2. Population Dynamics - Trends • Population Projections – UN • All scenarios include shifts in geographic distribution of population • Medium variant • Africa – 23.6% of population in 2050 (15.0% today) • Asia – 55.3% in 2050 vs. 60.3% today • Europe – 7.7% in 2050 vs. 10.6% today • N. America – 4.8% in 2050 vs. 5.0% today • Latin America – 8.1% in 2050 vs. 8.6% today • Shifts in age structure

  3. Roberts 2011

  4. Roberts 2011

  5. Population – Environmental Effects • Factors • Population growth alone isn’t only factor contributing to environmental impact • Population • Per-capita consumption rate • Impacts of consumption (waste disposal, etc.) • CFC emissions and their impacts are related to technology, not population • World could support an additional billion people (estimate) if all humans were vegetarians

  6. Population – Environmental Effects • Ehrlich – “Earth can support a larger population of cooperative, far-sighted, vegetarian pacifist saints than of competitive, myopic, meat-eating, war-making typical human beings. All else being equal, Earth can hold more people if they have relatively equal access to the requisites of a decent life than if the few are able to monopolize resources and the many must largely do without. The problems of population, social and economic inequity, and environmental deterioration are thus completely intertwined.”

  7. Population – Environmental Effects • Not all humans impact the environment equally • Industrialized nations currently house 22% of the world’s population but consume • 60% of food • 70% of energy • 75% of metals • 85% of wood • Generate 75% of CO2 emissions

  8. Population – Environmental Effects • I = PAT (Ehrlich and Holdren) • I = Environmental Impact of nation • P = Population • A = Affluence (reflects consumption) • T = Technology (reflected in pollution) • Ex – Changes in CFC emissions related to technology, not population • Developments in technology historically not directed toward environmental preservation • “Ecological Footprint” • Area per capita to provide resources utilized • Compare to area available per capita in nation

  9. Population – Environmental Effects • I = PAT (Ehrlich and Holdren) • I for one American equals • 20 Costa Ricans • 70 Bangladeshis • UN Children’s Fund – Child born today in US will have 250x impact of child born in sub-Saharan Africa over their lifetimes • Different consumption patterns and life expectancies • Annual US Population increase = 2.9 million • 58 million Costa Ricans (pop 4.6 million) • 203 million Bangladeshis (pop 149 million)

  10. Population – Environmental Effects • I = PAT (Ehrlich and Holdren) • Energy Usage - 1 American = • 2 Japanese • 6 Mexicans • 13 Chinese • 32 Indians • 372 Ethiopians • Annual population increase in US – 2.9 million people • Equivalent in energy usage to adding • 92.8 million Indians (actual – 18 million) • 1.079 billion Ethiopians!

  11. Overpopulation – Resource Availability • Resource Costs • In 1980, Julian Simon issued a “public offer to stake US$10,000 ... on my belief that the cost of non-government-controlled raw materials (including grain and oil) will not rise in the long run.” • Paul Ehrlich and two colleagues accepted challenge • “The Bet” • Ehrlich and colleagues selected five metals (chromium, copper, nickel, tin, tungsten) they felt would undergo large price increases. • They purchased (on paper) $200 worth of each on Sep 29 1980. • They designated Sep 29 1990 as the date to evaluate the bet. • If the inflation-adjusted prices of these metals rose, Simon would pay Ehrlich $10,000. If the prices fell, Ehrlich would pay Simon the loss in value. • During this 10-year period, the world’s population grew by over 800 million people. • The price of each of the five metals dropped, in some cases substantially (e.g. tin fell from $8.72/pound to $3.88/pound). • Ehrlich lost the bet, to the tune of $576.07.

  12. Overpopulation – Problem or Not? • Overpopulation is a problem because: • Depletion of non-renewable resources  Warfare!!! (Diamond) • Susceptibility to disasters (natural and otherwise) • Waste disposal • Soil depletion • Unequal distribution of resources (increasing gap b/w rich & poor) • Increase in pollution (Woolridge) • Expansion of development (habitant modification) • Younger generation supporting older generation • Overpopulation is not a problem because: • Increasing technological efficiency (Eberstadt) • Overall production okay; need better distribution system • Resources becoming less scarce (prices going down, not up) • Rate of population increase slowing • Utilize empty space more effectively (Ruse) • History of ~successful adaption • Most growth in developing nations with low resource use • Potential for new technologies (e.g. GMO foods with higher nutritional value)

  13. Overpopulation – Problem or Not? • Organize into groups • As a group: • List three most compelling reasons why overpopulation is a problem • List three most compelling reasons why overpopulation is not a problem • Overall, do you think that overpopulation is a major environmental problem?

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