Carbon dioxide and methane as greenhouse gases

• Greenhouse gases


  Maintain temperatures on earth high enough to support life
• Greenhouse gases


  • Water vapour
  • CO2
  • CH4
• Greenhouse gas effect


  1. Electromagnetic radiation at most wavelengths from the sun passes through the Earth's atmosphere

  2. The Earth absorbs some radiation and warms up

  3. Some heat is radiated from the Earth as infrared radiation

  4. Some of this IR radiation is absorbed by greenhouse gases in the atmosphere

  5. Atmosphere warms up leading to the greenhouse effect and global warming
• Human activities increase levels of CO2 & CH4
• Human activities that increase greenhouse gases

  • Driving (CO2)
  • Consuming electricity (CO2)
  • Raising livestock (cows - CH4)
  • Decay of organic waste in landfill sites (CH4)
• Based on peer-reviewed evidence, many scientists believe that human activities will cause the temperature of the Earth's atmosphere to increase at the surface and that this will result in global climate change
• It is difficult to model such complex systems as global climate change, leading to simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and which may be biased
• Global climate change


  • An increase in average global temperature is a major cause
  • Potential effects include extinction of species, raising sea levels, migration, and decrease in crop yield
• Carbon footprint


  The total amount of CO2 and other greenhouse gases emitted over the full life cycle of a product, service or event
• Reducing carbon footprint


  Reducing emissions of carbon dioxide and methane e.g. by using less electricity, reducing travel or transportation, and planting more trees
• Action to reduce carbon footprint may be limited because it's more difficult, can be more expensive and planting trees takes away land that could be used to grow crops