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carbon cycle
noun
1
: the cycle of carbon in the earth's ecosystems in which carbon dioxide is fixed by photosynthetic organisms to form organic nutrients and is ultimately restored to the inorganic state (as by respiration, protoplasmic decay, or combustion)
2
: a cycle of thermonuclear reactions in which four hydrogen atoms synthesize into a helium atom by the catalytic action of carbon with the release of nuclear energy and which is held to be the source of most of the energy radiated by the sun and stars
Examples of carbon cycle in a Sentence
Recent Examples on the Web
The climate phenomenon limits uptake of atmospheric CO2 by land ecosystems, according to John Miller, a carbon cycle scientist with NOAA’s Global Monitoring Laboratory.
—Tom Yulsman, Discover Magazine, 7 June 2024
These include complex biological and physical systems, such as the nitrogen and carbon cycles; photosynthesis, which creates half of the oxygen that humans breathe and forms the base of the ocean’s biological productivity; and ocean circulation.
—Alan B. Sielen, Foreign Affairs, 15 Oct. 2013
In recognition of the important role the upper levels of the ocean play in helping to regulate the earth’s carbon cycle, the US Department of Energy treats carbon capture from the upper hydrosphere as equivalent to that from the atmosphere in its carbon removal purchase regulations.
—Erik Kobayashi-Solomon, Forbes, 15 Feb. 2024
These microscopic marine algae play a major role in the global carbon cycle.
—Laura Baisas, Popular Science, 8 Feb. 2024
For instance, if there are mass die-offs on the continent, and these corpses become encased in ice rather than sink into the ocean, the deaths could potentially affect the global carbon cycle and nutrient flow.
—Meghan Bartels, Scientific American, 12 Feb. 2024
Historically, climate modelers have focused on how human projects interact with the most obvious components of the carbon cycle: oceans, forests, sea ice, atmosphere, all the grand parts of the global landscape.
—Bathsheba Demuth, The Atlantic, 4 Jan. 2024
The water cycle, nitrogen cycle, the oxygen cycle, the carbon cycle—dust is feeding into all of these.
—Matt Simon, WIRED, 27 Nov. 2023
Chemical weathering can help counteract the continuous carbon dioxide released by the world’s volcanoes and is part of the Earth’s natural carbon cycle.
—Laura Baisas, Popular Science, 5 Oct. 2023
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'carbon cycle.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Word History
First Known Use
1901, in the meaning defined at sense 1
Dictionary Entries Near carbon cycle
Cite this Entry
“Carbon cycle.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/carbon%20cycle. Accessed 15 Jun. 2024.
Kids Definition
carbon cycle
noun
: the cycle of carbon in living things in which carbon dioxide is used in photosynthesis to form food and growth substances and is later returned to the environment by respiration, decay, and burning
Medical Definition
carbon cycle
noun
: the cycle of carbon in living beings in which carbon dioxide is fixed by photosynthesis to form organic nutrients and is ultimately restored to the inorganic state by respiration and protoplasmic decay
More from Merriam-Webster on carbon cycle
Britannica.com: Encyclopedia article about carbon cycle
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