Anthropogenic CO2 emissions
CO2 reuse without transformation and biologically

CO ₂ (carbon dioxide) is a stable and relatively chemically inert molecule: it represents the ultimate degree of oxidation of carbon.

The oxidation of carbonaceous matter, whether of organic or inorganic origin such as coals, can be due to a thermal (combustion, incineration), biological (biodegradation, usually by aerobic micro-organisms) or chemical (reaction with an oxidant) effect. [G1815].