A gas (chemical formula CO2), which occurs naturally in the Earth’s atmosphere. A gas (chemical formula CO2), which occurs naturally in the Earth's atmosphere. Carbon dioxide is given off by organisms when they respire, and it is absorbed by organisms like plants and... More is given off by organisms when they respire, and it is absorbed by organisms like plants and algae during A chemical process that takes place in living cells, by which some living organisms (such as green plants and algae) convert energy in sunlight into chemical energy. The compounds produced... More*. Carbon dioxide is a A gas found in the earth's atmosphere that traps heat radiated from the surface of the earth, and causes the earth's temperature to rise. The term comes from the fact... More. Carbon dioxide is a key part of the Describes how carbon moves around the environment. It is an example of a biogeochemical cycle. See also carbon flux. In recent years the carbon cycle has been studied intensively in order to... More.