Carbon dioxide (CO2) is made up of carbon and oxygen and is minuscule (0.0003%) in air. It is produced commercially as a by-product in industrial production processes, such as in power plant stacks. It passes from a gaseous state directly to a solid state ("dry ice") at a temperature of 78.5ºC, and is considered an efficient and safe cooling device.
In recent decades, there has been an increase in the concentration of carbon dioxide in the atmosphere. This increase is due both increased industrial production and reduced vegetation and forests. Carbon dioxide is considered one of the "greenhouse gases" that cause global warming. According to the Kyoto Protocol, all countries of the world are required to act to reduce their carbon dioxide emissions.