[bagacrap]

CO2 from fossil fuels can also be reabsorbed by plants. If you grow a forest, chop it down, bury the logs, then it's underground again. Although, not sure why you need it to be underground as long as it's not in the air.

[redisman]

If it's just sitting above the ground then bacteria will eat it and release the carbon as emissions. OR it burns and then turns into emissions.