Since the plates aren't much different today than they were 50 million years ago, the elevated CO2 levels of 50 million years ago shouldn't have allowed for the planet to cool since you are claiming that elevated temperatures today (which are 2 to 3 times less than in the past) will cause temperatures to rise today.The most popular theory for that long term cooling is plate tectonics. Please explain how cooling from plate tectonics makes it impossible for CO2 and the greenhouse effect to warm the planet?