Here I am in a full-blown debate about the reality of global warming, something I swore I wouldn't do. I regret getting dragged into this like potato salad that's been sitting outside at a picnic for 8 hours.

I shouldn't have engaged because your post has nothing to do with aviation, and again, if you want to debate global warming or something like the philosophical basis of human individual moral culpability, there are better venues on the internet.

To that end, I'll try to keep my response brief:
-The MWP wasn't global
-It wasn't rapid
-It wasn't as severe as the warming we've already experienced in places such as Alaska (for instance, there are plenty of spots in Alaska where temperatures are up close to 5 degrees C over the past decade)
Temperature Changes in Alaska | Alaska Climate Research Center

A decent summary:
https://skepticalscience.com/medieval-warm-period.htm

If you're interested in a more state of the art scientific discussion:
https://advances.sciencemag.org/cont...00806.full.pdf