What is the relationship between carbon dioxide (CO2) levels and pH in a given system?

The relationship between carbon dioxide (CO2) levels and pH in a system is that higher levels of CO2 can lower the pH of the system, making it more acidic. This is because CO2 can react with water to form carbonic acid, which then releases hydrogen ions, leading to a decrease in pH. Conversely, lower levels of CO2 can result in a higher pH, making the system more basic.