"Fine"? Did the history professor consider anything other than history or politics?
The way global warming and our general destruction of nature is going (not just species or climate but also e.g. depletion of groundwater in a lot of heavily populated areas), I'm not sure democracy will be our biggest concern in 200 years' time.
No, he did not consider things that have never happened before.
He can only extrapolate from events that already happened. Human made global warming is a first time, so difficult to say what will happen from a historical perspective.
Human-made global warming appears to go back to the advent of agriculture, though, so for all intents and purposes it has been a constant throughout the history of which we speak.
