Introduction to Carbon and Carbon Stores

Carbon is an essential element to all living things on earth – plants and animals, surface and marine. It also plays a major role in regulating global climate, particularly temperature and in determining the acidity of rain, rivers and oceans.

Carbon cycles, like water cycles, should be thought of as a system. There are inputs, stores, fluxes/flows and outputs that transfer carbon from one environment to another and cause stores to be depleted, or accumulate.

Carbon stores (reservoirs): location

The main stores of carbon are located in, and transferred between the:

• atmosphere: mainly as carbon dioxide CO₂ but also shorter-lived methane CH₄
• biosphere: all living organisms are composed of carbon occupying various environments
• cryosphere: the frozen ground of tundra and arctic regions containing plant material
• pedosphere: soil contains much organic carbon and the remains of dead plants & animals
• lithosphere: many of the rocks of the earth’s crust contain carbon, such as chalk/limestone (calcium carbonate)
• hydrosphere: the oceans contain much dissolved CO₂ as well as marine

Carbon stores: magnitude