Abnormal Climate and Market Economy: The Impact of Solar Radiation on Rice Prices during the 1830s Famine in Japan

How do societies respond to varying climates? This query not only piques academic curiosity but also holds the key to how our society can adapt to the ongoing climate change. To shed light on this, we focus on the Tenpō Famine, a pivotal event in the 1830s that was one of the most severe famines due to poor harvests caused by an abnormal climate. By investigating such a significant occurrence, we aim to provide insights into vulnerable areas in the modern era. We chose the Tenpō Famine for the case study because it falls within a period for which analytical data are readily accessible (e.g., old diaries and price records). It occurred nationwide with regional differences, which makes it valuable for gaining a broad picture of the effects of climate variation. To understand the impact of climate change on societies in the past, it is necessary to consider social and economic information from such periods. This involves reconstructing spatial patterns of climate variation at a higher temporal resolution than provided by annual data. Japan has a wealth of historical diaries from 1821 to 1850.   Using these records, we developed a method to estimate solar radiation, enabling the successful reconstruction of historical solar radiation for all seasons at a higher temporal resolution than provided in annual data. Weather descriptions were categorised to estimate solar radiation, making possible analyses of climate variability and its effects at the monthly time scale. This represents a novel approach for analysing climate impacts on agriculture and the economy during this period. We then correlated the reconstructed solar radiation to rice prices, revealing a significant relationship between climatic anomalies and economic stability, particularly during the summer growing season. The results show that lower solar radiation, indicative of poor weather conditions, corresponded to higher rice prices, particularly during the summers of 1833 and 1836. The temporal resolution of economic data has also improved recently. Hence, this study contributes to understanding historical climatic impacts on society by providing an even more refined temporal resolution than was previously available. This underscores the need to integrate climate data into economic analyses to better understand the dynamics of societies facing environmental challenges. Our study is particularly relevant in the context of contemporary climate change and provides historical perspectives that can inform current policies and adaptation strategies.