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 Earth’s carbon cycle—which has not witnessed such a rapid increase in atmospheric carbon dioxide in the past 50,000 years—is without ideology. —Mario Alejandro Ariza, The Atlantic, 18 June 2024

At roughly 200,000 square kilometers, the Pantanal comprises about 3% of the globe’s wetlands and plays a key role in the carbon cycle. —Aditi Sangal, CNN, 14 June 2024

Around 183 million years ago, there was a perturbation in the carbon cycle, along with extreme volcanism that belched out massive amounts of methane, sulfur dioxide, and mercury. —Elizabeth Rayne, Ars Technica, 28 May 2024

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

Word History

First Known Use

1901, in the meaning defined at sense 1

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