The main problem is that we've released so much, so fast, that there really isn't a productive place for it to go. The other problem is that humanity keeps expa

The main problem is that we've released so much, so fast, that there really isn't a productive place for it to go. The other problem is that humanity keeps expanding and there's not much free space left for nature preserves. If you wanted to plant a new rainforest, where would you possibly put it? We're already cutting down swathes of existing ones just to feed and house our expanding populations. So sadly, most of that extra carbon just remains in the air.