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It is used by [[plants]] in the process of [[photosynthesis]] to create complex carbohydrates ([[cellulose]] and [[sugar]]s), using water and the [[energy]] from [[sunlight]].  The waste product in this process is [[oxygen]].

It is used by [[plants]] in the process of [[photosynthesis]] to create complex carbohydrates ([[cellulose]] and [[sugar]]s), using water and the [[energy]] from [[sunlight]].  The waste product in this process is [[oxygen]].

At room temperature and atmospheric [[pressure]], carbon dioxide is a gas. It becomes solid at -78 ºC at standard atmospheric pressure, forming dry ice. When it thaws, it turns directly into a gas again (called [[sublimation]]). <ref>"Dry ice is frozen carbon dioxide. A block of dry ice has a surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees C). Dry ice also has the very nice feature of sublimation -- as it breaks down, it turns directly into carbon dioxide gas rather than a liquid." [http://www.howstuffworks.com/question264.htm How Stuff Works] </ref> This can be seen from the phase diagram to the right, where at 1 atmosphere of pressure, there is no liquid state separating the solid and gas as temperature rises.

At room temperature and atmospheric [[pressure]], carbon dioxide is a gas. It becomes solid at -78 ºC at standard atmospheric pressure, forming [[dry ice]]. When it thaws, it turns directly into a gas again (called [[sublimation]]). <ref>"Dry ice is frozen carbon dioxide. A block of dry ice has a surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees C). Dry ice also has the very nice feature of sublimation -- as it breaks down, it turns directly into carbon dioxide gas rather than a liquid." [http://www.howstuffworks.com/question264.htm How Stuff Works] </ref> This can be seen from the phase diagram to the right, where at 1 atmosphere of pressure, there is no liquid state separating the solid and gas as temperature rises.

CO₂ is one of the so-called [[greenhouse gas]]es.  Heat-trapping by CO₂ has been observed on [[Earth]] and [[Venus]].  The extent of its role in the current increase in average global temperatures is a topic of active political and scientific debate. Rising CO₂ levels have also been attributed to the acidification of the world's oceans.  

CO₂ is one of the so-called [[greenhouse gas]]es.  Heat-trapping by CO₂ has been observed on [[Earth]] and [[Venus]].  The extent of its role in the current increase in average global temperatures is a topic of active political and scientific debate. Rising CO₂ levels have also been attributed to the acidification of the world's oceans.