Climate and War in China, noticed by George Zachar
Nature.com Published online: 13 July 2007
China had more wars in cold weather
Reduced agricultural productivity seems to trigger armed conflict.Between 1000 and 1911, there were 899 wars in eastern China, where most of the country's food is grown. Zhang's team classified each decade as a time of either very high (more than 30 wars), high (15-30 wars), or low (less than 15 wars) conflict.
Over the same period, climate data for the Northern Hemisphere show six major cycles of warm and cold phases. Crop and livestock production dropped significantly during the cold phases.
All four decades of very high conflict, and most periods of high conflict, coincided with cold phases, they found.