A couple of things; first, the "this is all natural" thing is wishful thinking. There's absolutely no evidence that this is the case.

Second, it doesn't strike me as extremely rational to believe that we can pump literally millions of tons of chemicals into the atmosphere and think that nothing will happen.

On cap and trade, we already do it for sulphur dioxide to control acid rain. It works, it hasn't driven anyone out of business, and it hasn't made any nation any poorer. If anything, it helps generate wealth by creating a new markets complete with new technologies. This isn't some wildly speculative economic/environmental theory, it's a tested method that's shown real world results.