There's no 'right' and no wrong in science, as I've attested to on here any times.there is no proof, though deniers want there to be. The best you'll get is a consensus amongst scientists. In this case, the consensus is huge, at 99.9% in the latest literature survey. What does that suggest about CO2 being the major cause of global warming.

A good analogy is gravity. The theory of gravity is not proven and never will be. However, if I was stood under a falling piano, I'd be inclined to do my best to get out of the way. A denier, however would be still telling anyone in hearing distance that the theory is a bunch of crap. Right up to the end. 😀