Volcanos put out more co2 than all people combined plus the rotation and distance of the sun, normal temperature fluctuations like ice ages and the sun gets hotter over time period. Plus mars has a lot of co2 and is cold and volcanic winter is caused by mostly co2. Co2 can trap heat and block it as well thus trapping cold. It's part of the carbon cycle and is why we have oxygen and breathable air. Oil also isn't a fossil fuel it's renewable and abiotic and artificially scarce like diamonds.