Borneo peat coring; reconstruction of tropical atmospheric convection activity during the llast 4000 years

2017 Fiscal Year Final Research Report

• Project/Area Number: 15H05210
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 海外学術
• Research Field: Geology
• Research Institution: Hokkaido University
• Principal Investigator: YAMAMOTO Masanobu 北海道大学, 地球環境科学研究院, 准教授 (60332475)
• Co-Investigator(Kenkyū-buntansha): 関 宰 北海道大学, 低温科学研究所, 准教授 (30374648) ; 林 竜馬 滋賀県立琵琶湖博物館, 研究部, 学芸員 (60636067)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: ボルネオ / 完新世 / 泥炭 / 乾湿変動 / エルニーニョ / 微粒炭 / 野火 / 太陽放射量

Outline of Final Research Achievements

We generated a 6000-year long charcoal record from three different sites in northwestern Borneo that shows large fluctuation in charcoal abundance. Two different sites at 460 km distance show common abundance peaks, suggesting that climate change regulated wild fire frequency. The abundance peak appeared every several hundred years, showing a 560-year periodicity. The peaks correspond well to those of solar irradiance and the frequency of El Nino-induced flooding in an Ecuadorian lake from 4000 to 1000 year BP, but the correspondence is not significant and even reverse in other periods. There is no clear correspondence with the East Asian summer and winter monsoon records. We suggest that multi-centennial scale changes in the frequency of El Nino was a factor controlling precipitation in northwestern Borneo and the frequency of wildfires in the peatlands.

Free Research Field

古気候学