Lecture Notes: The Carbon Cycle and Climate Change

Introduction

• Focus on the link between global warming (climate change) and food production and consumption.
• Explanation of Earth's unique atmosphere and climate due to the natural greenhouse effect.

Greenhouse Gases

• Key Greenhouse Gases:
  • Carbon dioxide (CO2)
  • Methane (CH4)
  • Water vapor
  • Nitrous oxide (N2O)
• Function as a greenhouse by trapping heat from the sun, warming the planet.
• Natural greenhouse effect maintains Earth's temperature.

Increase in Greenhouse Gases

• Recent centuries have seen a substantial increase in greenhouse gases.
• More heat trapped, akin to a thicker blanket analogy.
• The term "climate change" is preferred over "global warming" due to broader implications.

Historical Climate Data

• Proxy Sources: Methods to understand past climate:
  • Ice Cores: Extracted from Antarctic and Greenland ice sheets, can show atmospheric gas levels over time.
  • Sedimentary Layers: Indicate past environments based on texture and composition.
  • Packrat Middens: Layers of collected debris can indicate historical climates.
  • Sea Floor Sediments: Analysis of cores gives insight into past ocean temperatures and conditions.
  • Coral Reefs and Tree Rings: Both can be analyzed to understand past climate conditions.

Climate Fluctuations

• Natural climate fluctuations over hundreds of thousands of years.
• Recent rapid changes are unprecedented, largely due to human activity.
• Industrial Revolution marked a significant increase in CO2 levels.

Carbon Cycle Activity

• Cellular Respiration: Releases CO2.
• Photosynthesis: Absorbs CO2.
• Fossil fuels and deforestation increase atmospheric CO2.
• Methane sources include landfills and livestock.

Consequences of Climate Change

• Glacial and Polar Ice Melting: Leading to rising sea levels.
• Sea Level Rise: Affects coastal regions, flooding, and erosion.
• Ocean Acidification: CO2 absorption leads to more acidic oceans, affecting marine life.
• Extreme Weather Events: Heatwaves, storms, and altered rainfall patterns.
• Local Impacts: Water shortages, wildfires, coastal erosion in places like San Diego.

Societal and Global Impacts

• Environmental Refugees: No existing laws to protect those displaced by climate change.
• Diseases: Changes in climate could spread tropical diseases to new areas.
• Economic and Cultural Impacts: Affect infrastructure, agriculture, and biodiversity.
• Adaptation and Mitigation: Examples like the Netherlands' dike systems and flood management.

Conclusion

• The importance of understanding the scientific basis of climate change.
• Encouragement to take action locally and globally, with resources like 360.org.
• Understanding climate change is essential for future planning and sustainability.