Its atmosphere is 100 times less dense than Earth's and allows outgoing heat to slip through easily. Even though Mars' atmosphere is about 95% CO2, there is too little atmosphere to have a marginal effect. Mars is also the fourth planet in the solar system and receives less solar energy from the sun than Venus and Earth. All these properties culminate in temperatures of around -60 C. The Earth is essentially the middle man in this comparison. The atmosphere is neither too thick nor too thin and is not made up of a huge amount of greenhouse gases. The sun does not give the Earth too much energy nor too little. This allows for a comfortable temperature for life to develop, what astronomers consider a "Goldilocks planet." Greenhouse gases contribute to a planet's temperature based primarily on the density of its atmosphere. Both Venus and Mars have atmospheres made up mostly of greenhouse gases, but they have very polarized temperatures. The key difference is that Venus has an atmosphere 1000 times denser than Mars, which makes Venus incredibly hot and Mars a little cold. In short, it makes no sense to remove CO2 from the ground and put it into the atmosphere, in the terrestrial context. Our atmosphere is perfect to the point of being susceptible to fluctuations in the greenhouse effect