Thanks, Alex, for your thoughtful reply. I have a few comments...

Thanks, Alex, for your thoughtful reply. I have a few comments and questions.

1. I have quite often seen the second chart you depicted, but do not know the third. Would you please explain it further? Let me know its source so I can pursue it further, please. Incidentally, what method/s are used to determine prior solar insolation? (Also your comment: As I said in an earlier post, CO2 has been much higher in the past (as you've quoted, 4000ppm) and the earth didn't fry! Firstly, Solar output was about 4.5% weaker. It should have been enough to cause an ice age, yet the earth was much hotter than it is today. Over what period was that 4.5%?)
2. The 800 year time lag – why the difference between northern and southern hemispheres? Does this difference indicate that CO2 levels are not a predictor, and not the primary cause, of warming? I do not dispute that CO2 is a greenhouse gas, nor that sensitivity (the effect of CO2 levels on water vapour levels) is significant. However, the climate is indeed highly complex as we know, and we are still needing more research on the drivers as well as inhibitors of insolation.
3. I agree about the significance of the Milankovitch cycles; the tilt in particular explains for me much of what we know of human civilisation in its changing environment over the last 3000 years and more.
4. Berners conclusion is "Nevertheless, the overall trend remains. Thismeans that over the long term there is indeed a correlation between CO2 andpaleotemperature, as manifested by the atmospheric greenhouse effect". I accept the qualification that CO2 values “are susceptibleto modification”, but I don’t consider this statement to be consistentwith the second chart you posted, nor with his whole conclusion.
5. What are your sources for your statement: As CO2 levels in the atmosphere rose, over the next few 1000 years, CO2 and other greenhouse gasses took over as the predominant cause of warming. (Positive feedback)? We have had a few warming periods over the last few thousand years, periods warmer than now; I'm thinking in particular of the Minoan, Roman and Medieval periods. And then of course the Little Ice Age which peaked I think at around 1780 AD.
   Do you know what the CO2 levels were over this period shown in this chart? Incidentally, I note that the rate of warming for the Medieval Period has a slope rather similar to ours post 1980. (And as another poster commented, I remember the reports of scientists in the early 1970s, forecasting we were heading for an Ice Age sooner than expected.)
6. Now, just because an increase in temp puts more CO2 into the atmosphere, which is true, doesn't preclude CO2 also causing temperatures to rise. Yes, but correlation is not causation. Further, there can often be a number of causes, each of different significance. It seems to me that we are simply laying the cause at the feet of CO2 alone.
7. I have a number of reflections about the whole climate debate, policy implications, geopolitical differences, energy derivation and deployment, human nature, group think . . . but these are for some other time.
   

I look forward to your thoughts on the above.