Study Notes on Global Climate Change

Chapter Overview

  • Lecture Objectives- Describe Earth’s climate system and explain the factors influencing global climate.

    • Identify greenhouse gases and characterize human influences on the atmosphere and climate.

    • Summarize how researchers study climate.

    • Outline current and expected future trends and impacts of climate change globally and in the United States.

    • Suggest and assess ways we may respond to climate change.

Our Dynamic Climate

  • Definition of Climate

    • Climate refers to an area’s long-term atmospheric conditions, including:

    • Temperature

    • Precipitation

    • Wind

    • Humidity

    • Barometric pressure

    • Solar radiation

  • Global Climate Change

    • Refers to changes in temperature, precipitation patterns, and the frequency/intensity of storms worldwide.

    • Global Warming specifically refers to an increase in Earth’s average temperature, which is just one aspect of climate change.

Factors Influencing Climate

  • Three Primary Factors 1. The Sun

    • Provides light and warmth, the primary source of energy for the Earth.

    1. The Atmosphere

    • Acts as a thermal blanket, preventing significant temperature swings between day and night.

    1. The Oceans

    • Store and transport heat and moisture, significantly affecting climate patterns.

Greenhouse Gases

  • Definition

    • Atmospheric gases with three or more atoms tend to absorb infrared radiation emitted from Earth's surface and re-emit it back downward.

    • Key greenhouse gases include:

    • Water vapor (H₂O)

    • Ozone (O₃)

    • Carbon dioxide (CO₂)

    • Nitrous oxide (N₂O)

    • Methane (CH₄)

    • Halocarbons

  • Greenhouse Effect

    • The warming of the lower atmosphere caused by the re-emission of infrared energy from greenhouse gases.

    • Global Warming Potential (GWP)

    • A measure of how much heat a greenhouse gas traps in the atmosphere compared to CO₂ (which has a GWP of 1).

    • Methane GWP = 84 times more potent than CO₂ over 20 years.

Greenhouse Gas Concentrations

  • Rising Concentrations - Over 250 years, human activities (especially fossil fuel combustion) have increased greenhouse gas levels.

    • Fossil Fuel Combustion

    • Transfers carbon from underground reservoirs to the atmosphere.

    • Deforestation

    • Reduces the biosphere’s ability to assimilate CO₂.

    • Nitrous Oxide

    • Increased due to vehicle emissions, agriculture, and fertilizers.

    • Tropospheric Ozone

    • Increased due to photochemical reactions in urban areas.

Aerosols and Climate Feedback

  • Aerosols

    • Microscopic droplets in the atmosphere can influence climate by either warming (black carbon aerosols) or cooling effects (sulfate aerosols).

  • Climate Feedback Mechanisms

    • Enhanced evaporation may lead to more water vapor (positive feedback) or increased cloud cover (negative feedback), impacting climate predictions.

Studying Climate Change

  • Ice Core Analysis - Ice caps and glaciers are drilled to study trapped air bubbles, revealing atmospheric conditions over 800,000 years.

  • Keeling Curve - Charles Keeling began measuring CO₂ levels in 1958 at Mauna Loa; levels have risen from 315 ppm to over 400 ppm today.

Current and Future Trends and Impacts

  • Trends in Climate Change 1. Rising Temperatures

    • Average surface temperatures have risen approximately 1.1°C over the last century.

    • Regions are experiencing over 1°F increase in the last two decades in the U.S.

    1. Changing Precipitation

    • Worldwide precipitation has increased by 2% over the past century, with regional variations.

    • Extreme weather events have doubled since 1970 in the U.S.

    1. Melting Ice

    • Tropical glaciers are disappearing; polar ice sheets are rapidly melting, risking a 3m rise in sea levels.

    1. Acidification of Oceans

    • Increased CO₂ in oceans makes seawater more acidic, affecting marine life reliant on calcium carbonate.

    1. Effects on Organisms and Ecosystems

    • Species migration, altered breeding times, and habitat changes are observed due to climate shifts.

    1. Socioeconomic Impacts

    • Increased health hazards such as heat waves, respiratory issues, and expanded tropical disease ranges motivate humanitarian and geopolitical challenges, pushing some to become refugees.

Addressing Climate Change

  • Mitigation Efforts - Strategies include improving energy efficiency, utilizing renewable energy, and protecting forest ecosystems.

  • Adaptation Strategies - Includes measures such as improved infrastructure (e.g., Miami Beach pump systems) and developing heat-resistant agricultural practices.

Transportation and Energy Solutions

  • Transportation - Alternatives to personal vehicles such as hybrids or public transit can significantly reduce emissions.

  • Electricity Generation - Focus on technologies to improve efficiency and switch to low-pollution sources of energy to mitigate emissions from this sector trending high.

    • Carbon Capture and Storage (CCS)

    • Technologies are needed to effectively remove and store CO₂ emissions, still not adequately scalable.

Climate Agreements and Policies

  • Kyoto Protocol - Established in 1997, aimed to enforce emission reductions; however, not ratified by the U.S.

    • 2015 Paris Agreement saw nations make serious commitments towards climate initiatives.

  • Local Initiatives - Cities and states are implementing climate policies aiming to meet or exceed Kyoto guidelines, with particular emphasis on California’s aggressive targets.

Challenges of Emission Cuts

  • Concerns exist about economic impacts of emissions restrictions; however, renewable energy has proven economically beneficial in countries like China and Germany.

Personal Responsibility in Climate Action

  • Individual actions such as energy-efficient appliance use and lifestyle choices play a crucial role in reducing carbon footprints.