The Carbon Cycle

Question 1

How much carbon is stored in the lithosphere?

Answer 1

Over 99.9% of the carbon on Earth is stored in sedimentary rocks such as limestone.

Question 2

How much carbon is stored in fossil fuels?

Answer 2

About 0.004% of the carbon on Earth is stored in fossil fuels, such as coal and oil, in the lithosphere.

Question 3

How much carbon is stored in the atmosphere?

Answer 3

Carbon is stored as carbon dioxide and in smaller quantities as methane in the atmosphere. The atmosphere contains about 0.001% of the Earth’s carbon.

Question 4

How much carbon is stored in the biosphere?

Answer 4

Carbon is sored in the tissues of living organisms. It is transferred to the soil when living organisms die and decay. The biosphere contains approximately 0.004% of the Earth’s total carbon.

Question 5

How much carbon is stored in the cryosphere?

Answer 5

The cryosphere contains less than 0.01% of Earth’s carbon. Most of the carbon in the cryosphere is in the soil in areas of permafrost (permanently frozen ground) where decomposing plants and animals have frozen into the ground.

Question 6

How much carbon is stored in the hydrosphere?

Answer 6

Carbon dioxide is dissolved in rivers, lakes and oceans. The oceans are the second largest carbon store on Earth, containing approximately 0.04% of the Earths carbon. The majority of carbon here is found deep in the ocean in the form of dissolved inorganic carbon. A small amount is found at the ocean surface where it is exchanged with the atmosphere.

Question 7

What is the carbon cycle?

Answer 7

The carbon cycle is the process by which carbon is stored and transferred.

Question 8

Why is the carbon cycle a closed system?

Answer 8

There are inputs and outputs of energy, but the amount of carbon in the system remains the same. However, some carbon is locked away in long term stores, rock and fossil fuels deep underground.

Question 9

Name 7 stores in the carbon cycle?

Answer 9

Atmosphere, vegetation, soils, fossil fuels, earth’s crust, oceans and sediments.

Question 10

Name 5 outputs in the carbon cycle?

Answer 10

Volcanic eruptions, burning fossil fuels, combustion, respiration and ocean loss.

Question 11

Name 5 inputs in the carbon cycle?

Answer 11

Photosynthesis, Sequestration, Decomposition, Chemical rock weathering and sequestration and Ocean Uptake.

Question 12

Why do carbon stores change in size over time?

Answer 12

Because of carbon flows.

Question 13

What does photosynthesis transfer?

Answer 13

It transfers carbon stored in the atmosphere to biomass.

Question 14

What do plants and phytoplankton do?

Answer 14

Plants and phytoplankton use energy from the Sun to change carbon dioxide and water into glucose and oxygen. This enables plants to grow.

Question 15

How is carbon released if it passes through the food chain?

Answer 15

It is released through respiration and decomposition.

Question 16

What does combustion transfer carbon to?

Answer 16

Combustion transfers carbon stored in living, dead or decomposed biomass to the atmosphere by burning.

Question 17

What do wildfires cause?

Answer 17

They cause carbon flow.

Question 18

What does respiration transfer?

Answer 18

Respiration transfers carbon from living organisms to the atmosphere.

Question 19

What do plants and animals break down?

Answer 19

They break down glucose for energy, releasing carbon dioxide and methane in the process.

Question 20

What does decomposition transfer carbon to?

Answer 20

Decomposition transfers carbon from dead biomass to the atmosphere and the soil.

Question 21

What is released during decomposition?

Answer 21

After death, bacteria and fungi break organisms down. Carbon dioxide and methane are released.

Question 22

What is carbon dioxide dissolved into?

Answer 22

Carbon dioxide is directly dissolved from the atmosphere into the ocean.

Question 23

Where is the carbon also transferred to?

Answer 23

It is also transferred from the ocean to the atmosphere when carbon rich water from deep in the oceans rises to the surface and releases carbon dioxide.

Question 24

What does weathering transfer carbon?

Answer 24

Chemical weathering transfers carbon from the atmosphere to the hydrosphere and biosphere.

Question 25

What does atmosphere carbon react with and what happens because of this?

Answer 25

Atmosphere carbon reacts with water vapour to form acid rain. When this acid rain falls onto rocks, a chemical reaction occurs which dissolves the rocks.

Question 26

What happens to the molecules from the chemical reaction involving the acid rain and rocks?

Answer 26

The molecules resulting from this reaction may be washed into the sea. Here, they react with carbon dioxide dissolved in the water to form calcium carbonate, which is used by sea creatures, to make shells.

Question 27

What does sequestrated mean?

Answer 27

Carbon from the atmosphere can be captured and held in sedimentary rocks or as fossil fuels.

Question 28

What does fast carbon flow refer to?

Answer 28

Fast carbon flows quickly transfer carbon between sources. It only takes a matter of minutes, hours or days.

Question 29

Name 4 examples of fast carbon flows?

Answer 29

Photosynthesis, respiration, combustion and decomposition.

Question 30

Name an example of a slow carbon flow?

Answer 30

Sequestration is a slow carbon flow. It take millions of years for carbon to be sequestrated in sedimentary rocks.

Question 31

Name two natural events that can alter the magnitude of the carbon stores?

Answer 31

Wildfires and Volcanic Activity.

Question 32

How can wildfires alter the magnitude of carbon stores?

Answer 32

Wildfires rapidly transfer large quantities of carbon from biomass to the atmosphere. Loss of vegetation decreases photosynthesis, so less carbon is removed from the atmosphere.

Question 33

How can wildfires in the long term affect the carbon cycle?

Answer 33

In the longer term, however fires can encourage the growth of new plants, which take in carbon from the atmosphere for photosynthesis.

Question 34

Can wildfires have a neutral effect on the amount of atmospheric carbon?

Answer 34

Yes, depending on the amount and type of regrowth, fires can have a neutral effect on the amount of atmospheric carbon.

Question 35

How can volcanic activity alter the magnitude of the carbon stores?

Answer 35

Carbon stored within the Earth in magmas is released during volcanic eruptions. The majority enters the atmosphere as carbon dioxide.

Question 36

How does hydrocarbon extraction and use impact the carbon cycle?

Answer 36

Extracting and burning of fossil fuels releases carbon dioxide into the atmosphere. Without human intervention, the carbon would remain sequestrated in the lithosphere for thousands or millions of years to come.

Question 37

How does deforestation impact the carbon cycle?

Answer 37

Forests may be cleared for agriculture, logging, or to make way for developments. Clearance reduces the size of the carbon store and, if the cleared forest is burned, there is a rapid flow of carbon from the biosphere to the atmosphere.

Question 38

How does land use changes impact the carbon cycle?

Answer 38

The change of land use from natural or agricultural to urban is a major source of carbon. Vegetation is removed to make way for buildings - this reduces carbon storage in the biosphere.

Question 39

How does concrete production impact the carbon cycle?

Answer 39

It releases lots of carbon dioxide and lots of concrete is used when urban areas expand.

Question 40

How does farming practises impact the carbon cycle?

Answer 40

Agricultural activities release carbon into the atmosphere:
Animals release carbon dioxide and methane when they respire and digest food.
Ploughing can release carbon dioxide stored in the soil.
Growing rice in rice paddies releases a lot of methane.

Question 41

What has happened to farming practises recently?

Answer 41

As the worlds population has risen, so has food production. As a result, carbon emissions from farming practises have increased. Mechanisation of farming has also increased carbon dioxide emissions.

Question 42

What is the carbon budget?

Answer 42

The carbon budget is the difference between the inputs of carbon into a subsystem and outputs of carbon from it.

Question 43

What is an example of the a carbon budget?

Answer 43

In the atmosphere inputs of carbon come from volcanic eruptions, burning fossil fuels, respiration and ocean loss, and outputs occur through photosynthesis, sequestration, decomposition, chemical weathering and ocean uptake.

Question 44

What is a carbon source?

Answer 44

The outputs of carbon outweigh the inputs, so it releases more carbon than it absorbs.

Question 45

What is a carbon sink?

Answer 45

The inputs of carbon outweigh the outputs, so it absorbs more carbon than it releases.