Yup, the real science is settled - no further increase in CO2 concentration will have any effect on temperature. That radiative window is already completely closed off by the concentration that has existed for the last several thousand years.
Now, as to erring on the side of caution - well, maybe we should. NUKE CHINA NOW! And those rambunctious Aussies may very well cause problems after we do that - so NUKE AUSTRALIA NOW!