This article on a paper claiming that reforestation resulting from depopulation of the New World after the post-Columbian pandemics was a trigger for the Little Ice Age was interesting, if fantastical. IIRC, they still can't agree on something as simple as whether the early voyagers brought back syphilis in the late 15th Century. Building an anthropogenic cause for the Little Ice Age on this sort of rickety foundation seems so amazingly Rube Goldbergish as to be practically impossible to prove. It's the very essence of "Just So" explication.