Looking at ancient civilizations is always fun, but did you know that the Romans enjoyed a significant warm period which allowed them to feed their empire (using slaves to do the dirty work, obviously)?
Things cooled down, and the empire declined. A random link:
https://climatechangedispatch.com/roman-warm-period-3-6f-warmer-than-today-new-study/
"The Mediterranean Sea was 3.6°F (2°C) hotter during the Roman Empire than other average temperatures at the time, a new study claims.
The Empire coincided with a 500-year period, from AD 1 to AD 500, which was the warmest period of the last 2,000 years in the almost completely land-locked sea.
The climate later progressed towards colder and arid conditions that coincided with the historical fall of the Empire, scientists claim."
2°C warmer than now. This was a good thing for the Roman Empire, but spells catastrophe for us. Hmm. ...