Global Climate Change - Lecture Notes

Introduction

• Presenter: Mr. Smeeds
• Topic: Global Climate Change (Part 1)
• Objective: Explain impacts of short and long-term climate changes on Earth's ecosystems.
• Skill Practice: Using data to support a hypothesis.

Long-term Natural Climate Change

• Earth’s Orbit Variations:
  • Eccentricity: Changes in how circular Earth's orbit is. Occurs on a roughly 100,000-year cycle.
  • Obliquity: Changes in Earth's axial tilt, affecting solar radiation and temperatures.
  • Milankovitch Cycles: Predictable 100,000-year climate cycles due to changes in Earth’s solar radiation exposure.

Evidence for Historical Climate Variability

• Foraminifera Shells: Provide temperature history based on sediment layers in ocean floors.
• Ice Core Bubbles: Contain atmospheric snapshots for carbon dioxide levels at different times.
• Oxygen Isotopes: Ratios of Oxygen-18 to Oxygen-16 indicate historical temperatures.

Current Climate Change Concerns

• Carbon Dioxide and Temperature Correlation:
  • Historically linked, but causality unclear.
  • Current CO2 levels unprecedented in 800,000 years.
  • Concern for warming due to high current CO2 levels.

Effects of Climate Change

• Global Warming: Increased average surface temperatures.

  • Habitat loss due to drying and precipitation changes.
  • Potential sixth mass extinction due to accelerated species loss.
  • Droughts and soil desiccation affecting agriculture.

• Rising Sea Levels:

  • Due to ice melt and thermal expansion.
  • Coastal communities face displacement.

• Permafrost Melting:

  • Releases methane and CO2, creating a positive feedback loop.

Climate Change Projections and Risks

• IPCC Predictions:
  • Ecosystem threats with 2°C warming by 2100.
  • Risks of extreme weather, coral bleaching, and coastal flooding.

Specific Impacts on Coastal Communities

• Displacement: Poorer communities face refugee status due to sea-level rise.
• Barrier Islands:
  • Loss leads to reduced coastal protection and habitat loss.

Atmospheric Circulation Changes

• Hadley Cell Expansion:

  • Shift due to reduced temperature differential between poles and equator.

• Polar Jet Stream Destabilization:

  • Caused by decreased temperature and pressure differences.
  • Leads to a wobbling effect, influencing weather patterns (e.g., 2014 Polar Vortex in the U.S.).

Practice FRQ 9.5

• Task: Use data to explain how a destabilized jet stream caused the 2014 cold spell in the Midwest USA.