W&C - The Carbon Cycle: Global Scale

Question 1

What is a carbon sink?

Answer 1

A store that takes in more carbon than it emitts

Question 2

What is a carbon source?

Answer 2

A store that emits more carbon than it stores

Question 3

Name the main global stores of carbon in order of magnitude

Answer 3

• marine sediment and sedimentary rock
• oceans
• fossil fuel deposits
• soil organic matter
• atmosphere
• terrestrial plants

Question 4

What natural processes affect the global carbon stores over time?

Answer 4

• volcanic activity = carbon stored in the lithosphere is released into the atmosphere during volcanic eruptions
• wildfire = release large amounts of CO2 into the atmosphere that plants were previously storing (biosphere) + global warming is providing better conditions for wildfires to occur

Question 5

What human processes affect the global carbon stores over time?

Answer 5

• farming practices - pastoral farming released CO2 through animal respiration
• deforestation - slash and burn techniques to clear land for settlements releases CO2 from the biosphere to the atmosphere
• fossil fuel use (combustion) = transfers CO2 from a long term sink to the atmosphere

Question 6

Describe the enhanced greenhouse effect

Answer 6

• greenhouse gases create an ozone layer that traps solar radiation and in turn increases global temperatures
• human activities release more greenhouse gases into the atmosphere, which thickens this layer, leading it to trap even more solar radiation, and further warm the planet

Question 7

What are the causes of the human enhanced greenhouse effect?

Answer 7

• deforestation
• urbanisation
• farming practices

Question 8

Describe the Milankovitch cycle and its link to the carbon cycle?

Answer 8

• the earths orbital variations means that there are periods of time where we experience greater heating from the sun
• opposite can happen, which leads to glacial periods (ice ages)
• increasing global temperatures
• causes glaciers to melt, which releases cryospheric CO2 in the atmosphere
• these orbital variations initiate the process, but the increase in CO2 levels in the atmosphere emphasise it

Question 9

What is the impact of the carbon cycle on tropical rainforests?

Answer 9

• deforestation decreases photosynthesis, which increase the amount of CO2 in the atmosphere
• also reduces interception, which can lead to soil erosion, transferring CO2 stored in the soil into rivers

Question 10

What is the impact of the carbon cycle on oceans?

Answer 10

• increasing global temperatures
• warmer oceans absorb less CO2
• more CO2 in the atmosphere leads to the enhanced greenhouse effect, which increases temperatures more
  (Positive feedback)

Question 11

Give an example of positive feedback in the carbon cycle

Answer 11

• increasing temperatures
• increased vegetation growth
• more photosynthesis
• less CO2 in the atmosphere
• reduces the warming effect

Question 12

What is the relationship between the two cycles?

Answer 12

• deforestation reduces photosynthesis, so less CO2 intake
• also less interception and an increase in infiltration
• precipitation over deforested land means there is a lack of interception, which can lead to soil erosion, and the CO2 in the soil can be transferred into rivers