Summary
Carbon moves between atmosphere, organisms, oceans and rocks via photosynthesis, respiration and combustion.
In depth
Photosynthesis removes CO2, respiration, decomposition and combustion return it. Oceans absorb CO2, forming carbonic acid, and shells and fossil fuels store carbon for long periods. Burning fossil fuels moves carbon from slow geological pools to the atmosphere, raising CO2 from about 280 ppm before industry to over 420 ppm.
The fast cycle involves photosynthesis and respiration; the slow cycle involves weathering and geological processes. Methane from wetlands and livestock is another flux. Seasonal CO2 wiggles in the Keeling curve reflect Northern Hemisphere growth.
Key idea: fossil fuel burning adds carbon faster than natural sinks absorb it.
The fast cycle involves photosynthesis, respiration and ocean exchange, moving about 100 gigatonnes of carbon per year, while the slow cycle involves rock weathering, burial and volcanism over millions of years. Pools are the atmosphere (about 880 gigatonnes of carbon), vegetation and soils (over 3000), oceans (about 38,000) and fossil fuels and rocks.
Burning fossil fuels and deforestation add around 10 gigatonnes of carbon a year, and CO2 has risen from about 280 ppm before industry to over 420 ppm. Oceans take up about a quarter of emissions, causing acidification that threatens corals and shell-forming plankton, and land takes up another quarter. Methane is a more potent but shorter-lived greenhouse gas.
Example: peat bogs and permafrost store huge carbon pools, which could be released by drainage or thaw.
Frequently asked questions
What is Carbon Cycle?
Carbon moves between atmosphere, organisms, oceans and rocks via photosynthesis, respiration and combustion.
Which area of biology covers Carbon Cycle, and how advanced is it?
Carbon Cycle is one of the 54 topics in Ecology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Climate Change Ecology, Nitrogen Cycle, Water Cycle.
Can you give an example of Carbon Cycle?
Forests act as carbon sinks while growing.
What should I learn before Carbon Cycle?
Carbon Cycle is a Beginner topic, so no earlier topic is required. Other Beginner topics in Ecology that pair well with it include Ecology, Ecosystem, Biotic and Abiotic Factors.
What topics are related to Carbon Cycle?
The closest topics to Carbon Cycle are Climate Change Ecology, Nitrogen Cycle, Water Cycle, Eutrophication. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Carbon Cycle?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Carbon Cycle. To practise the whole of Ecology, use the Ecology quiz.
How is Carbon Cycle different from Climate Change Ecology?
Carbon Cycle: Carbon moves between atmosphere, organisms, oceans and rocks via photosynthesis, respiration and combustion. Climate Change Ecology: Warming shifts species ranges, phenology and interactions, creating mismatches in ecosystems. Read both side by side and note what each one explains.
How should I study Carbon Cycle step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Climate Change Ecology and explain the difference aloud. Finally, take the Ecology quiz and come back to this page for any question you miss.