"...the widely accepted values for temperature increase associated with a double of CO2 were far too high, i.e. 2-4.5 Kelvin. This new peer-reviewed paper claims a value of 1.1 +/- 0.5 K increase,..."
In other words, if we were to double atmospheric CO2 from the current level of 380 ppm to 760 ppm, the global temperature would warm by about 0.6 to 1.6 degrees Celcius. That's right: in the worst case, 1.6°C. (Degrees Kelvin are the same size as degrees Celcius.)
And it's taken us how many centuries to raise the level of atmospheric CO2 by a mere 100 ppm? Doubling it is going to take quite some time.
Anyway, there have been other mentions that doubling the CO2 won't result in as big an increase as the prior doubling, even assuming that CO2 is causing any warming in the first place--which is in doubt, itself, since the ice core data shows CO2 levels lagging the temperature increase rather than leading it.
We don't know why the Earth is warmer now than it was in 1900, 1800, or 1700. We don't know.
Must be all that spitting.