Unit 5

• Tragedy of the Commons


  The idea that if you have a shared public resource, everybody uses it in their own interest, and it's degraded at the expense to everybody
• Tragedy of the Commons


  • Overgrazing on a field that isn't owned by anybody
  • Overfishing in the oceans, which aren't owned by anybody
  • Water and air pollution
• Ways to solve Tragedy of the Commons

  • Privatize the resource to give individuals an incentive to manage it sustainably
  • Impose fees or taxes for overusing a resource
  • Implement command and control approaches, such as the Clean Air Act or the Clean Water Act
  • Establish organizations, like the Bureau of Land Management, to manage land and prevent tragedy of the commons
• Clear-Cutting and Forest Management

  • Soil erosion
  • Less shade for streams, resulting in increased stream temperatures and less dissolved oxygen
  • Higher turbidity, which can cause flooding and landslides
  • Replacement with non-native tree plantations, which can lower biodiversity
• Ecosystem Services provided by forests

  • Filtering air and removing carbon
  • Providing habitat for organisms
  • Performing transpiration, which pumps water into the atmosphere
• The Green Revolution


  The industrialization of agriculture, which includes: Increased use of mechanization, Genetic modification of organisms, New irrigation and fertilization methods, Increased use of pesticides
• Benefits of the Green Revolution

  • Increased food yields
  • Decreased world hunger
• Environmental Consequences of the Green Revolution

  • Increased use of fossil fuels
  • Compaction and loosening of soil, making it less productive and more prone to erosion
  • Decreased biodiversity of crops
  • Increased use of synthetic fertilizers, leading to eutrophication and climate change
• Mechanization


  • Increased use of tractors, which compact and loosen soil, making it less productive and more prone to erosion
  • Increased use of fossil fuels
• Genetic Modification of Organisms

  • Produced crops with higher yields
  • Resulted in less biodiversity of crops
  • Could mean less pesticides necessary, but also results in decreased biodiversity
• Types of Irrigation


  • Drip irrigation (most efficient, but also most expensive)
  • Furrow irrigation (least efficient, results in most water runoff)
  • Flood irrigation (used for rice paddies, can result in methane emissions)
  • Spray irrigation (more expensive than furrow irrigation, but more efficient)
• Water Logging


  Water takes up space in the soil, causing roots to die or be stunted due to lack of air
• Soil Salinization


  Water evaporates, leaving salt behind, making soil unsuitable for plants
• Most water is used in agriculture
• Consequences of using Groundwater

  • Confined aquifers being recharged slower than unconfined aquifers
  • Pollution staying in the aquifer for longer
  • Saltwater intrusion in coastal areas
  • Cone of depression, drying up neighboring wells
• Pest Control


  • Chemicals are used to control pests, but can lead to: Pesticide treadmill, where more chemicals are needed due to resistance, Killing beneficial organisms
  • Alternative: genetically modified organisms with built-in pesticides, but can decrease genetic diversity
• Meat Production


  • Most meat comes from Confined Animal Feeding Operations (CAFOs), which: Maximize land use and profit, Use antibiotics to prevent disease, Use large amounts of water, Contaminate water with manure, Produce greenhouse gas emissions
  • Alternative: free-range grazing, which reduces density of organisms and requires less antibiotics
• Overgrazing


  Can result in: Soil compaction, Erosion, Desertification (turning an area that was not a desert into a desert)
• Rotational Grazing


  A way to more sustainably graze animals on land by rotating them from one area to another
• Energy Efficiency of Meat Production

  Eating meat is far less energy efficient than other food sources because: We're eating higher up in the food chain, With each trophic level up, 90% of the energy is lost. This is true for energy, water, and nutrient perspectives as well.
• Overfishing and Fisheries Collapse

  • Overfishing can result in: Fisheries collapse (where the population cannot come back), Decreased tourism, Decline in ocean ecosystems, Huge economic consequences for fishermen and people who eat fish
  • Tragedy of the Commons: a situation where individuals acting in their own self-interest can lead to a depletion of a shared resource.
• Destructive Fishing Methods


  • Bottom Trolling: dragging a net on the bottom, which can hurt the bottom habitat, destroy structures like coral reefs, and result in bycatch (catching unintended species)
• Types of Mining


  • Surface Mining: more environmentally harmful, disrupting more habitat and causing erosion in streams
  • Subsurface Mining: more expensive, has a greater human harm effect, but is another way to mine, especially for coal
• Environmental Impacts of Mining

  • Habitat loss
  • Erosion in streams
  • Acid mine drainage (when rainwater reacts with pyrite or sulfur-containing compounds, producing sulfuric acid)
  • Release of toxic metals
  • Lowering the pH of lakes and rivers, causing organisms to die
• Environmental Impacts of Urbanization

  • Disrupting habitat, soil, and vegetation
  • Changing the water cycle (more runoff, less infiltration)
  • Increasing saltwater intrusion into aquifers
  • Urban heat island effects
• Solutions to Urbanization


  • Having boundaries on urban growth
  • Mixed land use (walkable neighborhoods with entertainment, stores, and living spaces)
• Ecological Footprint


  The area of land required to keep a person's lifestyle sustainable
• Sustainability


  Living sustainably means reusing renewable resources at a rate they can replenish themselves
• Maximum Sustainable Yield


  The amount of a renewable resource that can be taken while still allowing it to renew itself
• Environmental Indicators


  • Biodiversity: The variety of species in an ecosystem
  • Food Production: The amount of food produced in an ecosystem
  • Atmospheric Temperature: The temperature of the atmosphere
  • Human Population: The number of humans in an ecosystem
  • Resource Depletion: The amount of resources being used in an ecosystem
• Ways to Reduce Urban Runoff


  • Increasing infiltration through permeable pavement, raingardens, or bioswales
  • Using green roofs or cisterns
  • Having more public transportation and building up, not out
• Integrated Pest Management


  • Using bio controls like ladybugs or beneficial insects
  • Rotating crops to disrupt pest cycles
  • Researching and monitoring to reduce pesticide use
• Benefits of Integrated Pest Management

  • Less pesticide contamination of groundwater
  • Less human exposure to pesticides
  • Less pesticide treadmill (the constant need for new pesticides)
  • Increases soil fertility