How is carbondioxide returned to the atmosphere?

Combustion, respiration

Explanation:

Carbon is the major element in the dry matter of all living things. Respiration by both plants and animals converts some of the organic compounds into carbon dioxide. The latter is released to the atmosphere and reused by green plants.

When plants and animals die, their carbon compounds are converted into carbon dioxide by the action of saprophytic bacteria and fungi. The carbon dioxide is released back to the atmosphere.

When coal, natural gas and oil are combusted as fuels they release carbon dioxide to the atmosphere.

Carbon dioxide is released to the atmosphere through respiration by animals, plants and microorganisms. It is also released by the combustion of wood and fossil fuels (such as coal, oil and natural gas).