Comprehensive Notes on Global Change

Unit 9: Global Change

Overview

• This unit focuses on global environmental changes, their causes, and consequences.
• Students should build on previous skills to propose solutions to environmental problems.
• Emphasis on using data as evidence to support proposed solutions or legislation and explaining how these address the problem.

Preparing for the AP Exam

• Common Struggle: Discussing strategies to prevent extinction.
  • Students can identify strategies but fail to explain their implementation.
  • Incorrectly assuming small populations are always threatened.
  • Solution: Provide multiple sources for students to propose realistic solutions.
  • Opportunities to explain advantages, disadvantages, and unintended consequences of extinction prevention efforts.
• Confusion: Global climate change vs. ozone depletion.
  • Solution: Practice using scientific vocabulary in the correct context.
  • Use diagrams and models to illustrate global climate change.
  • Emphasize the effects of global climate change with visual representations of changes over time.

Building Understanding

• A central aspect is understanding the global impact of local and regional human activities.
• Humans can mitigate impact through sustainable use of resources.
• Human activities cause ozone depletion in the stratosphere and increase greenhouse gases.
• Increased greenhouse gases lead to human health and environmental problems like global climate change, ocean warming, and endangered species.
• The course examines interrelationships in the natural world and challenges students to evaluate and propose solutions.

Big Ideas

• Interactions: Interactions between different species and the environment. Why are laws created to protect endangered species?
• Sustainability: How can local human activities have a global impact?

Unit 9 Topics

• 9. 1 Stratospheric Ozone Depletion
• 9. 2 Reducing Ozone Depletion
• 9. 3 The Greenhouse Effect
• 9. 4 Increases in the Greenhouse Gases
• 9. 5 Global Climate Change
• 9. 6 Ocean Warming
• 9. 7 Ocean Acidification
• 9. 8 Invasive Species
• 9. 9 Endangered Species
• 9. 10 Human Impacts on Biodiversity

Sample Activities

• 9.8 Ask the Expert: Divide students into groups to become experts on invasive species case studies (e.g., zebra mussels, cane toad, black rats). Groups rotate to share knowledge.
• 9.10 Debate: Scenario: Proposal to construct a new mall in a wetland estuary. Divide the class into two teams, one arguing that biodiversity will not be affected and the other arguing that it will. Focus on the impact of the eliminated waterway.

9.1 Stratospheric Ozone Depletion

• Learning Objective: Explain the importance of stratospheric ozone to life on Earth.
• Essential Knowledge:
  • The stratospheric ozone layer is crucial for the evolution and survival of life on Earth.
  • Stratospheric ozone depletion is caused by anthropogenic factors (CFCs) and natural factors (melting ice crystals in Antarctic spring).
  • Decreased stratospheric ozone increases UV rays reaching the Earth's surface, leading to skin cancer and cataracts.

9.2 Reducing Ozone Depletion

• Learning Objective: Describe chemicals used to substitute for chlorofluorocarbons (CFCs).
• Essential Knowledge:
  • Ozone depletion can be mitigated by replacing ozone-depleting chemicals with substitutes.
  • Hydrofluorocarbons (HFCs) are replacements, but some are strong greenhouse gases.

9.3 The Greenhouse Effect

• Learning Objective: Identify the greenhouse gases.
• Essential Knowledge:
  • Principal greenhouse gases: carbon dioxide, methane, water vapor, nitrous oxide, and chlorofluorocarbons (CFCs).
  • Water vapor has a short residence time and doesn’t significantly contribute to global climate change.
  • The greenhouse effect results in the surface temperature necessary for life on Earth.

9.4 Increases in the Greenhouse Gases

• Learning Objective: Identify the sources and potency of the greenhouse gases.
• Essential Knowledge:
  • Carbon dioxide (GWP = 1) is the reference point for comparing greenhouse gases.
  • CFCs have the highest GWP, followed by nitrous oxide, then methane.
• Learning Objective: Identify the threats to human health and the environment posed by an increase in greenhouse gases.
• Essential Knowledge:
  • Global climate change can lead to rising sea levels, melting ice sheets, ocean water expansion and disease vectors spreading.
  • These problems can lead to changes in population dynamics and movements.

9.5 Global Climate Change

• Learning Objective: Explain how changes in climate, both short- and long-term, impact ecosystems.
• Essential Knowledge:
  • Earth has undergone climate change throughout geologic time, recorded in $CO_2$ data and ice cores.
  • Effects include rising temperatures, melting permafrost and sea ice, rising sea levels, and displacement of coastal populations.
  • Marine ecosystems are affected by changes in sea level (positively and negatively).
  • Winds and oceanic currents transport heat; climate change may alter circulation patterns (Hadley cells, jet stream).
  • Climate change affects soil temperature and rainfall, impacting its viability and increasing erosion.
  • Polar regions show faster response times due to positive feedback loops.
  • Melting ice and snow reduce energy reflected back to space, causing more warming.
  • Arctic response time is due to melting sea ice, thawing tundra, and release of methane.
  • Loss of ice and snow affects species dependent on ice for habitat and food.

9.6 Ocean Warming

• Learning Objective: Explain the causes and effects of ocean warming.
• Essential Knowledge:
  • Ocean warming is caused by increased greenhouse gases.
  • Ocean warming affects marine species through habitat loss and metabolic/reproductive changes.
  • Ocean warming causes coral bleaching (loss of algae).

9.7 Ocean Acidification

• Learning Objective: Explain the causes and effects of ocean acidification.
• Essential Knowledge:
  • Ocean acidification is the decrease in pH due to increased $CO_2$ concentrations: can be expressed as chemical equations.
  • Oceans absorb $CO_2$, becoming more acidic.
  • Anthropogenic activities lead to increased $CO_2$ (burning fossil fuels, vehicle emissions, deforestation).
  • Ocean acidification damages coral by making it difficult to form shells (loss of calcium carbonate).

9.8 Invasive Species

• Learning Objective: Explain the environmental problems associated with invasive species and strategies to control them.
• Essential Knowledge:
  • Invasive species thrive outside their normal habitat.
  • Considered invasive when they threaten native species.
  • Often generalist, r-selected species that outcompete native species.
  • Controlled through human interventions.

9.9 Endangered Species

• Learning Objective: Explain how species become endangered and strategies to combat the problem.
• Essential Knowledge:
  • Factors leading to endangerment: hunting, limited diet, invasive species, specific habitat requirements.
  • Species adapt to changes/move to new environments are less likely to face extinction.
  • Selective pressures change behaviors and fitness.
  • Species compete for resources, leading to endangerment/extinction.
  • Strategies: criminalizing poaching, protecting habitats, legislation.

9.10 Human Impacts on Biodiversity

• Learning Objective: Explain how human activities affect biodiversity and strategies to combat the problem.
• Essential Knowledge:
  • HIPPCO (habitat destruction, invasive species, population growth, pollution, climate change, and over exploitation) decreases biodiversity.
  • Habitat fragmentation: large habitats broken into smaller areas (roads, agriculture, development, logging).
  • Scale of habitat fragmentation varies for each species.
  • Global climate change causes habitat loss (temperature, precipitation, sea level rise).
  • Domestication can negatively impact biodiversity.
  • Mitigation: protected areas, habitat corridors, sustainable land use, restoring habitats.