[Virology] The use of CO2 in cell culture incubators

[tim]

Hello, we are in a debate over the reason why cell culturing requires
CO2 incubators. The quesiton is does carbon dioxide (gas) in the
incubator slow the carbonic acid disassociation to H ion and HCO3, thus
maintaining the pH of the cell medium.  If anyone has the answer as to
why we use carbon dioxide in cell culturing please advise...
Thanks
two grad students