Some carbon dioxide, or CO2, is needed for life processes. We can call this “Regular CO2.” But CO2 is not just something that plants breathe in and we breathe out.
It’s also something that gets put into the atmosphere when burn fossil fuels for transportation or manufacturing. And these things are putting a lot of CO2 into the atmosphere and ocean. We can call this “Rampant CO2” because there is too much of it and it’s getting out of control.
By using the distinction between Regular and Rampant CO2, you can help your visitors easily add to the knowledge they probably already hold about carbon dioxide—that it plays a role in human respiration and photosynthesis. The taxonomy allows them to hold the newer, counter-intuitive information (that CO2 can also play a harmful role) alongside existing concepts.