[M-IS04] Evolution and variability of the Asian Monsoon and Indo-Pacific climate during the Cenozoic Era

[MIS04-P01] Tropical Western Pacific hydrology during the last 6,000 years based on wildfire charcoal records from Borneo

*山本 正伸¹、菊地 隼史¹、櫻井 弘道¹、林 竜馬²、関 宰³、大森 貴之⁴、スライマン アブドラ⁵、シャリ ハスリザル⁶、アブドラ モド ズルヒルミ⁷、メリング ルリー⁷ (1.北海道大学大学院地球環境科学研究院、2.琵琶湖博物館、3.北海道大学低温科学研究所、4.東京大学総合研究博物館、5.マレーシア鉱物地球科学局、6.マレーシアトレンガヌ大学、7.サラワク熱帯泥炭研究所)

キーワード：炭、過去の火災、ボルネオ、完新世、降雨、太陽強制

The forcing of multi-centennial climate variability in the Western Pacific Warm Pool (WPWP) region is not fully understood. Here we generated 6-ky long continuous charcoal records from five peatlands in Borneo. Peaks of charcoal abundance every several hundred years were identified at each site, indicating that the peatlands repeatedly experienced aridity and wildfires. Major fire events were identified at ~5.2, 4.7, 4.3, 3.7, 3.1, 2.5, 2.2, 1.6, 1.1, 0.6 and 0.2 ka. Most of these coincided with the maxima of Borneo speleothem δ¹⁸O, and occurred in the high solar activity periods soon after the solar minima. This suggests that the solar minima increased rainfall, leading to fuel accumulation, while the subsequent higher solar activity decreased rainfall, increasing aridity and wildfire frequency. This result challenges the hypothesis that high solar activity intensifies atmospheric convection in the WPWP area.