Amateur opinions dont mean much. CO2 is the leading green-house gas other than water vapor which only lasts days in the atmosphere, and can change quickly based on the control from other gases. CO2 still represents a huge portion of the green-house effect and is second to water vapor. Saying 10-25% of the total is small is really stupid, sorry to say. It's not the quantity in concentration that matters, it's the contribution to green-house effect. Even the percentage is not well understood yet, which also points to why research is important.I don't think that multiple amounts of CO2 will make any difference because it is such a small amount in the first place.
Ratch