[M-ZZ43] Transdisciplinary Network linking Space-Earth Environmental Science with History and Archaeology

[MZZ43-03] Tree-ring oxygen isotope dating and climate reconstruction

★Invited Papers

*Masaki Sano¹, Kaoru kamatani² (1.National Museum of Japanese History, 2.Ritsumeikan University)

Keywords:dendrochronology, oxygen isotope, climate reconstruction, historical document, rice yield

In Japan, although a master chronology based on ring widths over the past 3,000 years has already been developed, there are significant limitations on the species and number of annual rings to be dated. On the other hand, tree-ring oxygen isotope ratios are controlled by simple climatic factors and are less dependent on tree species. This report outlines tree-ring oxygen isotope chronologies that have been developed in Japan over the past 5,000 years, and provides examples of how these chronologies have been used to date archaeological timbers. Furthermore, tree-ring oxygen isotope ratios are mainly controlled by relative humidity and oxygen isotope of precipitation during the summer season, making it possible to reconstruct past hydroclimate at annual resolution. We present recent progress in isotope dendroclimatology in Asia. Then we show the potential for environmental history research by comparing paleoclimatic data with historical records. Specifically, the effect of climate change on rice yield was evaluated by estimating paddy rice production based on historical documents. We were able to demonstrate that rice yield, reconstructed from tax exemptions collected from villages along the shores of Lake Biwa in the early modern period, decreased in flood years through quantitative comparison with the reconstructed precipitation based on tree rings. In addition, we were able to observe a social response to climate change, as dredging of the Seta River, the outflow river of Lake Biwa, has been conducted in order to escape the chronic submergence of rice fields due to repeated flooding.