Why Were There No Severe Famines in Fourteenth-Century Japan? Social Change, Resilience, and Climatic Cooling

Climate history is of interest for what it can tell us about how changes in temperature and precipitation affected societies in the past and for the hints it may provide regarding what makes societies vulnerable or resilient to such changes or, by extension, other external shocks. In the present article I focus on climate change in medieval Japan in an attempt to elucidate the relationship between changes in temperature and precipitation, on the one hand, and the occurrence of famine, on the other.¹

Medieval Japan was a predominantly agricultural society whose institutions and technologies were fine-tuned to fit prevailing climatic conditions; as a result, in some cases fluctuations in temperature and precipitation had huge effects on social conditions. For example, there was a sharp decrease in temperature and an increase in precipitation starting in the thirteenth century. As one might expect, cold summers typically led to poor harvests, which led to shortages in the food supply and ultimately to famine. Oddly, however, for about a century starting in 1280, Japan experienced similar climatic conditions, including ongoing cooling, and yet was not beleaguered by famine. The purpose of this article is to explain what made fourteenth-century Japanese society relatively resilient to extreme weather events.

To put my conclusion first, the absence of severe famines in this period was not the result of direct adaptations or responses to inclement weather per se, but rather the result of what we might call fortuitous pre-adaptation, specifically changes in the commercial economy during the late thirteenth century that enabled the redistribution of rice from areas where food was more available to those areas where it was more scarce. The analysis leading to this conclusion is based on systematic quantitative comparisons of medieval historical records with paleoclimatic data. Research of this kind has recently become possible owing to greater accessibility of historical records and to wholly new advances in paleoclimatology.

Over the past several decades, medieval historical records have become more available to researchers. A major landmark was the compilation and publication of Kamakura ibun 鎌倉遺文 (Extant Documents from the Kamakura Period; 1971–1997) under the editorship of Takeuchi Rizō 竹内理三. Over a period of twenty years, Takeuchi amassed a total of over 36,000 documents spanning 1185 to 1334.² Including supplements and indexes the Kamakura ibun series currently comprises fifty-five volumes, and the publication of temple documents from Tōji 東寺 is presently under way. This groundbreaking compendium of historical materials has greatly advanced the field of early medieval studies, and scholars have increasingly come to see not only the qualitative but also the quantitative potential of document collections. A CD-ROM version of Kamakura ibun was published in 2008, providing even easier access to historical data and offering a full search function that has led to a proliferation of numeric and statistical analyses.³ With regard to the focus of the present study—extreme weather events and agricultural disasters—another indispensable reference is Nihon chūsei kishō saigaishi nenpyō kō 日本中世気象災害史 年表稿 (Chronology of Weather Disaster History in Medieval Japan), compiled by Fujiki Hisashi 藤木久志 in 2007.⁴ This collection lists chronologically more than 14,000 medieval Japanese documents related to natural disasters, insect damage (such as that caused by locusts), poor harvests, famine, and epidemics. Although limited to previously transcribed and published sources, the comprehensive nature of Fujiki’s work makes it possible to accurately discern broad social trends.

Perhaps even more dramatic have been scientific advances in paleoclimatology. Until recently, those interested in climate change in Japanese history typically relied on scattered historical records, for example diary entries indicating when cherry trees bloomed in Kyoto or when Lake Suwa 諏訪 froze over in winter. Scientific techniques focusing on the changing frequency of different types of fossil pollen or on the changing width or chemical composition of tree rings were also employed, but the results were rather crude. In the last several years, however, the analysis of tree rings has made huge strides, and researchers are now benefiting from the availability of essentially...