IB DP Biology: SL复习笔记4.2.8 Skills: Carbon Cycling & Climate Change

Drawing the Carbon Cycle

  • The many processes by which carbon is transferred from one store to another are collectively known as the carbon cycle
    • During the carbon cycle, carbon is present in both organic and inorganic forms
      • Organic carbon is found in the biomass of living organisms e.g. in carbohydrates and proteins
      • Inorganic carbon is found in the atmosphere as carbon dioxide and in the oceans as e.g. hydrogen carbonate ions
  • The carbon cycle can be represented using a diagram
    • Carbon cycle diagrams show:
      • Carbon stores, known as pools, e.g the ocean, fossil fuels, or living organisms
      • Processes of carbon transfer, known as fluxes e.g. dissolving, combustion, or photosynthesis
  • Diagrams can be illustrated, or can be simple, containing just text boxes and arrows
  • Diagrams can show terrestrial carbon cycling, marine carbon cycling, or both combined in one diagram


An illustrated carbon cycle diagram showing both terrestrial and marine cycling


A simple carbon cycle diagram showing terrestrial carbon cycling

Estimation of Carbon Fluxes

  • The processes by which carbon is transferred from one pool to another are known as fluxes
  • Fluxes can be measured quantitatively, showing how much carbon is transferred by a particular process
  • The unit for carbon fluxes is gigatonnes, or GT
    • One gigatonne is a billion tonnes
  • It is difficult to measure global carbon fluxes precisely, but scientists can make estimates by measuring smaller ecosystems and scaling these measurements up

Estimated Global Yearly Carbon Fluxes Table


  • Estimating carbon fluxes is very important as humans seek to predict the impacts of climate change and reduce carbon emissions
    • By calculating the total carbon fluxes that remove carbon from the atmosphere and the total carbon fluxes that add carbon into the atmosphere scientists can calculate atmospheric carbon increases
    • This enables scientists to predict levels of atmospheric warming