Study Notes on Climate Change and Global Warming (Chapter 9)

Definition of Climate: Long-term patterns or trends of meteorological conditions.
Definition of Weather: The meteorological conditions in a given place on a given day.
- Weather can vary from day to day, while climate changes more slowly.
Climate Change Definition: An alteration in the long-term patterns and statistical averages of meteorological events.
Historical Climate Trends:
- Natural global cooling and warming have occurred through history via cycles.
- Milankovitch Cycles: Cycles of approximately 100,000 years that affect Earth's climate.
- CO2 and temperature are correlated, with CO2 levels never exceeding 300 ppm over the last 420,000 years.
- Current trend shows Earth is warming, with 1976 being the last year with a cooler than average temperature.

Recent Measurements:
- Ice Cores: Used to analyze CO2 levels and temperature averages.
- Tree Cores: Provide additional historical climate data.
Earth’s Energy Budget: Three primary factors that exert substantial influence on climate:
- The Sun: Vital for Earth’s warmth and light.
- The Atmosphere: Essential for maintaining temperature and providing gases for life.
- The Oceans: Play a crucial role in heat and moisture storage and transport.
Temperature Alteration Mechanisms:
- Albedo Effect: Reflectivity of the atmosphere influencing temperature.
- Sulfate Aerosols: Result from coal burning, can cool the Earth.

Greenhouse Effect:
- Defined as the trapping of heat in the troposphere by greenhouse gases, which causes atmospheric warming.
- Key Greenhouse Gases:
  - Water Vapor
  - Carbon Dioxide (CO2): Current levels exceed 400 ppm; derived from fossil fuel burning and deforestation.
  - Methane (CH4): Released from decomposition processes and livestock, increases due to natural gas extraction and landfill emissions.
  - Nitrous Oxide (N2O): By-product of agricultural processes, burning fossil fuels, and burning forests.
  - Chlorofluorocarbons (CFCs): Synthetic greenhouse gases.
Global Warming Potential (GWP): Relative measure of how much heat a greenhouse gas traps in the atmosphere over a specific time compared to CO2.
- Examples of GWP relative to CO2 (100-year residence time):
  - CO2: GWP = 1
  - CH4: GWP varies; significantly higher than CO2.
  - N2O: GWP varies; significantly higher than CO2.
  - CFCs: GWP varies; among the highest.
Positive Feedback Loops:
- Warming triggers mechanisms like the albedo effect, leading to ice melt and further warming.

Distribution of Greenhouse Gas Production: Visual data insights (e.g., Figures 9.22 & 9.23).
Current CO2 levels are depicted in graphical form consistent with global temperature anomalies.

Impact Analysis:
- Current and future risks for the United States include:
  - Threatened water supplies due to flooding, drought, and rising sea levels.
  - Disruptions to food systems expected to increase.
  - Vulnerability of homes and property from extreme weather and sea level rise.
  - Damage to infrastructure caused by severe weather.
  - Healthcare concerns exacerbated by climate change.
Ecosystem Changes:
- Ecosystems facing transformational changes, including drier or wetter conditions.
- Increase in droughts in tropics and subtropics and more intense, frequent storms.
- Seasonal rain areas experience shorter growing seasons.
- Melting glaciers and ice sheets, over 80% globally retreating, causing sea level rise.
- Recorded seawater rise of approximately 101 mm (4 inches) since 1993.
Human Displacement: Anticipation of millions displaced from coastal areas due to flooding.
Biological and Environmental Impacts:
- Disruption of life cycles; temperature-dependent phenomena affecting migration and breeding.
- Organisms experiencing spatial shifts due to warming.
- Example: Edith's checkerspot butterfly moves 100 miles north of its historical range leading to fragmented habitats.
Health Impacts:
- Increased heat stress correlating with higher mortality rates.
- Rise in tropical diseases due to habitat changes of disease-carrying species, with specific attention to mosquitoes that can carry malaria and dengue.

Computer Simulations:
- Models indicate that action to reduce greenhouse emissions correlates with lowered future temperatures.
- Human activities significantly accelerate global warming; climate models are only accurate when incorporating human impacts (back-casting).
Intergovernmental Panel on Climate Change (IPCC):
- Overview of the 6th Assessment Report detailing findings on impacts, adaptation, and vulnerability.
- Future expectations based on model predictions include:
  - Rising temperatures between 2.5 to 10 °F over a century.
  - Prolonged frost-free seasons and altered precipitation patterns.
  - Increased incidents of drought and heatwaves.
  - Stronger hurricanes and anticipated sea level rise of approximately 3.5 to 7 ft by 2100.
  - Potential for an ice-free Arctic.

Drawdown Concept: Defines the point at which greenhouse gas levels in the atmosphere stop rising and begin to decline, thus halting climate change.
- Imbalance of Sources and Sinks: Importance of addressing both the input and output of greenhouse gases.
- Climate Solutions Overview:
  - Reducing emissions sources.
  - Supporting natural sinks that absorb CO2.
  - Enhancing societal responses and structures.

Changing Climate Conditions:
- Increased droughts and flooding associated with climate variability.
- Shifts in weather patterns impacting regional climates.

Cost and Policy Alternatives:
- Diverse strategies such as regulations, economic incentives, and international collaboration.
- Historical agreements:
  - Earth Summit (1992)
  - Kyoto Protocol (1997): Aimed to reduce emissions by 5% below 1990 levels by 2010, faced criticism for not imposing obligations on developing nations.
  - Paris Agreement (2015): Focused on global commitment to adaptation and mitigation.
Reduce personal carbon footprints: Collective decisions can drive change.
Call to Action: Emphasis on immediate action required to combat climate change effectively for future generations.