Chemistry of the Atmosphere

• The earth's atmosphere is composed of about 80% nitrogen, 20% oxygen, and less than 1% of other gases like carbon dioxide, water vapor, and noble gases
• How the earth's atmosphere evolved

  1. Volcanic activity produced CO2, water vapor, nitrogen, methane, ammonia

  2. Water vapor condensed into oceans, allowing CO2 to dissolve

  3. Algae and plants evolved, using CO2 for photosynthesis and producing O2

  4. Organic matter from dead algae/plants became buried and formed sedimentary rocks, oil, and gas
• As algae and plants photosynthesized

  Atmospheric CO2 levels declined while O2 levels increased
• More complex life like animals could evolve due to the increased O2 levels
• Types of sedimentary deposits formed from buried organic matter

  • Crude oil and natural gas (from dead plankton)
  • Coal (from dead plant material)
  • Limestone (from marine organism shells and skeletons)
• Global warming

  The increase in the Earth's average surface temperature due to the greenhouse effect
• Climate change

  The long-term changes in weather patterns across the entire planet
• Greenhouse effect

  1. Sun's heat energy passes through atmosphere

  2. Some energy absorbed by Earth's surface

  3. Most energy re-emitted as longer wavelength radiation

  4. Greenhouse gases absorb and re-emit this energy in random directions

  5. Heat energy stays close to Earth
• Greenhouse gases

  • Carbon dioxide
  • Methane
  • Water vapor
• Increasing greenhouse gas concentrations

  Stronger greenhouse effect and global warming
• Causes of increasing carbon dioxide levels

  • Burning of fossil fuels
  • Deforestation
• Causes of increasing methane levels

  • Emissions from farm animals
  • Decomposition of waste
• Global warming

  Leads to climate change
• Consequences of climate change

  • More common and severe droughts, hurricanes, floods
  • Sea level rise due to ice melt and water expansion
  • Impacts on biodiversity and species survival
• Carbon footprint


  The total amount of carbon dioxide and other greenhouse gases that are emitted over something's entire life cycle
• Carbon footprints


  • They are hard to measure
  • They can help identify the most polluting activities and try to reduce their emissions
• Measuring carbon footprints


  1. Consider raw materials sourcing

  2. Manufacturing process

  3. Total power usage over lifetime

  4. Disposal

  5. Emissions from transportation
• A rough calculation can still give a good idea of which things are the worst emitters and allow us to compare them
• Ways to reduce emissions

  • Use renewable energy sources like wind, solar or nuclear
  • Use more efficient manufacturing processes
  • Reduce waste
  • Carbon capture technology
• Renewable energy is often more expensive than fossil fuels


  Makes it hard to change
• Entire economy is based on fossil fuels


  Makes it hard to change
• Governments prioritize the environment


  Whole economy might suffer
• International agreements to reduce emissions


  Difficult because no country wants to agree to anything that might hurt its economy
• Every individual needs to be responsible for their own consumption and be willing to make changes to their lifestyle if we're going to have any hope of averting the worst effects of climate change