The Ocean as a Carbon Sink

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Carbon Sink Noun

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[kar-buhn singk]

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Carbon Sink

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A natural environment that absorbs and stores more carbon from the atmosphere than it releases, such as the ocean.

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Example: This diagram shows carbon dioxide (CO2) from the atmosphere, produced by factories, dissolving into the ocean, which acts as a large carbon sink.

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Carbon Reservoir Noun

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[kar-buhn rez-er-vwahr]

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Carbon Reservoir

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A component of the Earth system where carbon is stored, such as the deep ocean, atmosphere, or marine life.

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Example: This diagram shows major carbon reservoirs like the atmosphere, land, and ocean. Arrows illustrate how carbon dioxide (CO2) moves between these storage areas.

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Carbon Flux Noun

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[kar-buhn fluhks]

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Carbon Flux

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The flow or rate of exchange of carbon between different reservoirs, measured in gigatons of carbon per year.

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Example: This diagram shows carbon flux, the movement of carbon. Carbon from sources like fossil fuels enters the atmosphere and then flows to sinks, including the ocean.

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Calcium Carbonate (CaCO₃) Noun

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[kal-see-uhm kar-buh-neyt]

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Calcium Carbonate (CaCO₃)

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A chemical compound that is the primary component of the shells and skeletons of many marine organisms like plankton.

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Example: This seashell is made of calcium carbonate, a compound that marine animals build by taking carbon from ocean water and storing it in their shells.

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Solubility Noun

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[sol-yuh-bil-i-tee]

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Solubility

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The ability of a gaseous substance, like carbon dioxide, to dissolve in a liquid, which is affected by temperature and pressure.

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Example: This diagram shows that gases are less soluble in hot water than in cold water, a key principle for how oceans absorb atmospheric CO2.

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Carbonate Compensation Depth (CCD) Noun

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[kar-buh-neyt kom-pen-sey-shuhn depth]

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Carbonate Compensation Depth (CCD)

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The ocean depth below which calcium carbonate dissolves faster than it can accumulate on the seafloor.

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Example: This diagram shows that as carbonate particles (like shells) sink in the ocean, they dissolve below a certain depth, the Carbonate Compensation Depth (CCD).

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Calcareous Sediment Noun

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[kal-kair-ee-uhs sed-uh-muhnt]

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Calcareous Sediment

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Seafloor sediment composed primarily of the calcium carbonate shells of dead marine organisms, found above the CCD.

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Example: This microscopic image shows the calcium carbonate shell of a foraminifera, a tiny sea creature. These shells accumulate on the ocean floor, forming calcareous sediment.

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Siliceous Sediment Noun

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[si-lish-uhs sed-uh-muhnt]

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Siliceous Sediment

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Seafloor sediment composed of silica-based remains of organisms, typically found below the CCD where carbonate has dissolved.

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Example: This map shows where siliceous sediment (green areas) accumulates on the ocean floor, often in nutrient-rich zones like the Antarctic and equatorial Pacific.

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Solubility Carbon Pump Noun

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[sol-yuh-bil-i-tee kar-buhn puhmp]

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Solubility Carbon Pump

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The inorganic process that transports dissolved carbon from the ocean's surface to the deep ocean via sinking cold water.

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Example: This diagram shows how carbon dioxide (CO₂) dissolves in the ocean's surface, is 'pumped' to the deep ocean by currents, and is stored for long periods.

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Biological Carbon Pump Noun

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[bahy-uh-loj-i-kuhl kar-buhn puhmp]

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Biological Carbon Pump

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The process where marine organisms take up carbon for organic matter and shells, which then sink to the deep ocean.

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Example: This diagram shows how living things "pump" carbon from the air into the deep ocean. Phytoplankton take in CO2, are eaten, and when they die and sink, they carry that carbon to the ocean floor.