In answer to WBardwin: As to a good source on effects of Little Ice Age, my background is of decades of taking field archeology classes, while living in the area of the "anasazi".  None of the things I could cite are in writing, such as books, it comes from lectures.  Of course, the "anasazi" did not leave written records, or the entire subject would be much more clear.  
Currently I teach ceramics (pottery) at Eastern Arizona College.  I make "anasazi" reproductions that everyone raves about.  I could say I am the incarnation of an "anasazi", which I personally believe, and it would be taken with the same disbelief as suggesting that the Little Ice Age (please see the Wikipedia article on this subject)could be causative to the abandonment of the "anasazi" homelands.  
A New York Times article of this date (Vanished: A Pueblo Mystery)does mention Little Ice Age, but generally dismisses it as causal, preferring a way more complicated explanation.  Unfortunately the field is filled with a LOT of subjective information, even or perhaps especially, by the "experts".  I do believe that a mention IS in order, even if others disagree, particularly since it IS plausible, with verification from European sources.
A Google search of "anasazi little ice age" leads to several confirming articles, but who knows the credentials of the authors?
  BDCA