Theoretically, how much warming would a doubling of atmospheric CO2 to 560 ppm cause ......?

Considering that one sample of co2 when i was doing the tests a couple of months ago was close to 6000ppm, maybe a little more and it was less capable of holding heat than ambient air i would have to say things would cool off better at night in low humidity zones. it is not co2 that warms things up it is humidity pure and simple as anyone who has actually performed the experiments will know. Even at concentrations approaching that of nitrogen co2 has a hard time retaining any heat at all. This is why it is one of the very best refrigerants on the market.