The Carbon Cycle Flashcards
What is the carbon cycle?
A closed system where carbon moves between stores (atmosphere, biosphere, hydrosphere, lithosphere) through processes like respiration, combustion, and sequestration.
What are the 4 major carbon stores?
• Lithosphere (rocks, fossil fuels) – 100,000 PgC
• Hydrosphere (oceans) – 38,000 PgC
• Biosphere (living organisms) – 2,000 PgC
• Atmosphere (CO₂ gas) – 750 PgC
What are carbon fluxes?
The movement of carbon between stores, e.g. photosynthesis, respiration, decomposition.
How does limestone form? (Give 5 steps)
1) Marine organisms with calcium carbonate (+ phytoplanktons) shells die
2) sink to the bottom of the ocean floor
3) more sediments fall on it
4) sediment reaches 100m in depth
5) compact under pressure into limestone.
How does coal form? (Give 3 steps)
1) Dead land-based plants settle in swamps
2) compact over millions of years
3) form peat and coal.
How does crude oil form? (Give 3 steps)
1) Organic material in sediments undergoes anaerobic reactions
2) forming crude oil
3) which migrates until trapped by impermeable rock.
How does photosynthesis affect the carbon cycle?
Plants sequester atmospheric CO₂ to produce energy, reducing carbon levels in the air.
How does respiration affect the carbon cycle?
All living organisms respire, releasing CO₂ back into the atmosphere.
How does decomposition affect the carbon cycle?
Decomposers break down organic matter, returning carbon to the soil or atmosphere.
How do phytoplankton contribute to the carbon cycle?
They absorb CO₂ from the atmosphere via photosynthesis, some die and sink, forming carbonate sediments.
How does fossil fuel combustion impact the carbon cycle?
Releases stored carbon (CO₂) into the atmosphere, enhancing the greenhouse effect.
What are the 4 effects of burning fossil fuels on climate?
• Increased global temperatures
• Altered precipitation patterns
• More extreme weather events
• Arctic amplification (faster warming in polar regions)
How does deforestation affect the carbon cycle?
Reduces carbon sequestration by trees and releases stored carbon as CO₂.
What is afforestation?
Planting trees to restore carbon stores and balance the carbon cycle.
What is the natural greenhouse effect?
Greenhouse gases (CO₂, CH₄) trap heat, keeping Earth warm enough to support life.
What is the enhanced greenhouse effect?
Human activities (burning fossil fuels, deforestation) increase greenhouse gas levels, trapping more heat and raising global temperatures.
What is the albedo effect?
Light surfaces (ice, snow) reflect sunlight, while dark surfaces (oceans, forests) absorb heat, affecting temperature distribution.
How do wildfires influence the carbon cycle? (3 things)
• Burn vegetation, releasing stored CO₂
• Reduce forest carbon sinks
• Can promote regrowth, restoring sequestration
How does Arctic warming impact the carbon cycle? (2 things)
• Thawing permafrost releases CO₂ and CH₄
• Melting ice reduces albedo, increasing warming
How does volcanic activity release carbon? (2 things)
• Outgassing of CO₂ from tectonic activity
• Chemical weathering of rocks absorbs CO₂ over time
