Rog, your plot shows that when Carbon Dioxide levels were higher, there was significant global warming.
You've just contradicted your main premise.
But, that's so long ago, and way before the ice cores, and conditions were way different than now, it's hard to make any conclusions about how raising the Carbon Dioxide level today will change climate.
And, the farther back you go, the less accurate the data is.
Since we're re-posting old plots, here's the plot that shows ice core data:
In the last 400,000 years, except for the last few years, the Carbon Dioxide levels were between 180 and 300 PPM. We're at about 390 PPM right now.