8.1.1
Carbon Stores
Introduction to the Carbon Cycle
Introduction to the Carbon Cycle
The carbon cycle plays a key role in balancing the Earth's systems. Carbon is stored in the atmosphere, on land, and in oceans, and is moved between these by various processes.
The carbon cycle
The carbon cycle
- There are no inputs or outputs in the carbon cycle. It is a closed system with three parts:
- Stores - Where carbon is held.
- Fluxes - The flows of carbon between different stores. Fluxes differ in size.
- Processes - The physical ways in which carbon fluxes happen.
Carbon stores
Carbon stores
- Carbon stores are measured in petagrams of carbon (PgC).
- The hydrosphere (38,000 PgC) - dissolved carbon dioxide in bodies of water.
- The lithosphere (100,000 PgC)- rocks like calcium carbonate and fossil fuels.
- The biosphere (2,000 PgC) - animals and plants (dead and living).
- The atmosphere (750 PgC) - gases like carbon dioxide.
Biochemical Carbon Stores
Biochemical Carbon Stores
Carbon is found across our world in different forms: as a liquid (i.e. dissolved in bodies of water), as a gas (e.g. carbon dioxide) and as a solid (i.e. calcium carbonate).
Terrestrial
Terrestrial
- Carbon is found within every living organism on the planet. On the land, every plant and animal is an example of a carbon store.
- When plant and animal matter decays, it can be converted into other carbon stores by going into the soil.
- Other terrestrial carbon is stored within the mantle and can be converted into atmospheric carbon via the process of ‘out-gassing’ by volcanoes, where they let out carbon dioxide during eruptions.
The role of organisms
The role of organisms
- Photosynthesis - plants remove carbon dioxide from the atmosphere to produce energy for plant growth.
- Respiration - all living organisms release carbon dioxide as they breathe and grow.
- Decomposition - when living organisms die, they are broken down, releasing carbon dioxide into the soil.
- Combustion - the burning of biomass or fossil fuels, both by man and in natural wildfires, releases carbon dioxide back into the atmosphere.
Oceans
Oceans
- Aquatic plants and animals (organic matter) fall to the ocean bed after death.
- Due to compression and cementation, they form into sedimentary rock.
- During these processes, crude oil and natural gas can form.
Atmosphere
Atmosphere
- Carbon dioxide is stored as a gas in the atmosphere.
- Carbon can leave the atmosphere when mixing with water vapour. When precipitation happens this falls as carbonic acid (commonly referred to as acid rain).
Fluxes varying in size
Fluxes varying in size
- The carbon cycle can happen at different scales and timeframes.
- The quickest cycle is completed in seconds during photosynthesis.
- But, it can take years for dead organic material to be returned.
- Some organic material will be buried in the sea and form into sedimentary rock, which is an extremely slow process.
Geological Carbon Stores
Geological Carbon Stores
In the formation of sedimentary rock, carbon can be found in several different forms including limestone, crude oil, coal and natural gas.
Formation of limestone
Formation of limestone
- Phytoplankton have carbon-based shells. Other marine organisms also have shells or skeletons that are formed from calcium carbonate.
- When these aquatic organisms die, they sink to the bottom of the ocean.
- As more sediment falls on top of them, they are compacted. When the sediment has reached around 100 metres in depth, the pressure and chemical reactions cause cementation to take place. This leads to the formation of limestone rock.
Formation of crude oil
Formation of crude oil
- Crude oil starts with the settling of fine-grained sediments and biologically degraded materials. There needs to be a minimum of 2% organic carbon.
- A series of anaerobic reactions (reactions happening without oxygen) happen to turn the majority of the organic carbon into a liquid (crude oil).
- Due to its light density, crude oil may migrate upwards through layers of permeable or porous rock. But a layer of impermeable rock will result in the crude oil being trapped.
Formation of coal
Formation of coal
- Coal is formed on land, unlike limestone and sedimentary rock which are formed in the oceans.
- When land-based plants die and enter into swamps, they slowly settle and compact to form peat and coal.
- Coal takes millions of years to form, depending on the temperatures and pressures.
Formation of natural gas
Formation of natural gas
- Methane (CH4) is an example of natural gas and is created as a by-product during the formation of coal and crude oil.
- Natural gas is trapped within the same sedimentary layers that coal and crude oil are found in.
1Tectonic Processes & Hazards
1.1Tectonic Processes & Hazards
1.2Natural Disasters
1.3Natural Disaster Case Studies
1.4Trends & Patterns
2Option 2A: Glaciated Landscapes & Change
2.1Glaciated Landscapes Over Time
2.2Periglacial Landscapes
2.3Glacial Processes
2.4Glacial Landforms
3Option 2B: Coastal Landscapes & Change
3.1Coastal Landscapes
3.2Coastal Erosion & Deposition
3.3Coastal Risks
4Globalisation
4.1Globalisation
4.2Negatives of Globalisation
4.3Global Shift
4.5Culture
4.6Measuring Development
5Option 4A: Regenerating Places
5.1Types of Economies
5.2Function of Places
5.3Regeneration
5.4Regeneration Case Studies
6Option 4B: Diverse Places
6.1Population Structure
6.2Past & Present Connections
6.3Urban & Rural Spaces
6.4Diversity
6.5Urban & Rural Case Studies
6.6Case Study - Tower Hamlets
6.7Case Study - Sturton-le-Steeple
7The Water Cycle & Water Insecurity (A2 only)
7.1Hydrological Processes Global to Local
7.2Influences on the Water Cycle
7.3Water Insecurity
8The Carbon Cycle & Energy Security (A2 only)
8.1The Carbon Cycle
8.2Energy Consumption
8.3Alternative Energy
8.4Growing Demand for Resources
9Superpowers (A2 only)
9.1Superpowers
9.2Hard & Soft Power
9.2.1Hard & Soft Power
9.2.2Emerging Powers - China Rivalry
9.2.3Emerging Powers - Chinese Sources of Power
9.2.4Emerging Powers - Brazil
9.2.5Emerging Powers - Russia
9.2.6Emerging Powers - India
9.2.7Theories of Development
9.2.8Power Case Studies: Chinese One Belt One Road
9.2.9Power Case Studies: Pakistan Nuclear Arms
9.2.10Power Case Studies: OPEC
9.3IGOs, TNCs & Alliances
10Option 8A: Health & Human Rights (A2 only)
10.1Human Development
10.2Role of Governments & IGOs
10.3Human Rights
10.4Interventions
11Option 8B: Migration & Identity (A2 only)
11.1Globalisation & Migration
11.2Consequences of Migration
11.3Nation States
11.4Responses to Global Migration
Jump to other topics
1Tectonic Processes & Hazards
1.1Tectonic Processes & Hazards
1.2Natural Disasters
1.3Natural Disaster Case Studies
1.4Trends & Patterns
2Option 2A: Glaciated Landscapes & Change
2.1Glaciated Landscapes Over Time
2.2Periglacial Landscapes
2.3Glacial Processes
2.4Glacial Landforms
3Option 2B: Coastal Landscapes & Change
3.1Coastal Landscapes
3.2Coastal Erosion & Deposition
3.3Coastal Risks
4Globalisation
4.1Globalisation
4.2Negatives of Globalisation
4.3Global Shift
4.5Culture
4.6Measuring Development
5Option 4A: Regenerating Places
5.1Types of Economies
5.2Function of Places
5.3Regeneration
5.4Regeneration Case Studies
6Option 4B: Diverse Places
6.1Population Structure
6.2Past & Present Connections
6.3Urban & Rural Spaces
6.4Diversity
6.5Urban & Rural Case Studies
6.6Case Study - Tower Hamlets
6.7Case Study - Sturton-le-Steeple
7The Water Cycle & Water Insecurity (A2 only)
7.1Hydrological Processes Global to Local
7.2Influences on the Water Cycle
7.3Water Insecurity
8The Carbon Cycle & Energy Security (A2 only)
8.1The Carbon Cycle
8.2Energy Consumption
8.3Alternative Energy
8.4Growing Demand for Resources
9Superpowers (A2 only)
9.1Superpowers
9.2Hard & Soft Power
9.2.1Hard & Soft Power
9.2.2Emerging Powers - China Rivalry
9.2.3Emerging Powers - Chinese Sources of Power
9.2.4Emerging Powers - Brazil
9.2.5Emerging Powers - Russia
9.2.6Emerging Powers - India
9.2.7Theories of Development
9.2.8Power Case Studies: Chinese One Belt One Road
9.2.9Power Case Studies: Pakistan Nuclear Arms
9.2.10Power Case Studies: OPEC
9.3IGOs, TNCs & Alliances
10Option 8A: Health & Human Rights (A2 only)
10.1Human Development
10.2Role of Governments & IGOs
10.3Human Rights
10.4Interventions
11Option 8B: Migration & Identity (A2 only)
11.1Globalisation & Migration
11.2Consequences of Migration
11.3Nation States
11.4Responses to Global Migration
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