AP Environmental Science Unit 9: Global Change

Key Topics

• Climate Change & Global Warming
• Biodiversity Issues
• Stratospheric Ozone & Ozone Depletion
• Greenhouse Gases & Effects
• Ocean Warming & Acidification
• Biodiversity Concerns & Protection

Stratospheric Ozone

• Function: Absorbs UV radiation to protect against sunburn, skin cancer, eye damage.
• Formation: UV radiation splits O2 molecules, forming O3 (ozone).
• Ozone Depletion:
  • Discovered in 1985; seasonal thinning over Antarctica.
  • Caused by man-made chemicals, particularly chlorine from CFCs.
  • Montreal Protocol: Phased out CFCs to protect ozone.
• Impact: Protects life from UV damage.

Greenhouse Gases & the Greenhouse Effect

• Natural Phenomenon: Keeps Earth warm by trapping infrared heat.
• Anthropogenic Causes: Mainly from fossil fuel combustion.
• Kyoto Protocol: International agreement to reduce greenhouse gases.
• Common Greenhouse Gases:
  • Water vapor, CO2, methane, nitrous oxide, CFCs
  • Each has different warming potential and atmospheric lifetime.
• Consequences: Global warming, climate change, habitat loss.

Climate Change Effects

• Global Warming: Uneven temperature changes; CO2 levels rising.
• Feedback Loops:
  • Melting permafrost releases methane, enhancing warming.
  • Ice melt reduces albedo, increasing heat absorption.
• Consequences:
  • Loss of habitat (e.g., polar bears)
  • Species migration, disease spread, soil changes
  • Ocean & wind current shifts, sea level rise

Ocean Warming & Acidification

• Ocean Warming:
  • Caused by greenhouse gases; high heat capacity of water.
  • Effects: Metabolic changes in species, coral bleaching.
• Ocean Acidification:
  • Caused by CO2 absorption, forming carbonic acid.
  • Affects carbonate availability for shell-building organisms.

Biodiversity Concerns

• HIPPCO: Factors affecting biodiversity:
  • Habitat destruction, Invasive species, Population (human), Pollution, Climate change, Over-exploitation.
• Threatened/Endangered Species:
  • High extinction risk; often specialists outcompeted by invasives.
• Laws & Agreements:
  • Endangered Species Act: Protects habitats in the U.S.
  • CITES: Regulates international trade to protect species.

Methods for Protecting Biodiversity

• Legislation & Protection: Strong laws, habitat protection, corridors.
• Reintroduction & Breeding Programs: E.g., Yellowstone wolves.
• Sustainable Land Use: Monitor and restore ecosystems.
• Invasive Species Control: Reduce non-native competition.

Note: This summary is based on the lecture by Mrs. Williams of Science Panda.