In-Depth Study Notes on Climate Change, Ozone Layer, and Biodiversity

Stratospheric Ozone

  • Function of Ozone

    • Ozone absorbs dangerous high-energy UV radiation, enabling life on Earth.
    • Formed when ultraviolet (UV) radiation strikes oxygen atoms, splitting them, which later combines with other oxygen molecules to form ozone ($O_3$).

  • Effects of UV Radiation

    • Causes sunburn, skin cancer, and eye cataracts.

  • Ozone Depletion

    • Thinning of the ozone layer first identified in 1985, primarily caused by human-made chemicals containing halogens (chlorine, fluorine, bromine).
    • Chlorofluorocarbons (CFCs) are major contributors, found in aerosols and refrigerants.
    • CFCs break down in the atmosphere, releasing chlorine, which reacts with ozone, leading to further depletion ($ClO + O3 \rightarrow Cl + 2O2$).

  • Montreal Protocol (1987)

    • An agreement to phase out ozone-depleting substances, especially CFCs and replacing them with less harmful chemicals like HFCs, although HFCs are strong greenhouse gases (GHGs).

Greenhouse Gas Effect

  • Basic Mechanism

    • Sunlight hits Earth's surface; some is reflected back to space as infrared (IR) radiation.
    • Greenhouse gases absorb some IR radiation and trap heat in the atmosphere, which is necessary for maintaining life.
    • Excessive greenhouse gas emissions are a major cause of climate change.

  • Human-Made Greenhouse Gases

    • Major source is from fossil fuel combustion.
    • Common GHGs include CO₂ (carbon dioxide), CH₄ (methane), CFCs, and NOₓ (nitrogen oxides).

  • Kyoto Protocol

    • International agreement aimed at reducing greenhouse gas emissions on the basis that climate change results from human activity.

Global Warming and Feedback Loops

  • CO₂ Trends

    • CO₂ levels have been rising consistently due to human activity (combustion of fossil fuels and deforestation).
    • Seasonal CO₂ variation exists, but overall levels trend upward.

  • Temperature Changes

    • The earth's temperature has increased unevenly, with extreme northern latitudes experiencing the most significant increases ($1-4$ degrees Celsius).

  • Feedback Loops

    1. Permafrost Thawing
    • Rising temperatures lead to the thawing of tundra permafrost, releasing more CO₂ and CH₄, exacerbating global warming.
    1. Albedo Effect
    • Ice and snow reflect sunlight (high albedo), but as they melt, darker water reflects less, heat absorption increases, worsening warming.

Effects of Climate Change

  • Ecosystem Impact

    • Changes in habitat lead to species migration (e.g., polar bears losing hunting grounds) and the spread of diseases from tropical areas.

  • Ocean Changes

    • Sea levels rise due to thermal expansion and melting ice, affecting coastal habitats.
    • Ocean acidification occurs due to increased CO₂ levels, creating carbonic acid ($CO2 + H2O \rightarrow H2CO3$), which dissolves carbonate needed for shell formation.

  • Coral Bleaching

    • Increased temperatures lead to coral bleaching, where corals expel the algae that live symbiotically with them, turning them white and causing stress to the ecosystem.

Human Impact on Biodiversity (HIPPCO)

  • Human Activities
    • H: Habitat destruction (urbanization, deforestation).
    • I: Invasive species outcompeting native species.
    • P: Overpopulation leading to resource strain.
    • P: Pollution of air and water bodies.
    • C: Climate change altering habitats.
    • O: Overexploitation of resources (like poaching and overfishing).

Conservation and Preservation Efforts

  • Legislation

    • CITES: Regulates animal and plant trade to prevent population decline.
    • Endangered Species Act: Lists and protects threatened and endangered species.

  • Conservation Strategies

    • Establishing conservation areas, habitat corridors, and reintroduction programs for species like the gray wolf.
    • Implementing breeding programs and restoring ecosystems.
    • Reducing the impact of invasive species on native wildlife.