Unit 9

• Ozone (O3)


  Formed through a specific kind of reaction: UV radiation strikes oxygen molecules (O2) and splits them into two atmospheric oxygen atoms (O), which then react with O2 to form O3 (ozone molecules)
• Ozone depletion was first discovered in 1985, and it was discovered because of a giant hole or thinning of ozone that formed over the Antarctic pole. This thinning occurs seasonally and is caused by man-made chemicals, which are anthropogenic.
• Man-made chemicals contributing to ozone depletion

  • Chlorine (Cl)
  • Fluorine (F)
  • Bromine (Br)
  • Chlorofluorocarbons (CFCs)
• Chlorofluorocarbons (CFCs) are the primary concern, as they are the major damaging component of CFCs.
• The Montreal Protocol


  Written in the 1980s to help protect stratospheric ozone from further depletion by phasing out CFCs and replacing them with other chemicals, such as hydrofluorocarbons (HFCs)
• HFCs do not cause ozone depletion, but they are strong greenhouse gases.
• The Greenhouse Effect


  A naturally occurring process that keeps our planet warm. Heat from the sun enters Earth's atmosphere and is trapped by greenhouse gases, keeping the surface of the planet warm.
• Fossil fuel combustion is the primary source of greenhouse gases.
• The Kyoto Protocol


  Addresses the greenhouse effect and aims to reduce greenhouse gas emissions worldwide.
• Common Greenhouse Gases


  • Water Vapor (H2O)
  • Carbon Dioxide (CO2)
  • Methane (CH4)
  • Nitrous Oxide (N2O)
  • Chlorofluorocarbons (CFCs)
• The result of increasing greenhouse gas emissions is global warming, which is causing various changes in climate and climate patterns.
• The graph below shows an upward trend in CO2 levels, correlating with human fossil fuel use and net destruction of vegetation.
• Positive Feedback Loops


  A feedback loop that encourages further warming, such as: Thawing of tundra permafrost, releasing methane, which is a strong greenhouse gas; Melting of ice and snow, reducing albedo (reflectivity) and allowing more heat to be absorbed.
• Examples of Positive Feedback Loops


  • Thawing of permafrost and releasing methane: As temperatures increase, permafrost thaws, releasing methane. Methane is a strong greenhouse gas, encouraging further warming.
  • Melting of ice and snow: As temperatures increase, ice and snow melt, exposing water. Water has a lower albedo than ice and snow, absorbing more heat and encouraging further warming.
• Ice melting leads to loss of primary hunting grounds for species such as polar bears. Species may move into different locations as biomes shift due to temperature increases. Tropical rainforests and savannahs are expanding north and south as temperatures rise.
• Diseases spread further north and south as species like mosquitoes move into new areas. Soil productivity changes. Ocean and wind currents shift. Increase in ice melting, leading to sea level rise. Thermal expansion of the ocean, causing ocean volume to increase.
• Ocean temperature is rising as the Earth's surface warms, leading to metabolic and reproductive changes in ocean species and coral bleaching.
• Ocean Acidification


  The decrease in the pH level of the ocean over time, caused by the absorption of carbon dioxide from the atmosphere. CO2 absorption by the ocean leads to the formation of carbonic acid, which makes it difficult for shelled organisms to build their shells.
• HIPPCO: Major factors that cause biodiversity loss

  • Habitat destruction
  • Invasive species
  • Population growth
  • Pollution
  • Climate change
  • Overexploitation of species
• Threatened species


  At high risk of extinction in the immediate future
• Endangered species


  Protected by laws such as the Endangered Species Act in the United States
• International agreements such as the CITES trade agreement help regulate the trade of animals and plants to ensure it does not harm their populations.
• Methods for Protecting Biodiversity

  • Strong legislation: Protect species through laws like the Endangered Species Act
  • Criminalize poaching: Discourage poaching by making it a criminal offense
  • Protect habitat: Preserve habitats of species and install habitat corridors
  • Reintroduction: Reintroduce species into areas where they have become extinct
  • Monitoring land use: Make land use more sustainable to reduce harm to species
  • Breeding programs: Run breeding programs through zoos and other organizations
  • Restoration of ecosystems: Restore compromised ecosystems in lost habitats
  • Reduce non-native species: Reduce the spread of non-native and invasive species that compete with specialist species