Geographer David Zhang of the University of Hong Kong, and colleagues, just published a new study in Proceedings of the National Academy of Sciences that links climate fluctuations to darker historical periods in human history.
Using a statistical analysis tool that contained socioeconomic, ecological, demographic, and other data, Zhang used the Granger causality analysis to compare 14 variables such as human height, the price of gold, tree’s ring width, and temperatures in Europe from 1500 to 1800, to determine whether any cause and effect relationships existed. After dividing time periods by 40 to 150 years, the researchers used data from paleoclimatology to ascertain what major events during this time were caused by temperature shifts.
Their results showed that “climate shifts were a statistically significant cause of social disturbance, war, migration, epidemics, famine, and nutritional status.” Not surprisingly, the biggest influence was through agriculture. Zhang explains that “[a] falling supply of crops will drive up the price of gold and cause inflation. Similarly, epidemics can be exacerbated by famine. And when people are miserable, they are likely to become angry with their governments and each other, resulting in war.”
This temperature mapping also allowed the researchers to analyze historical correlations and correctly predict when past crises occurred.
While Zhang’s work is being praised for its plethora of data, some scientists feel the research falls short of its potential. Halvard Buhaug of Peace Research Institute Oslo states, it’s “unclear whether this research is relevant for the present day, when humans are facing a period of rapid temperature changes.”