AQA · A-Level · Geography
Course version: 7037 · Version from Sept 2018
Factors driving change in the magnitude of these stores over time and…
Full specification wording
The carbon cycle: Factors driving change in the magnitude of these stores over time and space, including flows and transfers at plant, sere and continental scales. Photosynthesis, respiration, decomposition, combustion, carbon sequestration in oceans and sediments, weathering.
Carbon store magnitudes change over time and space through dynamic flows operating across multiple scales.
Checked against the AQA 7037 specification (opens in a new tab) on .
- Point 2 of 4
- 2 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Carbon store magnitudes change over time and space through dynamic flows operating across multiple scales. At the plant scale, photosynthesis removes atmospheric carbon, while respiration returns it. At the sere scale, ecosystems transition over time, altering carbon storage through decomposition and biomass accumulation. At the continental scale, weathering of silicate rocks and combustion of vast forests or fossil fuels drive massive carbon transfers. Carbon sequestration in oceans involves the physical and biological pumps transferring carbon to deep waters, while sedimentary sequestration locks carbon in the lithosphere for millions of years. These interconnected processes continuously alter the balance of global carbon reservoirs.
What earns the marks
- Explain how photosynthesis and respiration act as opposing flows at the plant scale, regulating local atmospheric carbon.
- Describe how decomposition breaks down organic matter, transferring carbon from the biosphere to the pedosphere and atmosphere at the sere scale.
- Analyse the role of combustion, both natural and human-induced, in rapidly transferring carbon from the biosphere and lithosphere to the atmosphere.
- Detail the process of carbon sequestration in oceans, including the biological pump and physical downwelling.
- Explain how chemical weathering of rocks transfers carbon from the atmosphere to the hydrosphere and eventually to ocean sediments.
Common mistakes and how to put them right
Confusing plant respiration with photosynthesis.
Put it right: Respiration releases carbon dioxide while photosynthesis absorbs it.
Treating weathering as a rapid process.
Put it right by describing weathering and sedimentary sequestration as slow carbon cycle transfers operating over geological timescales.
Overlooking the sere scale.
Put it right: Ensure you can explain how carbon dynamics change as a plant community undergoes ecological succession.
Exam tips
- Explicitly link specific flows to their spatial scales, such as photosynthesis to the plant scale and weathering to the continental scale.
- Use systems terminology, clearly distinguishing between stores (e.g., oceans) and the transfers or flows (e.g., sequestration) that connect them.
- When evaluating changes in magnitude, consider both the rate (fast or slow) and the volume of the carbon transfer.
Try the lesson
The start of the The carbon cycle: Factors driving change in the magnitude of these stores over time and space, including flows and transfers at plant, sere and continental scales. Photosynthesis, respiration, decomposition, combustion, carbon sequestration in oceans and sediments, weathering. lesson, made from checked teaching notes for this specification point.
Have a go first
Which process transfers carbon from the atmosphere to the biosphere at the plant scale?
Listen
Carbon store magnitudes change over time and space through dynamic flows operating across multiple scales. At the plant scale, photosynthesis removes atmospheric carbon, while respiration returns it. At the sere scale, ecosystems transition over time, altering carbon storage through decomposition and biomass accumulation. At the continental scale, weathering of silicate rocks and combustion of vast forests or fossil fuels drive massive carbon transfers. Carbon sequestration in oceans involves the physical and biological pumps transferring carbon to deep waters, while sedimentary sequestration locks carbon in the lithosphere for millions of years. These interconnected processes continuously alter the balance of global carbon reservoirs. A strong answer earns marks for these points. Explain how photosynthesis and respiration act as opposing flows at the plant scale, regulating local atmospheric carbon. Describe how decomposition breaks down organic matter, transferring carbon from the biosphere to the pedosphere and atmosphere at the sere scale. Analyse the role of combustion, both natural and human-induced, in rapidly transferring carbon from the biosphere and lithosphere to the atmosphere. Detail the process of carbon sequestration in oceans, including the biological pump and physical downwelling. A common slip: Treating weathering as a rapid process. Instead, describing weathering and sedimentary sequestration as slow carbon cycle transfers operating over geological timescales. Exam tip: Explicitly link specific flows to their spatial scales, such as photosynthesis to the plant scale and weathering to the continental scale.
Key words
Say what each word means before you turn the card.
Spatial and temporal scales
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System flows and transfers
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See every definition
- Spatial and temporal scales
- Flows and transfers operate at plant, sere and continental scales, changing the magnitude of stores over time and space.
- System flows and transfers
- Photosynthesis, respiration, decomposition, combustion, carbon sequestration in oceans and sediments, and weathering move carbon between stores.
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