by Dr. Ed Berry
Let us look at temperatures. Here is a plot of the reconstructed temperatures and CO2 concentrations for the past 600 million years.
We observe that CO2 is near its lowest concentration for the past 600 million years. Historically, CO2 concentration has been much higher than it is now. We know there was no runaway heat effect or we would not be here.
About 450 million years ago the temperature dropped significantly even though the CO2 concentration was about 12 times higher than today. This disproves the hypothesis that CO2 causes global warming.