What Does 2000 Years of Temperature Data Tell Us?

NOTE: This piece by Willis Eschenbach is reposted here with his permission.

I got to thinking about how little the atmospheric CO2 level has changed over most of the last two thousand years. Here is the CO2 data from ice cores (colored dots) and from the Mauna Loa CO2 measuring stations (red/black line).

Figure 1. Ice core CO2, and Mauna Loa instrumentally-measured CO2.