Maunder Minimum
The General Crisis overlaps fairly neatly with the Little Ice Age whose peak some authorities locate in the 17th century. Of particular interest is the overlap with the Maunder Minimum, El Niño events and an abnormal spate of volcanic activity. Climatologists such as David Rind and Jonathan Overpeck have hypothesised that these three events are interlinked. Across the Northern Hemisphere, the mid-17th century experienced almost unprecedented death rates. Geoffrey Parker has suggested that environmental factors may have been in part to blame, especially the global cooling trend of this period. David D. Zhang et al provide a detailed analysis here.