C11: The Earth's atmosphere

• The earth's atmosphere has changed composition over time
• Humans are having effects on the earth's atmosphere currently
• Nitrogen is the most abundant gas in the earth's atmosphere, making up around 78% of the air
• Oxygen is the next most abundant gas, making up around 21% of the air
• The remaining 1% of the atmosphere is made up of other gases such as carbon dioxide and argon
• The earth formed around 4.6 billion years ago and initially had an atmosphere of hydrogen and helium
• Volcanoes erupting in the early earth put large amounts of methane, ammonia, water vapour and carbon dioxide into the atmosphere
• Carbon dioxide was the most prominent gas in the early earth's atmosphere
• The formation of oceans around 3.7 billion years ago triggered the start of life, with algae producing oxygen
• Oxygen increased in the atmosphere, reacting with and removing methane and ammonia
• Nitrogen became a stable and abundant gas in the atmosphere
• Carbon dioxide became trapped in rocks and sediments, reducing its levels in the atmosphere
• Greenhouse gas

  A gas that traps heat in the atmosphere and contributes to global warming
• Carbon dioxide and methane are the two most abundant greenhouse gases in the atmosphere
• Small percentage changes in greenhouse gases can have massive effects on global temperature
• Global warming is the increase in global temperature due to the greenhouse effect
• Effects of global warming

  • Social
  • Health
  • Environmental
  • Economic
  • Political
• Burning of fossil fuels releases carbon dioxide into the atmosphere
• Burning fossil fuels also releases other pollutants like sulfur dioxide, methane, nitrogen dioxide, carbon monoxide and carbon particulates
• Sulfur dioxide

  Causes acid rain, which can damage ecosystems
• Methane


  Comes from livestock farming and is a greenhouse gas
• Nitrogen dioxide


  Can cause respiratory problems like bronchitis
• Carbon monoxide


  Toxic gas that replaces oxygen in the blood and is a greenhouse gas
• Carbon particulates


  Carcinogenic and can cause respiratory problems like asthma