I would add that 'global temperature' means more than the contents of the two words 'global' and 'temperature'.
GHGs cause more of the sun energy to be 'absorbed/transferred' to the climate cycle. Temperature in degrees is the units used IMO because it is more familiar to the general populace.
http://www.numberwatch.co.uk/Temperatures.htm
There was a better paper called 'Is there an average global temperature?' that used to be on 'Google scholar under 'average global temperature' search can't find it now...? I did post it a while back.
So 2-3C is really a measurement of 'actual air temperature' that you would feel. It calculated from the amount of 'energy' added to climate cycles and temperature units ie degrees C are used.
IMO 'AGW' is a terrible misnomer that causes confusion.
