How climate evolved on the terrestrial planets

It is argued that the difference in the climates of Venus, earth, and Mars is due largely to differences in their ability to cycle CO2 between the crust and atmosphere. It is suggested that the earth has always had a moderate climate primarily because its cycling mechanism increases the amount of CO2 in the atmosphere when the surface of the planet cools and reduces the amount when the ground temperature rises. Mars is now frozen because it has lost the ability to cycle the gas back into its atmosphere, and Venus is a hothouse because it has no way of removing CO2 from its atmosphere.