Climatic Change, Wars and Dynastic Cycles in China Over the Last Millennium

Abstract

In recent years, the phenomenon of global warming and its implications for the future of the human race have been intensively studied. In contrast, few quantitative studies have been attempted on the notable effects of past climatic changes upon human societies. This study explored the relationship between climatic change and war in China by comparing high-resolution paleoclimatic reconstructions with known war incidences in China in the last millennium. War frequencies showed a cyclic pattern that closely followed the global paleo-temperature changes. Strong and significant correlations were found between climatic change, war occurrence, harvest level, population size and dynastic transition. During cold phases, China suffered more often from frequent wars, population decline and dynastic changes. The quantitative analyses suggested that the reduction of thermal energy input during a cold phase would lower the land carrying capacity in the traditional agrarian society, and the population size, with significant accretions accrued in the previous warm phase, could not be sustained by the shrinking resource base. The stressed human-nature relationship generated a 'push force', leading to more frequent wars between states, regions and tribes, which could lead to the collapse of dynasties and collapses of human population size. War frequencies varied according to geographical locations (North, Central and South China) due to spatial variations in the physical environment and hence differential response to climatic change. Moreover, war occurrences demonstrated an obvious time lag after an episode of temperature fall, and the three geographical regions experienced different length of time lags. This research also shows that human population increases and collapses were correlated with the climatic phases and the social instabilities that were induced by climate changes during the last millennium. The findings proposed a new interpretation of human-nature relationship in the past, with implications for the impacts of anomalous global warming on future human conflicts.

The causality analysis of climate change and large-scale human crisis

“…More recent breakthroughs came from research adopting quantitative approaches to all known cases of social crisis. These studies show that, in recent history, climate change was responsible for the outbreak of war, dynastic transition, and population decline in China, Europe, and around the world because of climate-induced shrinkage of agricultural production (6)(7)(8)(9)(10)(11)(12)(13)(14)(15). However, the underlying causal linkages from climate change to agricultural production and various human catastrophes in history have not been addressed scientifically.…”

Climate, conflict, and social stability: what does the evidence say?

“…Jamestown Colony, settled nearby two decades later, almost collapsed during a similar drought. Zhang et al (2006) examine Chinese records from 1000-1911 and find cold periods of 10-100 years were associated with higher frequencies of war, rebellion, population decline and all five dynastic transitions. Zhang et al argue that in temperate China, cold temperatures reduced yields, triggering civil unrest and political instability.…”

A preliminary analysis of economic fluctuations and climate changes in China from BC 220 to AD 1910

“…Moreover, previous work has shown that low temperatures are also correlated with belowaverage population growth in China over the past millennia (Lee et al 2008). Decreasing food yields induced by a deteriorating climate was unable to support surplus population growth during the warm periods (Lee et al 2008;Zhang et al 2006). Moreover, sustainable economic development became more susceptible to disturbances from social unrest and war , particularly considering that regional climate changes would produce different effects on the Sino society and nomadic society (Fang and Liu 1992).…”

“…Using long-term historical records to reconstruct a socioeconomic proxy and to quantitatively study the relationship between climate change and historical rhythms has been an advantage in China for climate sociology research (Fang et al 2013;Ye et al 2012;Su et al 2014;Zhang et al 2006;Lee et al 2008). Previous studies paid more attention to the climatic effects on historical cyclical rhythms based on population (Lee et al 2008), the frequency of revolts and wars (Zhang et al 2010c;Zhang et al 2006) and dynastic collapse events .…”

“…Previous studies paid more attention to the climatic effects on historical cyclical rhythms based on population (Lee et al 2008), the frequency of revolts and wars (Zhang et al 2010c;Zhang et al 2006) and dynastic collapse events . In comparison, climatic effects on the macroeconomy have received little attention due to a lack of continuous and comparable statistical economic data.…”