A carbon sink (kolsänka) is a natural or human-made process or place where carbon dioxide is absorbed from the atmosphere and stored for a long period of time. Carbon sinks play an important role in reducing the amount of CO₂ in the atmosphere and helping mitigate climate change.
Examples of carbon sinks include forests, oceans, peatlands, and agricultural soils. Wood used in buildings, furniture, and similar products is also sometimes referred to as a carbon sink in the sense that it stores carbon absorbed during tree growth.