CGP - Water & Carbon cycle

• System


  Made up of stores, flows, boundaries, inputs and outputs
• You need to learn what these parts of a system are
• Inputs

  • When matter or energy (e.g. solar energy) is added to the system
• Outputs

  • When matter or energy leaves the system
• Stores or components


  • Where matter or energy builds up
• Flows or transfers


  • When matter or energy moves from one store to another
• Boundaries

  • The limits of the system
• Drainage basin system


  • Water enters as rain (input), the watershed is the boundary, water is stored in soil and vegetation, water travels to the river and down to the sea (output)
• Open systems

  Both energy and matter can enter and leave the system
• Closed systems


  Matter cannot enter or leave the system, but energy can
• Isolated systems (neither matter nor energy can enter or leave) are not found in nature
• In a closed system, matter can only cycle between stores, but energy can enter and leave
• The carbon cycle is an example of a closed system
• Dynamic equilibrium


  Small variations in inputs and outputs are balanced on average, so the system remains stable overall
• Positive feedback


  Mechanisms that amplify the effects of changes, moving the system further from its previous state
• Positive feedback


  • Less ice reflecting sunlight means more heat absorbed, leading to further ice melt
• Negative feedback


  Mechanisms that counteract the effects of changes, keeping the system closer to its previous state
• Negative feedback

  • Increased CO2 in the atmosphere causes plants to grow more, removing more CO2
• Subsystems of the Earth

  • Cryosphere
  • Hydrosphere
  • Lithosphere
  • Biosphere
  • Atmosphere
• The Earth system is a cascading system where changes in one subsystem can affect the others
• Matter (e.g. water, carbon) and energy move between the subsystems