After 1250. there was a substantial die-off of humans. Much of that was caused by Bubonic plague, but how much of that was caused by crop-failure-driven poor nutrition making Europeans susceptible to communicable disease is now hard to determine. The English used to make their own wine in the Medieval Warm period. Other less dramatic changes after the end of the Medieval Warm period. By the 1600s, Englishmen used to set up markets on the ice at London, because the Thames would freeze over solid, very solid, in fact.
I have read a bit about the American Civil War, and, while admittedly anecdotal, the ground in Virginia was covered with snow from December through February, and into March during the war. That rarely happens now. The last time that happened in Virginia was 2009, but before that it was quite a while. Something is causing that change.
