AP Environmental Science Unit 9: Global Change

Stratospheric Ozone

• Good Ozone (O3): Absorbs UV radiation, protecting from sunburn, skin cancer, and eye damage.
• Formation: UV radiation splits O2 into single O atoms, which react with O2 to form O3.
• Ozone Depletion:
  • Discovered in 1985 as a seasonal hole at the Antarctic pole.
  • Caused by anthropogenic chemicals like CFCs (chlorofluorocarbons).
  • Chlorine from CFCs reacts with O3, breaking it down.

Montreal Protocol

• International treaty to phase out substances like CFCs to protect the ozone layer.
• Replacements like HFCs do not deplete ozone but are potent greenhouse gases.

Greenhouse Effect and Gases

• Natural Phenomenon: Keeps Earth's surface warm by trapping infrared heat.
• Greenhouse Gases: CO2, water vapor, methane, N2O, and CFCs.
• Human Contribution: Primarily from fossil fuel combustion.
• Kyoto Protocol: International agreement to reduce greenhouse gases.

Global Warming

• Gases' Warming Potential:
  • Methane and CFCs have higher warming potential than CO2.
  • CO2 levels fluctuate seasonally but show an upward trend due to fossil fuel use and deforestation.
• Temperature Trends: Not uniform globally; more pronounced warming in polar regions due to feedback loops.

Positive Feedback Loops

• Thawing Tundra: Releases methane, enhancing warming.
• Ice-Albedo Effect: Melting ice reduces reflectivity, increasing heat absorption.

Climate Change Effects

• Habitat Loss: Melting ice affects species like polar bears.
• Species Migration: Shift of species north/south due to temperature changes.
• Disease Spread: Warmer climates allow tropical diseases to spread.
• Soil and Ocean Changes: Affect productivity and currents.
• Sea Level Rise: Due to ice melt and thermal expansion of oceans.
• Ocean Acidification: CO2 absorption forms carbonic acid, reducing carbonate for shelled organisms.

Biodiversity Concerns

• HIPPCO Factors: Habitat destruction, Invasive species, Population, Pollution, Climate change, Over-exploitation.
• Threatened Species: Often specialists, affected by human actions.
• Conservation Laws:
  • Endangered Species Act: Protects U.S. species.
  • CITES: Regulates international wildlife trade.

Biodiversity Protection Methods

• Legislation and Enforcement: Prevents poaching and habitat destruction.
• Habitat Corridors: Connect fragmented habitats.
• Reintroduction Programs: E.g., gray wolves in Yellowstone.
• Sustainable Land Use, Breeding Programs, and Invasive Species Control.

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