EXACTLY my feelings. If there's even a chance we're screwing things up, we need to stop and re-assess! It's better to stop, then discover it was a false alarm*, than realize fifty years down the line that we really screwed ourselves over irreversibly.

*highly unlikely, given the available evidence, but hope springs eternal.

In addition to the medieval history, I took most of a degree in biology, with an ecological systems emphasis. And when I started combining those fields, I saw stuff that scared me. People are very, very bad at maintaining whatever ecosystem they happen to be able to get their hands on - and now that encompasses the entire planet. It's one thing for a city-state of a few thousand people to log off all their forest cover, lose their topsoil, and die of malnutrition (or get taken as slaves by the next nation over) - but we don't have anywhere left to go.