Lesson 8-What are the factors driving change in the carbon cycle? Flashcards
1
Q
Fast and slow carbon cycles broken down even further
A
- Fast organic carbon cycles
- Fast nonorganic carbon cycles
-Slow organic carbon cycles
-Slow nonorganic carbon cycles
2
Q
Types of slow and fast carbon cycles- Fast organic carbon cycles
A
- The transfer of carbon by plants and animals from the atmosphere (air) to the biosphere (plants) and to the pedosphere (soil).
- Occurs quite quickly and is processes such as photosynthesis, respiration and decomposition.
3
Q
Types of slow and fast carbon cycles- Fast nonorganic carbon cycles
A
- This is the transfer of carbon from the atmosphere to the oceans and the other way round.
- This occurs quickly and is the process of diffusion.
4
Q
Types of slow and fast carbon cycles- Slow organic carbon cycles
A
- This is the transfer of carbon through the carbonate pump / solubility cycle from marine creatures to sedimentary rocks like limestone and coal.
- Takes hundreds or millions of years and involves the long term sequestration (storage
5
Q
Types of slow and fast carbon cycles-Slow nonorganic carbon cycles
A
- This is the transfer of carbon from the lithosphere back to the atmosphere through natural tectonic processes (volcanoes).
- This is very slowly and happens through subduction then volcanoes releasing CO2 when they erupt.
6
Q
The main carbon fluxes in the carbon cycle
A
- Photosynthesis
- Respiration
- Decomposition
- Fossil fuel combustion
- Land use change
- Carbon sequestration (in oceans and sediments)
- Weathering
7
Q
What are all the transfers of carbon?
A
- Weathering
- Burial and Compaction
- Carbon sequestration
- Combustion
- Decomposition
- Respiration
- Photosynthesis
8
Q
Transfers of carbon- Weathering
A
- Transfers carbon from the lithosphere
into the hydrosphere then the atmosphere - The main process is a form of chemical weathering calledcarbonation
- The atmosphere has CO2 that combines with water vapour to produce a weak acid known as carbonic acid, this makes precipitation slightly acidic
- When the acidic rain reacts with calcium carbonate in rocks it forms calcium bicarbonate
- This form of carbon is then dissolved in water and washed away via streams, rivers and oceans and eventually back into the atmosphere
9
Q
Transfers of carbon- Burial and Compaction
A
- Transfers carbon from the hydrosphere to the lithosphere
- Oceans also absorb carbon from the atmosphere via diffusion
- The carbon in the hydrosphere is converted into the shells and skeletons of marine creatures as calcium carbonate
- When the creatures die, they sink to the bottom and build up layers transferring carbon into the deep ocean store
- Over time they compact down (diagenesis) to create sedimentary rocks such as limestone in the lithosphere.
- Under heat and pressure (metamorphism), carbon from organic matter is trapped in the sediment and is converted into hydrocarbons – coal is formed.
10
Q
Transfers of carbon- Carbon sequestration
A
- Transfer of carbon from the atmosphere to the lithosphere or biosphere
- Natural sequestrationis the process where carbon is removed from the atmosphere and stored in the liquid or solid form e.g. rocks of the lithosphere, plants of the biosphere etc.
- This can be planting trees to naturally transfer carbon from the atmosphere to the biosphere.
- This can also be the formation of sedimentary rocks and hydrocarbons (see previous slide) to transfer carbon from the hydrosphere to the lithosphere.
11
Q
Transfers of carbon- Combustion
A
Transfer of carbon from the lithosphere or biosphere to the atmosphere
- This can come in a series of different forms and can be either natural or caused by humans.
- Tectonic activityover thousands of years moves the sea floor towards destructive plate boundaries, where they are subducted into the mantle.
-The extreme heat and pressure release the carbon in the rock back up to the surface where it returns to the atmosphere through volcanic eruptions by which 200 million tonnes are released per year
- Burningorganic material, this can be trees or burning fossil fuels, releases energy, water and CO2, industrial processes return carbon to the atmosphere that would otherwise have remained stored in rocks for millions of years
- Wildfiresrelease stored carbon in vegetation back into the atmosphere – climate change increases the risk of this.
12
Q
Transfers of carbon- Decomposition
A
- The transfer of carbon from the biosphere to the pedosphere (soil) and the atmosphere (air)
- When plants and animals die, they decompose through animals (worms), bacteria and fungi (collectively called decomposers) breaking down the carbohydrates
- This releases CO2 and methane back into the atmosphere, with some of the carbon being transferred into the soil in the form of humus
- Decomposition is temperature dependent, with warmer temperatures showing greater microbial activity and faster decomposition
- This means decomposition has a spatial pattern globally but also a seasonal pattern due to its link with temperature!
13
Q
Transfers of carbon- Respiration
A
- the transfer of carbon from the biosphere to the atmosphere
- Plants, and the animals that feed on them, break down carbohydrates to release the energy that they need to grow and survive
- As they do this, they release CO2, as a by-product, through respiration and waste gases, as they digest their food
- Life on Earth is fuelled by the breakdown of these carbohydrates which releases CO2 back into the atmosphere
14
Q
Transfers of carbon- Photosynthesis
A
- The transfer of carbon from the atmosphere into the biosphere
- Plants are primary producing organisms (they make their own food), as they use CO2 from the atmosphere and water in the soil using energy from sunlight to produce carbohydrates
- Plants cause natural carbon sequestration as they ‘fix’ carbon dioxide into solid form in their living tissues as glucose by taking it out of the atmosphere
- Oxygen is released as a bi-product back into the atmosphere
- In the oceans, microscopic organisms - phytoplankton - also do the same photosynthesising – this can transfer carbon from the atmosphere into the hydrosphere
15
Q
Where does the carbon go when we burn fossil fuels?
A
- It is a common misconception that all of it goes into the atmosphere.
About 40% goes into the atmosphere
- The rest is either absorbed by the oceans (diffusion) which can then be transferred into marine organisms and through thermohaline circulation and the biological pump eventually transferred back into the lithosphere
- Or it is stored on the land in soil or vegetation as plants are a natural sequester of carbon through photosynthesis.
16
Q
What are carbon sinks and why are they important?
A
- Now carbon sinks main function is to offset climate change by absorbing carbon that would otherwise all end up in the atmosphere.
- The carbon sinks have managed to increase there contribution by absorbing more carbon.
- This means concentrations in the atmosphere are much lower than they would be! This is why soil and our oceans are so important!
17
Q
What is the importance of the hydrosphere and the pedosphere?
A
- Without land and ocean sinks working overtime concentrations of carbon dioxide would be well beyond the 400 ppm recently observed in Hawaii.
- The ocean sink (-76 ppm) and land sink (-68 ppm) have absorbed 56% of human carbon emissions since 1750, keeping global carbon dioxide concentrations ‘down’ to 393 ppm in 2012.
- These natural sinks for carbon dioxide have been crucially important in slowing the growth of atmospheric carbon dioxide in the past.
- This is the importance of natural carbon sequenstration.
- However these stores can only absorb so much and when they are full any remaining carbon will go into the atmosphere.
- Furthermore through deforestation and soil degradation we are reducing the biosphere store.
