Here is an Acid test.
1. Is the Earth's climate warming. Unknown, 120 years of data collected compared to the current climatological epic is insignificant.
2. If the earth is warming is it caused by man. Well, assuming the earth is warming, there are much more powerful forces effecting climate then man.
3. If the Earth is warming and caused by man is it necessarily bad? Historical speaking civilizations have flourished during warming trends and declined during cooling trends. Although there is no way to quantify with hard numbers, using historical texts we have learned that the Romans grew gapes near Hadrians wall (250ad) and the Norse grew oats and barely in Greenland circa ~1000ad. Neither of which could be replicated today. So It could be determined with a fair degree of certainty that the earth has been both warmer and colder during the distant past.
In conclusion. In order for mankind to be concerned with ACW, the earth must be warming due to man made causes and in turn is detrimental to the planet. Maybe one day in the distant future a rational conclusion can me made, but doubtfuly in my lifetime.