We don't want to go back to those levels of carbon in the atmosphere. Doing so would completely disrupt every ecosystem in the world. As pointed out already, ca

We don't want to go back to those levels of carbon in the atmosphere. Doing so would completely disrupt every ecosystem in the world. As pointed out already, carbon neutral refers to a time scale that is in the order of at most a few decades. Anything longer than that would have severe ecological effects.