Changes in climate and secular population cycles in China, 1000 CE to 1911

Abstract

Many studies of secular population cycles in historical China conclude that when population is large - relative to the land's carrying capacity - further population increase can lead to mortality crises through war, famine and epidemics, resulting in subsequent population decline. In these studies, population cycles are thought to be driven primarily by population growth. Nevertheless, some scholars have noted a strong correlation between deteriorating climate, dynastic change, and population collapse in historical China. They suggest climate forcing as the underlying driver of population cycles, but quantitative evidence has been lacking to date. In the present study, we employed high resolution temperature data, reports on mortality events, and population datasets to quantitatively examine the extent to which climate change was responsible for Chinese population cycles. Results show that there were 5 major population contractions in China between 1000 CE and 1911, and all of them occurred in periods with a cold climate, when mortality crises triggered population collapses. Nevertheless, the climate-population association is non-linear, because it is mediated by population pressure. Although social buffers were increasingly effective in dissipating climate forcing, they could not prevent population collapses from occurring during periods of long-term cooling. Our results challenge classic Malthusian and post-Malthusian interpretations of historical Chinese population cycles.© Inter-Research 2010.