There's a good book called "The Little Ice Age" (2001) by a guy named Fagan available from Amazon, if you haven't already read it. The book also describes the Medieval Warm Period when grapes grew in England and English vintners competed with the French.
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I'll add a data point there:
Somewhere around the sixth century, the entire volcanic caldera known as Krakatao in Indonesia exploded, in an eruption larger by several magnitudes even than its massive eruption in the 1800's, which destroyed lives and villages for 50 miles in every direction.
The earlier eruption obliterated several hundred square miles of land, returning most of what had been been the island from which Krakatau rose - into the Pacific Ocean.
The resulting dust cloud which was driven miles into the atmosphere, radically altered climate around the globe for several years following the explosion, leading to the so-called "dark ages".
The flea which carries the Bubonic Plague, requires a cool, very specific temperature range to carry the Plague. As temperatures around Europe dropped in the years following Krakatau's explosive eruption, the black death reared its ugly claws and tore through the Western world.
Global temperatures rise, and fall. The sun is the primary driver.
Behind the sun, volcanos are far far more signifant as potential climate drivers, than humans throughout our entire history.
IMHO.