Case studies: causes of change in the carbon cycle

• Where is permafrost found?


  places where average annual temperature is below -5 degrees celcius, includes most of arctic and Antarctica
• What would occur if there was a mass melting of permafrost?

  contribute to rising sea levels and accelerate global warming by releasing greenhouse gases into the atmosphere
• What will happen to the soil if the arctic tundra begins to thaw?

  it is rich in organic material which will decay to release methane and co2
• What might thawing permafrost result in?

  positive feedback loop
• How might the green wall in the Sahel region have a positive impact on the carbon budget?

  • reduces desertification
  • agricultural extension
  • forestry - increases the store of carbon above and below ground, with newly accumulated biomass
• How does cattle farming in Brazil have a negative impact on the carbon budget?

  • Nearly 80% deforested areas in brazil is used for pasture
  • 1996-2006 an area the size of Portugal was carved out for cattle ranching
  • forest clearance reduces intake of carbon by photosynthesis
• How has farming led to forest fires in brazil?


  Pastures are surrounded by undisturbed areas of Amazon rainforest - droughts since 2005 due to disruption to conventional rainfall - tinder dry conditions lead to fires
• How does soil erosion have a negative impact on the carbon budget?

  over cultivation, depletes nutrients, vegetation cannot grow - reduces carbon store
• Other ways that lead to forest fires?

  slash and burn in Indonesia and the Amazon