[MGI41-03] Interactive data production and data analysis on past climate between paleoclimatology, history and archaeology for last 3,000 years in Japan
Keywords:paleoclimatology, history, archaeology, dendrochronology, oxygen isotope ratio, climate variation
We have experienced sequentially 5 phases in the interactive data production and data analyses between different disciplines. Phase-1 is the introduction of a new paleoclimate proxy (tree-ring cellulose δ18O) as a basis of the project. It can be utilized to reconstruct summer hydroclimate critical for rice paddy cultivation, main livelihood of Japanese people for last 3,000 years, and important for historical and archaeological studies. Phase-2 is the collaborative multi-millennial extension of tree-ring δ18O chronologies over Japan. Archaeologists provided paleoclimatologists of numerous excavated wood in order to extend the chronology because it can be used to date newly excavated woods reversely. Phase-3 is the development of a method reconstructing long-term climate variations. The tree-ring δ18O chronologies are influenced by serious age effects, so that paleoclimatologists must have invented a new method to reconstruct past climate seamlessly from annual to millennial scales corresponding to requests from historians and archaeologists (Nakatsuka et al., 2020; https://doi.org/10.5194/cp-2020-6). Phase-4 is the validation and utilization of the paleoclimate data beyond disciplines. The climate data are informative for historians and archaeologists so that they could verify and utilize the data by comparison with numerous evidences in Japanese history. Phase-5 is the discovery of a new climate-history relationship. High correlations between the tree-ring δ18O and agricultural productivities enable us to investigate impacts of climate variation to Japanese (Chinese) history at various time scales and we found that intermittent enhancements of multi-decadal climate variability often induced societal upheavals and political regime shifts in East Asian long history.
Interactive data production and data analyses on past climate between paleoclimatology, history and archaeology have brought great progresses to each discipline. However, there were also tiny but significant problems in the collaboration. First, it usually takes a very long time, more than several years, for paleoclimatologists to construct and verify the multi-millennial annually-resolved paleoclimate data in collaboration with historians and archaeologists. Second, historians and archaeologists in Japan usually write papers alone without co-authors even if they use a new paleoclimatological data. Both of the two problems reduce the motivation of young paleoclimatologists and damage the inter-disciplinary collaboration. In order to mitigate negative influences of these problems, paleoclimatologists, historians and archaeologists should share a common research target such as solution of global environmental issues by intense mutual discussions.