# Unusual solar radiation and its impact on the Japanese rice market during the 1830s famine

## TL;DR

This study explores how unusual solar radiation in the 1830s led to a rice market crisis in Japan, showing the link between climate and economic instability.

## Contribution

A novel reconstruction of solar radiation from historical diaries to analyze its impact on rice prices during the Tenpō Famine.

## Key findings

- Reduced solar radiation in 1836 led to rice prices rising to three to four times the normal level.
- Cold conditions and low solar radiation in July and August 1836 persisted for three months, worsening the famine.
- Principal component analysis revealed spatiotemporal patterns linking climate anomalies to market price fluctuations.

## Abstract

We investigated the interplay between climatic anomalies and economic fluctuations in early modern Japan (1603 − 1867), focusing on the Tenpō Famine of the 1830s. Specifically, we reconstructed solar radiation from 1821 to 1850 using descriptions from 18 historical diaries. This represents a novel approach to analyzing climatic impacts on agriculture and the economy during this period. The results suggest that reduced solar radiation, indicative of poor weather conditions, was followed by a substantial increase in rice prices, which rose to three to four times the normal level (from 50-70 to around 200). This rise occurred particularly during the summer of 1836, when solar radiation in July and August was approximately 10% below normal, and cold conditions persisted for three months. Applying principal component analysis to the reconstructed solar radiation data revealed spatiotemporal patterns that elucidated the link between climatic anomalies and their impacts on market prices during the Tenpō Famine. This indicates the sensitivity of market prices and economic stability to climate fluctuations. Using monthly rather than annual data, this study offers further evidence for the connections between climate, agriculture, and economic fluctuations. Our findings provide historical perspectives that could contribute to broader considerations in climate adaptation and policymaking. Additionally, this study suggests further research directions and encourages continued exploration of the relationship among climate change, agriculture, and economic fluctuations, inspiring future research in this field.