Deep Ocean (40,000 billion tonnes of carbon)
Coal, oil, gas (3,300 billion tonnes of carbon)
Soil and organic matter (1,600 billion tonnes of carbon)
Vegetation (600 billion tonnes of carbon)
Atmosphere (750 billion tonnes of carbon)
Sediments and sedimentary rock (1,000,000,000 billion tonnes of carbon)
Ocean surface (1,000 billion tonnes of carbon)
Soil contains a lot of carbon in the form of dead plant material and in the many bacteria and other small organisms that live there.
Exchange of carbon dioxide between the ocean and the atmosphere takes place at the surface.
Plants store carbon as carbohydrates made from carbon dioxide from the atmosphere. Land plants take up about a quarter of all carbon dioxide that enters the atmosphere.
Carbon has been locked up in fossil fuels, built up from once-living things, for millions of years.
Carbon in the atmosphere is mostly in the form of carbon dioxide with some methane and hydrofluorocarbons. The amount of carbon dioxide in the atmosphere is increasing.
The carbon cycle overlaps the rock cycle. Ocean sediments and the rocks they turn into contain huge amounts of carbon. This is mostly in calcite and limestone.
Most of the carbon entering the ocean ends up in the deep ocean where it can be carried by currents for hundreds of years or be lost in sediments.
