Carbon dioxide (CO2) is an important trace gas in Earth's atmosphere. CO2 is a greenhouse gas and plays a vital role in regulating Earth's surface temperature through the greenhouse effect.[1] Carbon dioxide is an integral part of the carbon cycle, a biogeochemical cycle in which carbon is exchanged between the Earth's oceans, soil, rocks and the biosphere. Plants and other photoautotrophs use solar energy to produce carbohydrate from atmospheric carbon dioxide and water by photosynthesis. Almost all other organisms depend on carbohydrate derived from photosynthesis as their primary source of energy and carbon compounds.