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Carbon dioxide Sinks - Rocks and Fossil Fuels

The calcium carbonate cliffs of Dover and the petrol at motorway service stations, both these substances represent large geological reservoirs of carbon and, as such, long term carbon sinks.

Rates of formation of fossil organic carbon (fossil fuel) are very slow, and dwarfed by the rate at which they are currently being consumed by man. Current burning of fossil fuels by man is releasing an estimated 5.3 thousand million tonnes of carbon back into the atmosphere each year.

The formation of rock carbonates, such as the chalk of Dover, is also very slow and is unlikely to match the use of this carbon sink by man in cement production. At present, around 100 million tonnes of carbon is released to the atmosphere each year from use of this geological carbon reservoir.

Some of the carbon, in such geological reservoirs as chalk and fossil fuels, is released due to volcanic action. Global emissions from this source can vary greatly from year to year depending on levels of volcanic activity, but on average about 100 million tonnes of carbon is reintroduced to the atmosphere each year via this pathway.


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