Carbon dioxide is a chemical compound composed two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere as a gas. It is currently at a concentration of approximately 385 ppm by volume in the Earth's atmosphere. Carbon dioxide's chemical formula is CO2.
In general, it is exhaled by animals and utilized by plants during photosynthesis. Additional carbon dioxide is created by the combustion of fossil fuels or vegetable matter, among other chemical processes.
Carbon dioxide is an important greenhouse gas because of its ability to absorb many infrared wavelengths of the sun's light, and because of the length of time it stays in the Earth's atmosphere. Due to this, and the role it plays in the respiration of plants, it is a major component of the carbon cycle.
In its solid state, carbon dioxide is commonly called dry ice. Carbon dioxide has no liquid state at pressures below 5.1 atm.