Ancient history sheds new light on connection between weather and war

Data extracted from the oldest surviving document recording Korean history shows a strong correlation between extreme weather events and war.

The research, which was recently published as a study in the Proceedings of the National Academy of Sciences (PNAS), shows the three states that ruled over the Korean Peninsula from 18 BCE to 660 CE were more than twice as likely to be involved in an armed conflict with a neighbor when also experiencing a weather shock such as drought or excessive rainfall.

For the study, Santa Fe Institute External Professor Rajiv Sethi (Barnard College, Columbia University) and co-author Tackseung Jun of Kyung Hee University in South Korea analyzed data extracted from detailed accounts of conflicts and extreme weather events contained in the Samguk Sagi, or History of the Three Kingdoms.

Originally commissioned by King Injong of Goryeo in the 12th century, the Samguk Sagi provides scientists access to rare historical data involving a set of stable political entities for which both weather and conflict events were recorded over several centuries.

Their analysis revealed shocks were far more likely to result in a state's invasion than for one to go on the offensive.

Additionally, they identified food insecurity as a critical source of vulnerability to invasion.

The researchers' work sheds new light on the relationship between climate change and war. It could ultimately help with efforts to identify and protect people living in the world today that are particularly vulnerable to climate-related conflict.

"Extreme weather events and military conflict over seven centuries in ancient Korea" is published in PNAS.