Historical Adaptation to Climate Change in Japan: Integrating Palaeoclimatological Data and Archaeological Evidence

nakatsuka Takeshi Graduate School of Environmental Studies, Nagoya University

mitsutani Takumi Nara National Research Institute for Cultural Properties yasunari Tetsuzo Hydrospheric and Atmospheric Research Center, Nagoya University abe Osamu Graduate School of Environmental Studies, Nagoya University yasue Koh Faculty of Agriculture, Shinshu University ohyama Motonari Graduate School of Life Sciences, Tohoku University sakamoto Minoru National Museum of Japanese History kagawa Akira Forestry and Forest Product Research Institute akatsuka Jiro Center for Archeological Operation, Aichi Prefecture

How will climate change affect regional precipitation patterns? How ought human societies react to current changes of climate? This project takes a historical approach to such questions. Using high-resolution palaeoclimatological records, such as tree-ring oxygen isotope data, project researchers examine a number of regional signatures of climate variability during the past two millennia. Integrating such data with the extensive existing historical and archaeological evidence in and around the Japanese Archipelago will provide new insights into how past societies reacted to climate variability, and give clues as to how present and future societies can become tolerant of dynamic climate systems.

Research purpose

Society-climate relationships have been poorly understood, largely due to the lack of detailed palaeoclimate data. This project will therefore precisely reconstruct climate variability in several regions and historical periods in Japan. Historical and archaeological investigations will allow better understanding of the nature and characteristics of societies that are tolerant (or vulnerable) to climate changes. In integrating palaeoclimataological and historical data and synthesizing findings from several case studies, the objective of this project is to describe general social characteristics or modes associated with tolerance to environmental change.

Strength of the research method

Photo  Taking tree-ring samples from a live tree

High spatiotemporal resolution palaeoclimate data of tree-ring cellulose oxygen isotopic ratios plays the key role in this project. Recent technical developments allow accurate reconstruction of past climate variability in yearly or monthly timescales. Such high resolution datasets bring remarkable advantages. They allow correlation of specific palaeographic evidence with concrete climate events such as drought and flood. Specific climate events and cycles can also be accurately linked to human historical data in order to deepen understanding of past social vulnerabilities and changes.

Expected outcomes

Palaeoclimatalogical data obtained in this project will substantially improve understanding of Japanese history; it also will improve the validity of climate prediction models. Though there are different causes of past and current climate change, there may be similarities in how societies react to such change and an association between societies that are tolerant, or vulnerable, to local environmental changes and those that are tolerant or vulnerable to climate change. In this light, our analysis of climate-society relationships is expected to deepen our understanding of the capabilities of a human society to react to global environmental changes.

Figure

This figure describes past cycles (‘periodicity’) of summer rainfall variability in central Japan, which is derived from a tree-ring isotope data gained from an ancient buried tree sample. Periodicity (in years) is shown on the vertical axis. Colours indicate intensity of periodicity (long wavelenth colour = dominant periodicity). The figure therefore indicates that the dominant periodicity of summer rainfall variability changed significantly with time between 100 BC - 300 AD. The data allows us to hypothesize that multi-decadal variability affected historical events such as the period of ancient warfare in Wa (mid-late 2nd century AD) and subsequent appearance of the shaman Queen Himiko (late 2nd - mid 3rd century BC) of Yamataikoku, who was known for her rain-making rituals, and predictions of floods (cf. Records of Wei).