Per this article, the Medieval Warm Period was about 2-3 degrees Fahrenheit warmer than the current average warm temps for Europe. Thus that increase won’t cause the world to end, it will just open a wider range for crops. And then the Medieval Cold period came for the next 150 years.
https://www.sciencedirect.com/topics/earth-and-planetary-sciences/medieval-warm-period
Yup, the re-grrrreta-bulls will not like that phase/cycle.