Since the Dark Ages happened many decades AFTER the German takeover, they are not connected.
A Fimbulwinter is not exactly a climate change ~ it's just an adverse winter weather pattern that lasts beyond one season. Things always return to normal!
Of course, that one was bad enough that everything got eaten and then they burned everything down to keep warm. When the Bretons arrived in France from Great Brittain in the 7th Century they observed that there were no people and few animals. In fact, it is claimed that the great magician Merlin had to replant all the grapevines in Beaujolais! The Carvajal clan penetrated all the way to the Jura mountains without encountering any other people. Obviously the invading barbarians had been destroyed by this disaster. In due course Ireland became the center of Christian thought, action and missionary work for Western Europe.
Very interesting. This is not an approach I've encountered before, but it's certainly not something I'll dismiss out of hand.
I appreciate your time!
Oh, can you recommend a book on the subject that I might find in my library?