3.1.1.3 the carbon cycle

• lithosphere - 99.9% sedimentary rocks
• hydrosphere - 2nd largest carbon store

  • co2 dissolves into ocean
  • 0.04%
  • phytoplankton photosynthesise
• biosphere - 0.004%
• cryosphere - permaforst 0.01%
• Photosynthesis

  1. Living organisms convert Carbon Dioxide from the atmosphere and Water from the soil, into Oxygen and Glucose using Light Energy

  2. Removes CO2 from the atmosphere
• Combustion (Burning fossil fuels, wildfires etc.)


  Releases CO2 into the atmosphere
• Decomposition


  1. When living organisms die, they are broken down by decomposers which respire, returning CO2 into the atmosphere

  2. Some carbon is also returned to the soil
• Diffusion


  The oceans can absorb CO2 from the atmosphere, but this harms aquatic life by causing coral bleaching
• Weathering and Erosion


  Rock particles broken down and transferred to the ocean, where the carbon> create shells
• Burial and Compaction


  Sea shell fragments become compacted > form limestone and organic matter may form fossil fuels
• Carbon Sequestration


  Transfer of carbon from the atmosphere and can be both natural and artificial
• Main Carbon Stores (In order of magnitude):

  • Marine Sediments and Sedimentary Rocks - Lithosphere - Long-term
  • Oceans - Hydrosphere - Dynamic
  • Fossil Fuel Deposits - Lithosphere - Long-term but currently dynamic
  • Soil Organic Matter - Lithosphere - Mid-term
  • Atmosphere - Dynamic
  • Terrestrial Plants - Biosphere - Mid-term but very dynamic
• The lithosphere is the main store of carbon

  • with global stores unevenly distributed.
  • the oceans are larger in the southern hemisphere,
  • storage in the biosphere mostly occurs on land.
  • Terrestrial plant storage is focussed in the tropics and the northern hemisphere.
• The Carbon Budget is the balance between carbon inputs and outputs to a store at any scale
• Carbon Source - A store that emits more carbon than it absorbs: E.g. a damaged rainforest
• Carbon Sink - A store that absorbs more carbon than it emits: E.g. a virgin rainforest