Notes on Global Climate Change

  • Intro to Global Climate Change

    • Topic 9.5: Global Climate Change
    • Divided into two parts due to complexity.
    • Objective: Explain impacts of short/long-term climate changes on ecosystems.
    • Practice skill: Use data to support a hypothesis.

  • Historic Long-Term Climate Change

    • Difference between anthropogenic and natural climate change.

    • Earth's Orbital Changes

    • Eccentricity: Variations in Earth's orbit from circular to elliptical over ~100,000 years.

    • Obliquity: Axial tilt of the Earth which affects sunlight received by Northern latitudes.

    • Both contribute to Milankovitch cycles, which are periodic changes in climate.

  • Evidence of Historical Climate Change

    • Foraminifera Statues: Sediment layers containing shells indicate past temperatures based on species preferences.
    • Ice Core Analysis: Air bubbles in ice contain atmospheric snapshots, revealing historical carbon dioxide levels.
    • Oxygen Isotope Ratios: Ratio of heavy (O-18) to light oxygen (O-16) indicates temperature, with a higher presence of O-18 suggesting warmer periods.

  • Temperature and CO₂ Correlation

    • Historical temperature and CO₂ levels show strong correlation due to Milankovitch cycles.

    • Increasing CO₂ leads to more heat retention, with both being involved in a complex relationship.

    • Current CO₂ levels are the highest in 800,000 years, raising concerns about increasing global temperatures.

  • Impacts of Climate Change on Ecosystems

    • Global Warming: Average surface temperatures on the rise, leading to habitat loss.
    • Drought: Regions may experience prolonged dry spells affecting habitats and accelerating extinction rates.
    • Increased Precipitation in Certain Areas: Some regions will become wetter due to changed atmospheric conditions.
    • Soil Desiccation: Higher temperatures lead to drier soils, influencing agricultural viability.
    • Rising Sea Level: Melting ice contributes to sea level rise, affecting marine and coastal ecosystems.
    • Melting Permafrost: Leads to anaerobic decomposition producing greenhouse gases, creating a positive feedback loop.

  • Future Projections and Risks of Climate Change

    • The IPCC predicts significant ecosystem threats by a 2°C increase by 2100, including:

    • Loss or shift in ecosystems.

    • Increased extreme weather.

    • Risk of coral bleaching and coastal flooding.

    • Coastal Communities: Displacement risks due to rising sea levels; wealthier areas may adapt better.

    • Loss of Barrier Islands: Integral for protecting coastal ecosystems are at risk from inundation.

  • Impact on Atmospheric Circulation

    • Hadley Cell Changes: Expected to widen and weaken as polar regions warm more than equatorial regions, changing subtropical weather patterns.

    • Jet Stream Variability: Destabilized jet stream may lead to extreme weather patterns, as seen during the cold snap in 2014 attributed to climate change.

    • Explore maps illustrating temperature correlations in the U.S. to support hypotheses about jet stream impacts.