[U-11] Climate change during the Quaternary and Anthropocene

10:45 AM - 11:00 AM JST(1:45 AM - 2:00 AM UTC)

[U11-06] High-resolution climate change from the Late-glacial to early Holocene transition reconstructed from stalagmite, Shiga, Japan, and implications for human history★Invited Papers

*Nodoka Kuramoto¹, Masayuki Ikeda¹, Akihiro Kano¹, Chuan-Chou Shen², Chun-Yuan Huang², Aki Sakuma¹, Yuji Abe³ (1.The University of Tokyo, 2.National Taiwan University, 3.Taga Town Museum)

Keywords:

stalagmite,deglacial period,oxygen stable isotope,U-Th dating,paleoclimate reconstruction,Jōmon period

The Last Glacial-Interglacial Transition (LGIT; 16-8 ka) is characterized by prominent global climate changes. This period is also a pivotal turning point in human history marked by the emergence of agriculture and cultivation. To elucidate the mechanisms of climate change and its impact on humanity, high-resolution proxy records from mid-latitude areas are required. It has been proposed that about 15,000 years ago, the Late glacial interstadial (equivalent to GI-1/Bølling-Allerød) started ca. two centuries earlier in East Asia than in the North Atlantic based on the pollen-based paleotemperature reconstruction from the annually-laminated Lake Suigetsu sediment (Nakagawa et al., 2021). This pollen data also suggested that 11,000 years ago, when agriculture first began in the West Asian region, the climate was stable (Nakagawa et al., 2021). However, this temperature reconstruction is based on the assumption that pollen assemblages respond linearly to temperature change. To verify the reconstructed temperature, another geological record which is independent of biological responses is needed. Here we present the high-resolution oxygen isotope (δ¹⁸O) record that covers the LGIT from U-Th dated stalagmite, KK-2, from Kawachi-no-kaza-ana Cave in Shiga Prefecture, 50 km southeast of Lake Suigetsu. Precise U-Th dating with a 2-sigma uncertainty of less than ±1% was obtained at the High-precision mass spectrometry and environment change laboratory (HISPEC), National Taiwan University. Approximately decadal resolution of the δ¹⁸O record generally shows a similar trend to pollen-based temperature reconstructions from Lake Suigetsu. On the other hand, the δ¹⁸O record decreases around 13 ka and 11 ka, when settlement and plant cultivation started in Jōmon period, Japan. This suggests that a warm and humid climate state may have been more important for human society than the climatic stability.