Carbon cycle

Part of a series on the
Carbon cycle
By regions Terrestrial Marine Atmospheric Deep carbon Soil Permafrost Boreal forest Geochemistry
Carbon dioxide In the atmosphere Ocean acidification Removal Satellite measurements
Forms of carbon Total carbon (TC) Total organic carbon (TOC) Total inorganic carbon (TIC) Dissolved organic carbon (DOC) Dissolved inorganic carbon (DIC) Particulate organic carbon (POC) Particulate inorganic carbon (PIC) Primary production marine Black carbon Blue carbon Kerogen
Metabolic pathways Photosynthesis Chemosynthesis Calvin cycle Reverse Krebs cycle Carbon fixation C3 C4
Carbon respiration Ecosystem respiration Net ecosystem production Photorespiration Soil respiration
Carbon pumps Biological pump Martin curve Solubility pump Lipid pump Marine snow Microbial loop Viral shunt Jelly pump Whale pump Continental shelf pump
Carbon sequestration Carbon sink Soil carbon storage Marine sediment pelagic sediment
Methane Atmospheric methane Methanogenesis Methane emissions Arctic Wetland Aerobic production Clathrate gun hypothesis Carbon dioxide clathrate
Biogeochemical Marine cycles Nutrient cycle Carbonate–silicate cycle Carbonate compensation depth Great Calcite Belt Redfield ratio
Other Climate reconstruction proxies Carbon-to-nitrogen ratio Deep biosphere Deep Carbon Observatory Global Carbon Project Carbon capture and storage Carbon cycle re-balancing Territorialisation of carbon governance Total Carbon Column Observing Network C4MIP CO2SYS
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The carbon cycle is that part of the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of Earth. Other major biogeochemical cycles include the nitrogen cycle and the water cycle. Carbon is the main component of biological compounds as well as a major component of many minerals such as limestone. The carbon cycle comprises a sequence of events that are key to making Earth capable of sustaining life. It describes the movement of carbon as it is recycled and reused throughout the biosphere, as well as long-term processes of carbon sequestration (storage) to and release from carbon sinks.

To describe the dynamics of the carbon cycle, a distinction can be made between the fast and slow carbon cycle. The fast carbon cycle is also referred to as the biological carbon cycle. Fast carbon cycles can complete within years, moving substances from atmosphere to biosphere, then back to the atmosphere. Slow or geological cycles (also called deep carbon cycle) can take millions of years to complete, moving substances through the Earth's crust between rocks, soil, ocean and atmosphere.^[2]

Humans have disturbed the carbon cycle for many centuries. They have done so by modifying land use and by mining and burning carbon from ancient organic remains (coal, petroleum and gas).^[1] Carbon dioxide in the atmosphere has increased nearly 52% over pre-industrial levels by 2020, resulting in global warming.^[3] The increased carbon dioxide has also caused a reduction in the ocean's pH value and is fundamentally altering marine chemistry.^[4]