Climate 5/5

5. Greenhouse effect and climate change

  • Earth’s atmosphere is a thin layer of gasses that surround the Earth

  • Greenhouse gasses are gasses in the atmosphere that absorb heat energy

    • The amount of water vapor in the atmosphere is variable so it is usually is omitted from greenhouse gas estimates

      • Deserts have very little while tropical rainforests have lots

    • These gasses cause the greenhouse effect because they absorb energy by trapping it in the atmosphere

      • The natural greenhouse effect is good

        • It makes the earth warm enough for life (16 degrees celsius rather than -15 degrees celsius)

      • The enhanced greenhouse effect is bad

        • The concentration of greenhouse gasses in the atmosphere has increased

        • More greenhouse gasses trap more heat energy in the atmosphere, which makes the air temperature warmer

        • More carbon compounds (CO2 and CH4) are entering the atmosphere than are exiting

    • Some gasses are more potent than others (they can hold more heat energy)

    • The source of excess greenhouse gasses

      • Human activities increase greenhouse gasses in the atmosphere

    • The source of excess carbon dioxide

      • Burning fossil fuels for energy

      • Forest fires and other burning

      • Deforestation

    • Effects of excess greenhouse gasses

      • Enhcnace greenhouse effect, which causes global warming, which causes climate change

      • The average temperature of the atmosphere has increased by 1.4 degrees celsius from 1880 to 2023

    • Effects of global warming

      • Melting glaciers and ice caps

        • Damages habitats

        • Adds water to oceans which raises the sea level

      • Rising sea levels causes flooding of islands and coastal areas

        • Melting glaciers increase the volume of water

        • Thermal expansion of water in warmer temperatures

      • Melting permafrost in tundra

        • Houses, roads, and trees (drunken trees) sink

        • Increased methane production with rotting vegetation and release of methane stores

      • Changes in climate

        • Changing weather patterns: some areas get more rain than usual while others get less

        • More severe storms due to excess energy in the atmosphere

        • Increased drought

        • Increase flooding

        • More severe weather

      • More forest fires

    • Changes in temperatures and precipitation cause the range of some biomes to shift

    • Living things are greatly affected

      • Plants and animals are adapted to their climate of their biome

      • When climate change is gradual, populations have time to adapt to the changing environment or move to another location

      • When climate change is rapid, there is little time for evolution or relocation, therefore extirpation and extinction may occur

      • Polar bears need ice to hunt for seales

        • Receding polar ice caps cause many to starve

    • Evidence for global warming and climate change

      • Analyzing ice cores provides information about past climate

        • Gasses trapped in air spaces indicate levels of greenhouse gasses

        • Types of crystal formed indicate temperatures when ice formed

      • Analyzing tree rings provides information about past climate:

        • Wider rings indicate much rainfall and narrow rings indicate drought

        • Black soot indicates forest fire

      • Fossil evidence:

        • The type of organisms that lived in specific areas in the past indicate the climate since it must be conditions that support the life of these organisms

        • Example: pollen in ice cores, plant and animal fossils

      • A network of measurement stations collects data on temperature and atmospheric gasses throughout the year

        • Earth’s temperature has always fluctuated but during the last 100 years, temperature has risen more than ever

Greenhouse gas concentration has increased in the past 100 years. Throughout time, there has been a correlation between global temperature and atmospheric CO2