First off, I have not read this book. I just now came across it on Amazon.
I just wonder how the author reconciles certain aspects of his analysis. I'm sure a very convincing case can be made that every 1500 years there is a warm period on Earth. But this was in the absence of an indistrialized human society. In the past, volcanoes could spew CO2 and dust into the air, affecting climate, but the CO2 would eventually dissipate and it would be a very temprorary situation. On the other hand, the way humans emit CO2 is steady and ever increasing. In the past, CO2 did not drive climate. In fact it was the other way around. Climate would drive atmospheric CO2 levels. But now, we have a different situation: a steady and accelerating emission of CO2 into the atmosphere.
What effect this has on climate, I don't know. But to base predictions of the future on a past that did not have an industrialized human society is not the way to go.