Carbon Cycle Pack A Flashcards
What characteristics do systems have?
- Inputs
- Outputs
- Stores
- Processes
- Equilibrium
- Feedback
- Tipping points
What are the stores in the carbon cycle?
- Lithosphere and sedimentary rocks 99.9% (fossil fuels = 0.007%) with a residence time of 150 million years
- Oceans 0.064% with a residence time of 25-1000 years
- Biosphere 0.03% with a residence time of 18 years
- Atmosphere 0.01% with a residence time of 6 years
How do feedback cycles happen in the carbon cycle?
- Negative feedback maintain a stable state by preventing the system moving beyond thresholds (cancelling change)
e.g. Rising temperatures and photosynthesis - Positive feedbacks shifts the system away from its previous state to a new one
e.g. Permafrost
What are the three main ways humans are adding carbon to the atmosphere?
- Burning fossil fuels
- Making cement
- Deforestation
What is the photosynthesis flow of carbon between vegetation and the atmosphere?
- Terrestrial and marine vegetation photosynthesises
- Energy from the sun is used to turn CO2 into carbohydrates
- Form of carbon sequestration
What is the respiration flow of carbon between vegetation and the atmosphere?
- Oxygen is combined with carbohydrates to release energy
- CO2 and water is released
- Happens at day and night
What is the decomposition flow of carbon between vegetation and the atmosphere?
- Decomposers break down cells and tissues in dead organisms
- Fungi, worm and bacteria respire and release CO2
- Some plants become part of the sedimentary rock and fossil fuel pools if not decomposed
- Some plants become peat due to slow decomposition
What is the biomass combustion flow of carbon between vegetation and the atmosphere?
- Burning of vegetation
- Natural fires takes stores of carbon from vegetation and releases it to the atmosphere
- Vegetation cannot become humus and litter, impacting soil
E.g. Australia wildfires
How much carbon dioxide is in the atmosphere?
Before the Industrial Revolution = 280PPM
Now = 423PPM
% of atmosphere = 0.04%
What is adding more carbon to the atmosphere?
Fossil fuel combustion:
- Process of burning coal, oil, natural gases, or other fossil fuels for energy
- Creates 80% of the world’s energy
- Stored carbon is released
Cement industry:
- Creates 5% of worldwide man-made emissions
- 50% of which is from the chemical process
- 40% of which is from burning fuel
Clearing/burning tropical forests:
- Accounts for 20% of global annual greenhouse gas emissions
How does carbon move into water?
- Rivers take ions to the sea, where they settle as CaCO3
- Water dissolves CO2 (warm water = less CO2 dissolved)
- Total store of the oceans is 40000GtC
How does the biological ocean pump work?
- Carbon from the atmosphere is incorporated into marine organisms as shells
- Carbon is released into the water when organisms die and decay
- Shells can also become part of the sedimentary rock
How does the physical ocean pump work?
- Vertical deep mixing
- Warm waters are carried from the tropics to polar regions
- Water cools, so it becomes denser and sinks taking the CO2 with it
- Water rises in the tropics and cold water from the poles is drawn in
- As it rises it takes CO2 to the surface, warms up and releases CO2
What is the absorption by biota flow of carbon between the atmosphere and ocean
- Phytoplankton absorb Co2 by photosynthesis
- Passes through the marine food chain when phytoplankton are eaten
- Sea shell organisms contain carbonate
- When dead organisms settle on seabed some carbon ends up in sediments
- CO2 is absorbed by the water and cold water holds more
What is the slow carbon cycle?
- The geological component of the carbon cycle
- Processes of weathering, burial, subduction and volcanisms control carbon concentrations over long periods of time
How does the slow carbon cycle work? Weathering
- CO2 is lost when it dissolves in rainwater
- Falls as carbonic acid
- It reacts with minerals in rocks to slowly dissolve them (carbonation)
- Dissolves calcium carbonate in rocks, changing minerals containing lime into soluble bicarbonates
- These are carried by water into oceans, where animals use it to make shells
How does the slow carbon cycle work? River transport
- River transport, throughflow and groundwater flow take dissolved calcium carbonate to the oceans
- Rivers also carry stones, sediment and biomass
How does the slow carbon cycle work? Sequestration over millions of years?
- Coral and other marine organisms use CaCO3 for their skeletons and shells
- When they die, remains get overlaid by sediment and turn into limestone (a sedimentary rock)
How does the slow carbon cycle work? Tectonic uplift
- Exposes the buried rock (e.g. Himalayas) and it is weathered
- When seafloor is lost at a destructive boundary, the carbonaceous seafloor depsits are pushed deep into the mantke
- They heat up, melt and rise as magma in volcanic eruptions
- CO2 is lost to the atmosphere in eruptions
How does the slow carbon cycle work? Volcanic activity
- Gases and carbon is ejected material enter the atmosphere or move to the land
