The Carbon Cycle

Question 1

What are 5 of the most common carbon compounds? (It bonds easily with other molecules)

Answer 1

1. Carbon dioxide - a gas found i the atmosphere soils and oceans
2. Methane - a gas found in the atmosphere, soils and oceans and sedimentary rocks
3. Calcium carbonate - a solid compound found in calcareous rocks, oceans and in the skeletons and shells of ocean creatures
4. Hydrocarbons - soils, liquids or gases usually found in sedimentary rocks
5. Bio-molecules - complex carbon compounds produced in living things. Eg DNA, proteins, fats. Form 50% of the total sry mass of living things

Question 2

What is Anthropogenic CO2?

Answer 2

Carbon dioxide generated by human activity

Question 3

What is carbon sequestion?

Answer 3

The capture of carbon dioxide (CO2) from the atmosphere or capturing anthropogenic (human) CO2 from large scale stationary sources like power plants before it is released into the atmosphere. Once captured, the CO2 gas (or the carbon portion of the CO2) is put into long term storage.

Question 4

What is carbon sink?

Answer 4

A store of carbon that absorbs more carbon than it releases

Question 5

What is weathering?

Answer 5

The breakdown of rocks in situ by a combination of weather, plants and animals.

Question 6

What is the carbon cycle ?

Answer 6

1.Carbon is an essential building block for all life on earth.
2.It plays a major role on regulating global climate, particularly temperature and the acidity of rain, rivers and oceans.
3. The carbon cycles have inputs, stores, flows and outputs that transfer carbon from one place to another and either deplete or build carbon stores

Question 7

Describe and explain the varying size of global carbon flows?

Answer 7

1. Slow carbon cycle: the movement of carbon between the atmospheric, oceans and lithospheres
   - the atmosphere, oceans and land are linked together transferring carbon in a giant slow - moving system which takes between 100 and 200 million years for carbon to flow through it
2. Fast carbon cycle: the movement of carbon from living things to the atmosphere or oceans
   - the fast cycle through the biosphere moves up to a 1000x more carbon in a shorter space of time

Question 8

What are the processes changing the size of these stores?

Answer 8

Photosynthesis
Respiration
Combustion
Decomposition
Diffusion
Weathering ands erosion
Burial and compaction
Carbon sequestion

Question 9

Explain how photosynthesis changes the size of the carbon stores?

Answer 9

Living organisms convert carbon dioxide from the atmosphere and water from the soil, into oxygen and glucose using light energy. By removing co2 from the atmosphere, plants are sequestering okays carbon and reducing potential impacts of climate change. The process of photosynthesis occurs when chlorophyll in the leaves of the plant react with co2 to create the carbohydrate glucose. Photosynthesis helps to maintain the balance between oxygen and co2 in the atmosphere.

Carbon dioxide + water -> light energy -> oxygen + glucose

Question 10

Explain how respiration changes the size of the carbon stores?

Answer 10

Respiration occurs when plants and animals convert oxygen and glucose into energy which then produces waste products of water and co2. It is therefore chemically the opposite of photosynthesis.

Oxygen + glucose -> carbon dioxide + water

During the day, plants photosynthesise, absorbing significantly more co2 than they emit from respiration. During the night they do not photosynthesise but they do respire, releasing more co2 than they absorb. Overall, plants absorb more co2 than they emit, so are net carbon dioxide absorbers (from the atmosphere) and net oxygen producers (to the atmosphere).

Question 11

Explain how combustion changes the size of the carbon stores?

Answer 11

When fossil fuels and organic matter such as trees are burnt, they emit CO2 into the atmosphere, that was previously locked inside of them. This may occur when fossil fuels are burnt to produce energy, or if wildfires occur

Question 12

Explain how diffusion changes the size of the carbon stores?

Answer 12

The oceans can absorb co2 fro the atmosphere, which has increased ocean acidity by 30% since pre-industrialised times. The ocean is the biggest carbon store, but with carbon levels increasing seawater becomes ore acidic which is harming aquatic life by causing coral bleaching. Many of the world’s coral reefs now are under threat

Question 13

Explain how weathering and erosion changes the size of the carbon store?

Answer 13

Rocks are eroded on land or broken down by carbonation weathering. Carbonation weathering occurs when co2 in the air mixes with rainwater to create carbonic acid which aids erosion of rocks such as limestone. The carbon is moved through the water cycle and enters the oceans. Marine organisms use the carbon in the water to build their shells. Increasing carbon dioxide levels in the atmosphere, may increase weathering and erosion as a result, potentially affecting other parts of the carbon cycle.

Question 14

Explain how burial and compaction changes the size of the carbon store?

Answer 14

When shelled marine organisms due, their shell fragments fall to the ocean floor and become compacted over time to form limestone. Organic matter from vegetation and decaying marine organisms is compacted over time, whether on land or in the sea, to form fossil fuel deposits.

Question 15

Explain how carbon sequestration changes the size of the carbon store?

Answer 15

Transfer of carbon from the atmosphere to other stores and can be both natural and artificial. A plant sequesters carbon when it photosynthesises snd stores the carbon in its mass. Factories are also starting to use carbon sequestration in the for of Carbon Capture and Storage. CO2 is captured and transported via pipelines to depleted gas fields and saline aquifers.

Question 16

What are the advantages of carbon sequestration?

Answer 16

• can be fitted to existed coal power station
• capture 90% of co2 produced
• there is a demand for co2 (beer, cola), so transport systems via pipeline in liquid form already exist
• potential to capture half the worlds co2 emissions

Question 17

What are the disadvantages of carbon sequestration (CCS)?

Answer 17

• high cost is the main restriction to the growth of CCS
• increased energy demand for power stations
• may not be space to fit to existing power stations
• economically viable in some cases as it is used to push oil out the ground, thus increasing fossil fuel usage

Question 18

Describe and explain the varying size of global carbon stores?

Answer 18

The lithosphere (biggest store, however unevenly distributed, north south hemisphere) has the largest magnitude, with a total percentage of carbon around 99.9%. The carbon comes in the forms sedimentary rocks, organic carbon, fossil fuels, marine sediments.
- 400 billion metric tons of carbon remain as fossil fuels
- 1500 billion metric tons of carbon stored in organic matter

The hydrosphere has the second largest magnitude, around 0.007% of the total carbon %. It comes in the form of carbonate ions, bicarbonate ions and dissolved co2.
- 38,000 billion metric tons of carbon

The cryosphere has a smaller magnitude of 0.0018% of total carbon. It is in the form of frozen mosses

Smaller is the atmosphere, with 0.0015%. Carbon stored in the form of gaseous carbon.
- makes us 0.04% of the atmosphere

The smallest is the biosphere, with a magnitude f 0.0012 %. Stored in the form of living plants and animals.
- 19% of this store is in plants

Question 19

How does Wildfires effect the carbon cycle over time?

Answer 19

Natural Variation
- combustion of biomass and fossil fuels
Combustion occurs when any organic material is related in the presence of oxygen to give off the produces of c02, h20 and energy. This organic material can be vegetation or fossil fuel such as natural gas, oil or coal. Trees die after sever fires, setting the stage for new growth, therefore no net carbon change. The fires only consume 10-20% of the carbs and it is emitted immediately into the atmosphere. It kills trees but does bot consume them. So new trees grow (storing carbon), old trees decompose (emitting carbon) and the organic layer of the soil accumulates (storing carbon). This balance between simultaneous production and decomposition determines whether the forest is a net source or sink. Left alone, terrestrial and atmospheric conditions stay more or less in balance.

Question 20

How does volcanic activity effect the carbon cycle over time?

Answer 20

Natural Variation
The warming effect of emitted co2 is counterbalanced by the large amounts of sulphur dioxide that is give out-conversions of thus it sulphuric acid, which forms fine droplets, increases the reflection of radiation from the sun back into space, following the earths lower atmosphere. The amounts of co2 released have not been enough to produce detectable global warming.
- in 1815 MT Tambrora eruption in Indonesia produces sulphur dioxide gas, which blocked radiation from the sun and lowered global temperatures by 0.4 to 0.7 degrees in 1816.

However in this way volcanoes can influence the carbon cycle by reducing photosynthesis rates, which in turns affects the water cycle.

Question 21

How does hydrocarbon fuel extraction and burning affect the carbon cycle over time?

Answer 21

HUMAN
Cement manufacture contributes co2 to the atmosphere when calcium carbonate is heated producing lime and co2. Co2 is also produced by the burning of fossil fuels that provide heat for the cement manufacture process

Question 22

How do farming practises affect the carbon cycle over time?

Answer 22

HUMAN
Arable farming releases co2 as animals respire. Ploughing can release co2 stored in the soil into the atmosphere. In addition to the effects on the soil from ploughing, emissions from the tractors increase carbon dioxide levels in the atmosphere.

Question 23

How does deforestation affect the carbon cycle over time?

Answer 23

HUMAN
Most deforestation is driven by the need for extra agricultural land. When forests are cleared for conversion to agriculture or pasture, a large proportion of the above ground biomass may be burned, rapidly releasing most of its carbon into the atmosphere. Some of the wood may be used for wood products and so preserved for a longer period of time. Forests clearing also accelerates the decay of dead wood,litter and below ground organic carbon
- according to global forest watch that since 2001 to 2018, the tree cover lost globally is 1.5x the size of the UK. This has released an estimated 98.7 Gtc of Co2 emissions.

Question 24

How does land use change (urban growth) affect the carbon cycle over time?

Answer 24

As cities grow, the land use changes from agricultural or natural to built environment. The co2 emissions resulting from energy consumption for transport, industry and domestic use and cement production have been required to built the increase in infrastructure.
- urban areas estimated to be responsible for 75% of global carbon emissions

Question 25

Describe and explain the changes in the global carbon cycle over time (temporal changes)?

Answer 25

DAY / NIGHT
1. During the night photosynthesis stops and respiration is the dominant process s co2 concentrations are high
2. As the sun comes up, photosynthesis begins to take up atmospheric co2 and the levels begin to drop
3. By midday, the sun is high in the sky and photosynthesis is now the dominant process so co2 levels in the atmosphere are at their lowest
4. As the sun starts to go down, photosynthesis decreases and co2 increases as a result.

SEASONS
1. During the winter and early spring, respiration is the dominant process as although photosynthesis is operating, there is very limited or no plant growth
2. Peak co2 coincides with the springtime and the beginning of the growing seasons where photysnthesis takes over as the dominant process
3. Co2 in the atmosphere decreases during the growing season as photosynthesis dominates, removing co2 and locking it up in plants and trees
4. Low co2 coincides with the late summer and the end of the growing seasons when trees have stopped locking up co2.
5. The animus peak of atmospheric co2 is April and May after the winter months when there is very little growing happening. Respiration, by which plants and animals take up oxygen and releases c02, occurs all the time but dominates in the colder months.

Question 26

Describe and explain the carbon cycle at sere and plant scales?

Answer 26

PLANT SCLAE
If the carbon input from photosynthesis is greater than the carbon output from respiration, trees will biosynthesise more and biomass resulting in greater carbon storage. Measures of NPP (net primary production) will be higher. Conversely, if the output of respiration is greater than the carbon input of photosynthesis, less carbon will be stored and measures of NPP will be lower. This is an open kind of system.

SERE SCALE
The carbon cycle occurs on a local scale in a sere. A sere is a stage of vegetation succession and can relate to specific environments. A vegetation succession occurs when a plant community develops and becomes more complex over time. The climatic climax is the final stage of the sere where environmental equilibrium is achieved. In the most of the UK this would be a woodland. When a sere reaches a climatic climax, the ecosystem is fully developed and stable, and it will not change dramatically as the equilibrium will counteract any change (unless there is a major climatic or geographical change).
Eg, Pine Bark Beetle infestations have been part of the natural ecology of western forests for a long time. However the severity and frequency have been increasing rapidly.

Question 27

How does decomposition change the magnitude of carbon stores over time?

Answer 27

When living organisms die, they are broken down by decomposes (such as bacteria), which respire, returning co2 into the atmosphere. Some organic matter is also returned to the soil where it is stored adding carbon matter to the soil

Question 28

What is the carbon budget?

Answer 28

The balance of the exchange between the 4 major stores of carbon

Question 29

What is sequestration?

Answer 29

Capture and long term storage of the atmospheric carbon

Question 30

Which stores would you associate with long term storage? Why?

Answer 30

Atmosphere
Hydrosphere
Biosphere

Photosynthesis and respiration (atmosphere and biosphere)
Ocean atmosphere gas exchange (atmosphere and hydrosphere)

Question 31

Which stores would you associate with long term storage? Why?

Answer 31

Lithosphere - calcium sediment in the deep ocean turned to limestone
Hydrosphere (deep ocean) - calcium carbonate

Question 32

What is the main impact of the changing carbon budget on the land? How significant is this impact?

Answer 32

Thaws Permafrost
1672 Gtc of carbon in permafrost. If 10% were to thaw then global atmospheric temps could rise by 0.7C.

Question 33

What is ocean acidification? How significant is this impact?

Answer 33

(Increases capacity to absorb more carbon)
When carbon dissolves in carbonic acid, raises oceans acidity. This makes the ocean slightly less alkaline. This makes animals shells weaker + thinner and can lead to significant reef loss which provides food and livelihood for over 600 million people
Since the 1750s there has been a 30% acidity change in the acidity of oceans.

Question 34

What is ocean warming? How significant is this impact?

Answer 34

Ice melts, replaced by oceans, ocean absorbs more sunlight, in turn ocean warms more, more melting (Positive feedback)
- limits oceans ability to take carbon from the atmosphere
- kills reeds (high ocean temps)

Question 35

What is the main impact of the changing carbon budget on the cryosphere? How significant is this impact?

Answer 35

Melting sea ice - 40% loss of Artic sea ice in the last 3 years. When sea ice melts which is highly reflective it is replaced with more heat absorb ant water. Oceans absorb more sunlight, which can amplify sea ice melt.
This can lead to further ocean warming and sea level rise.
Melting sea ice can also lead to increase of freshwater in the ocean, which can affect ocean salinity.

Question 36

What is ocean salinity? How significant is this impact ?

Answer 36

How much salt is in the water
Higher temperatures, melting ice sheets, increase in freshwater in oceans, slowing down oceanic circulation in the north east Atlantic , which can affect the climate of north wester Europe.

Question 37

What is sea level rise? How significant is this impact?

Answer 37

Melting of terrestrial ice (increase in freshwater entering the ocean)
Thermal expansion (warmer oceans have greater volume)
Predicted sea level rise ranges from 0.8m to 2m by 2100.

Question 38

What is the main impact of the changing carbon budget on the atmosphere? How significant is this impact?

Answer 38

Enhanced greenhouse effect - this can lead to positive feedback mechanisms that can enhance ocean warming, ice sheets melting, permafrost melting and ocean acidification (can have global scale effects)

Greenhouse gases - can cause radiative forcing. Can cause an Increase of 1.5 degrees between 2030 and 2050

Radiative forcing - the difference between incoming solar energy absorbed by the earth and energy radiated back to space.