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Environmental Lesson from Easter Island: Understanding Feedback Loops and Matter Quality

This chapter explores the collapse of Easter Island's thriving society due to the unsustainable use of resources. It highlights the concept of feedback loops, including positive and negative ones, as well as the importance of matter quality in resource extraction. The chapter also discusses the law of conservation of matter, types of pollutants, and nuclear changes.

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Environmental Lesson from Easter Island: Understanding Feedback Loops and Matter Quality

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  1. Chapter 2 Science, Systems, Matter, and Energy

  2. Core Case Study: Environmental Lesson from Easter Island • Thriving society • 15,000 people by 1400. • Used resources faster than could be renewed • By 1600 only a few trees remained. • Civilization collapsed • By 1722 only several hundred people left. Figure 2-1

  3. The people even cut down and used the trees to move the statues!!!

  4. Once the trees were gone, they couldn’t make canoes. • Without the forests to absorb and release water, streams dried up and soils eroded. • No more firewood for cooking!

  5. Collapse happened when rival clans fought each other for resources.

  6. Both the Earth and Easter Island are closed systems. Population and consumption are growing, but resources are finite!

  7. Feedback Loops: How Systems Respond to Change Video-albedo Video-feedback loops • Outputs of matter, energy, or information fed back into a system can cause the system to do more or less of what it was doing. • Positive feedback loop causes a system to change further in the same direction (e.g. erosion, money in a savings account, exponential growth, greenhouse effect) • Negative (corrective) feedback loop causes a system to change in the opposite direction (e.g. sweating, thermostat, predator-prey interactions). NASA - Top Story - RECENT WARMING OF ARCTIC MAY AFFECT WORLDWIDE CLIMATE - October 23, 2003

  8. Feedback Loops: • TIME DELAYS: Negative feedback (corrective feedback) can take so long that a system reaches a threshold or tipping point and changes its normal behavior. (balancing in your chair) • Example: a smoker can get lung cancer 20 years after having smoked his/her last cigarette. (population growth, degradation of forests, prolonged exposure to pollutants., EASTER ISLAND!!!!) • Synergy:2 or more processes interact so that the combined effect is greater that the sum of their separate parts. • E.g. smoking exacerbates the effect of asbestos exposure on lung cancer. (smoking 10x, asbestos 5x, together 50x)

  9. Matter Quality • Matter can be classified as having high or low quality depending on how useful it is to us as a resource. • High quality matter is concentrated and easily extracted. • Low quality matter is more widely dispersed and more difficult to extract. (Material efficiency-amount of material need to to produce goods and services) Figure 2-8

  10. Sample Test Question • In order to make one plastic soda bottle, approximately 100 liters of crude oil are • Used (including raw materials for plastic, fuel, etc.), 100 kilograms of steel, • 100 liters of water, and various amounts of other materials. Which of the • following describes this situation? • plastic bottles have a high resource productivity • .plastic bottles have a low material efficiency • plastic bottles represent an efficient use of resources • most of the matter used to manufacture plastic bottles ends up in the bottle • None of these answers.

  11. The Law of Conservation of Matter There is no “Away” • Matter cannot be created or destroyed, it can only change forms. • There is no “away” • We can burn it, bury it, apply it as a fertilizer…..it’s still there!

  12. Sample Test Question • All of the statements can be concluded from the law of • conservation of matter except… • We can’t throw anything away because there is no away. • We’ll eventually run out of matter if we keep consuming it at current rates. • There will always be pollution of some sort. • Everything must go somewhere. • We do not consume matter.

  13. Types of Pollutants • Factors that determine the severity of a pollutant’s effects: chemical nature, concentration (ppm/ppb/ppt), and persistence. • Pollutants are classified based on their persistence: • Degradable pollutants- broken down completely • Biodegradable pollutants-complex chemical pollutants that living organisms break down. (bacteria breaking down human sewage) • Slowly degradable pollutants-takes decades or longer (DDT) • Nondegradable pollutants-Natural processes can’t break down (lead-mercury-arsenic)

  14. Nuclear Changes: Radioactive Decay • The rate of decay is expressed as a half-life (the time needed for one-half of the nuclei to decay to form a different isotope).

  15. Half-Life Usually 10 half lives makes a radioactive material safe, material must be stored somewhere until it is safe. Iodine 131 has a ½ life of 8 days so in 80 days it’s safe. Plutonium 239 has a ½ life of 24,000 years so it’s safe in 240,000 years.

  16. Sample Test Question Uranium-235 has a half-life of 710 million years. If it is determined that a certain amount of stored U-235 will be considered safe only when its radioactivity had dropped to 0.10 percent of the original level, approximately how much time must the U-235 be stored securely to be safe? a.years d. years b. years e. years c. years

  17. After 200 million years, only 1/16th of the original amount of a particular radioactive waste will remain. The half-life of this radioactive waste is how many million years? • 12.5 • 25 • 50 • 75 • 100

  18. Nuclear Changes: Fission • Nuclear fission: nuclei of certain isotopes with large mass numbers are split apart into lighter nuclei when struck by neutrons. • Atomic bombs • Doable by humans • Less energy than fusion Video-fission Figure 2-9

  19. Nuclear Changes: Fusion • Nuclear fusion: two isotopes of light elements are forced together at extremely high temperatures until they fuse to form a heavier nucleus. • Harder to initiate • Produces more energy than fission • Energy of the sun! Figure 2-10

  20. ENERGY • First fire-then domestic animals-then wind/water energy-then steam (first wood then coal)-then oil-then nuclear-today 88% of our energy comes from fossil fuels. • High vs. Low quality • High-concentrated/ can perform useful work (electricity,coal,oil) • Low-dispersed/little ability to do work (heat dispersed in the atmosphere or ocean)

  21. Relative Energy Quality (usefulness) Source of Energy Energy Tasks Electricity Very high temperature heat (greater than 2,500°C) Nuclear fission (uranium) Nuclear fusion (deuterium) Concentrated sunlight High-velocity wind Very high-temperature heat (greater than 2,500°C) for industrial processes and producing electricity to run electrical devices (lights, motors) High-temperature heat (1,000–2,500°C) Hydrogen gas Natural gas Gasoline Coal Food Mechanical motion to move vehicles and other things) High-temperature heat (1,000–2,500°C) for industrial processes and producing electricity Normal sunlight Moderate-velocity wind High-velocity water flow Concentrated geothermal energy Moderate-temperature heat (100–1,000°C) Wood and crop wastes Moderate-temperature heat (100–1,000°C) for industrial processes, cooking, producing steam, electricity, and hot water Dispersed geothermal energy Low-temperature heat (100°C or lower) Low-temperature heat (100°C or less) for space heating Fig. 2-13, p. 44

  22. Sample Test Question • Which of the following energy sources has the lowest quality? • high-velocity water flow • fuelwood • food • dispersed geothermal energy • nuclear

  23. ENERGY LAWS: TWO RULES WE CANNOT BREAK • The first law of thermodynamics: we cannot create or destroy energy. • We can change energy from one form to another. • The second law of thermodynamics: energy quality always decreases. • When energy changes from one form to another, it is always degraded to a more dispersed form. • Energy efficiency is a measure of how much useful work is accomplished before it changes to its next form.

  24. Mechanicalenergy(moving,thinking,living) Chemical energy (photosynthesis) Chemical energy (food) Solar energy Waste Heat Waste Heat Waste Heat Waste Heat Fig. 2-14, p. 45

  25. SUSTAINABILITY AND MATTER AND ENERGY LAWS • Unsustainable High-Throughput Economies: Working in Straight Lines • Converts resources to goods in a manner that promotes waste and pollution. Figure 2-15

  26. Sustainable Low-Throughput Economies: Learning from Nature • Matter-Recycling-and-Reuse Economies: Working in Circles • Mimics nature by recycling and reusing, thus reducing pollutants and waste. • It is not sustainable for growing populations.

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