This seems like a stealthy move to lend more credance to current global warming by saying that GW was real back then when we had virtually zero industrialization-- so IT MUST BE REAL now that we have so much.
I don't buy this at all. I'm going to need a lot of peer review and corroboration before I even consider taking this seriously.
If prmitive agrarians could raise the global temperature by a single degree, then we should be literally broiling right now.
Not really. Industrialization results in mostly increases in CO2. The main greenhouse gas in the "early global warming" theory is methane, which is a far more powerful "warming" gas than CO2.
I can see the foaming at the mouth Gaia worshippers going off on this one. The ones who spout off "Humanity is a virus infecring the earth mother goddess Gaia".
We all contribute to global warming every time we open the door of our temperature controlled 72 degree environment we call home, and let the heat out.
Now we could all play cave man and test that theory.
On second thought, civilized people need not freeze to death so I am kinda fond of global warming.