I'm not a qualified climate scientist, are you? I doubt Rocks or sealy are either.
Why bother playing armchair scientist, when none of us are remotely qualified to do so? Saying that incremental increases in gases should have no effect is sheer uninformed punditry, baseless speculation.
Science informs us that small, incremental increases in the mercury or arsenic content of your drinking water would increase your risk of cancer or death by orders of magnitude.
On what basis do you speculate that small increases in greenhouse gas content wouldn not upset the delicate equilibrium of the atmosphere? I'm sure actual climate scientists, with years of training in the subject, would know better than you or me.