[M-GI25] Holocene paleoenvironment, paleoclimate, and paleohazards in the Pacific Islands

[MGI25-P06] Project MOANA: Migration to remote Oceania reconsidered from Atmospheric and Aquatic environments

*Atsuko Yamazaki¹, Takuya Shimomaki², Ryohei Uchiyama³, Akira Goto⁴, Tomo Ishimura⁵, David Lecchini⁶, Tsuyoshi Watanabe⁷ (1.Graduate School of Environmental Studies, Nagoya University, 2.School of Science, Hokkaido University, 3.Graduate School of Science, Hokkaido University, 4.Nanzan University, 5.Tokyo National Research Institute for Cultural Properties, 6.Ecole Pratique des Hautes Etudes, 7.Research Institute for Humanity and Nature)

The remote islands of the Pacific Ocean are where humans arrived after spreading from Africa to the rest of the world. The history of human migration in the Pacific has been reconstructed through the footprints of the Lapita culture, which was created by the Lapita, a maritime people who were the first humans to be able to sail the distant seas. The Lapita culture emerged in the Bismarck Archipelago about 3,400 years ago and was distributed throughout Melanesia, including Fiji and New Caledonia, by 3,000 years ago. Later, their descendants, the ancient Polynesians, expanded into remote Oceania (Eastern Polynesia) between 1000 and 1200 AD. Why humans sailed back to the islands of remote Oceania, more than 2,000 km away, after 2,000 years of stagnation is one of the greatest mysteries in human history. The reasons for the eastward migration of ancient Polynesians could include an ideology that emphasized the importance of being the first ancestors in a new land, the development of navigation skills and canoes, and other cultural and technological backgrounds. The warm climate in Europe from the 950s to 1250s AD is called the Medieval Warm Period and has attracted attention as a background of Polynesian navigation. In recent years, however, the earth has not been uniformly warm during the Medieval Period, and cold or unstable temperature changes have been observed in various regions. Reef corals in the tropical and subtropical zones grow by accretion of carbonate skeletons with annual bands. Geochemical analysis along the growth direction can reconstruct the climate and marine environment over hundreds of years with a temporal resolution of weeks to months. This presentation will show the distribution of Holocene coral reefs in Bora Bora, French Polynesia, and the results of dating and geochemical analysis of fossil corals. We introduce the possibility of reconstructing the climate in the Medieval Period from the coral skeletons and that of directly comparison with the archaeological and technical background of the maritime voyages of the period.