Absolutely correct. That is why we have to resort to computer models. But those are apparently very complicated, and they don't necessarily provide useful, accurate results yet. Improving those computer models is an ongoing process. Presumably, they will eventually match reality sufficiently well to be useful. Probably not yet.
Fortunately, the SO2 injection technique will probably, and simply, counteract whatever increases in CO2 that are likely to occur in the future.
Jim Bell