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

This year’s report includes a detailed accounting of how the carbon cycle is changing in the Arctic. —Evan Bush, NBC News, 10 Dec. 2024

Part of the problem is that, unlike weather forecasters who can wait a day to check their predictions, carbon cycle researchers have little ability to directly measure carbon flow to test their models, Michalak said. —Noah Haggerty, Los Angeles Times, 28 Jan. 2025

Losing such water content can lead to a breakdown in the carbon cycle, where silicate weathering stops removing carbon dioxide from the atmosphere, and the planet experiences runaway climate change — the same process thought to have occurred on Venus, which may once have been habitable. —Tom Brown, Space.com, 6 Jan. 2025

At the core of the carbon cycle is photosynthesis, where plants, algae and select bacteria transform atmospheric CO2 into organic compounds using sunlight. —Sahit Muja, Forbes, 17 Oct. 2024

Word History

First Known Use

1901, in the meaning defined at sense 1

Rhymes for carbon cycle

• recycle
• motorcycle

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