I was surprised that the relationship between CO2 and GMST was so linear past around 1200AD. What's really weird is I don't see the expected acceleration due to the industrial revolution in the 1800s. The chart seems to imply its a function of population more than technology?
Are you referring to the IPCC chart in the post? Or another chart? If so, maybe shoot me a link? The chart in the post starts at 1850.
I wrote about the analysis of past models and how they can take advantage of data and markets to be better.