W&C - The Carbon Cycle: Global Scale Flashcards
What is a carbon sink?
A store that takes in more carbon than it emitts
What is a carbon source?
A store that emits more carbon than it stores
Name the main global stores of carbon
- marine sediment and sedimentary rock
- oceans
- fossil fuel deposits
- soil organic matter
- atmosphere
- terrestrial plants
What natural processes affect the global carbon stores over time?
- 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
What human processes affect the global carbon stores over time?
- 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
Describe the enhanced greenhouse effect
- 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
What are the causes of the human enhanced greenhouse effect?
- deforestation
- urbanisation
- farming practices
Describe the Milankovitch cycle and its link to the carbon cycle?
- 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
What is the impact of the carbon cycle on tropical rainforests?
- 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
What is the impact of the carbon cycle on oceans?
- 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)
Give an example of positive feedback in the carbon cycle
- increasing global temperatures
- warmer oceans absorb less CO2
- more CO2 in the atmosphere leads to the enhanced greenhouse effect, which increases temperatures more
What is the relationship between the two cycles?
- 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
give an example of negative feedback in the carbon cycle?
- rising global temperatures allows vegetation to grow in new areas
- new vegetation photosynthesises and absorbs CO2
- reduces CO2 levels in the atmosphere
- decreases the warming effect