By looking at temperature fluctuations and reduced agricultural production in eastern China's past, David Zhang from the University of Hong Kong and his colleagues say they can predict the geopolitics of global warming's future.

They found that warfare frequency in eastern China, and the southern part in particular, significantly correlated with temperature oscillations. Almost all peaks of warfare and dynastic changes coincided with cold phases.

Looking to the future and applying their findings, Zhang and colleagues suggest that shortages of essential resources, such as fresh water, agricultural land, energy sources and minerals may trigger more armed conflicts among human societies.

Zhang and his team looked at the impact of climate change on warfare frequency over the last millennium in eastern China. The agricultural production in the region supports the majority of the Chinese population. The authors reviewed warfare data from 899 wars in eastern China between 1000 and 1911, documented in the Tabulation of Wars in Ancient China. They cross-referenced these data with Northern Hemispheric climate series temperature data for the same period.

Temperature fluctuations directly impact agriculture and horticulture and, in societies with limited technology such as pre-industrial China, cooling temperatures hugely impact the availability of crops and herds. In times of such ecological stress, warfare could be the ultimate means of redistributing resources, according to Zhang and his team.

The authors conclude that “it was the oscillations of agricultural production brought by long-term climate change that drove China’s historical war-peace cycles.” They recommend that researchers consider climate change part of the equation when they consider the reasons behind wars in our history.

Zhang DD, Zhang J, Lee HF, He Y (2007). "Climate change and war frequency in eastern China over the last millennium", Human Ecology; (DOI 10.1007/s10745-007-9115-8)