This egested material can be broken down during the process of decomposition. Egestion – the removal of faeces from an animal that will contain carbon.This excreted material can be broken down during the process of decomposition. Excretion – when waste is removed from the body (urine).Combustion – the burning of fossil fuels releases stored carbon dioxide into the atmosphere.These organisms build up and, if compressed over millions of years, can form fossil fuels (coal, oil or gas). Fossilisation – if conditions are not favourable for the process of decomposition, dead organisms decay slowly or not at all.Respiration – when living organisms (plants, animals and decomposers) respire they release carbon dioxide into the atmosphere (this is a form of excretion close excretion Process by which waste products from chemical reactions in an organism are removed.).Feeding – moves carbon in the form of biological molecules along the food chain.This is the only process in the cycle that decreases the level of carbon dioxide in the atmosphere. Photosynthesis – plants absorb carbon dioxide from the atmosphere and form it into sugar, starch and other organic compounds.