古代の貝殻データが3,000年にわたる台風パターンの変化を解明(Ancient Shell Data Reveals Shifts in Tropical Cyclone Patterns Over 3,000 Years)

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2025-07-02 中国科学院(CAS)

中国科学院地球環境研究所の研究チームは、約3000年前の巨大二枚貝「トリダクナ」の化石から得た12年間の成長記録を用いて、熱帯低気圧(TC)の活動変化を日単位で解析可能な初の代替指標データセットを構築した。南シナ海北部で発掘されたこの貝殻の分析により、当時のTCは現在より約15%多く、発生ピークは秋ではなく夏だったことが判明。これは、赤道収束帯(ITCZ)の北上による季節的な気候変動と関連し、TCの季節的変動の背後にあるメカニズム解明に貢献する画期的成果とされる。

<関連情報>

南シナ海における熱帯低気圧季節の先史時代的シフト:シャコガイ貝殻の日分解能記録からの証拠 Prehistoric shifts in tropical cyclone season in the South China sea: evidence from daily resolution records of giant clam shells

Nanyu Zhao,Hong Yan,Ge Shi,Fan Luo,Tao Han,Chengcheng Liu & John Dodson
npj Climate and Atmospheric Science  Published:14 June 2025
DOI:https://doi.org/10.1038/s41612-025-01100-1

古代の貝殻データが3,000年にわたる台風パターンの変化を解明(Ancient Shell Data Reveals Shifts in Tropical Cyclone Patterns Over 3,000 Years)

Abstract

The impact of climate change on tropical cyclones (TCs) remains a critical concern, but understanding is limited by short instrumental records and low-resolution prehistoric data. Here, we present the first daily-resolution proxy data for investigating prehistoric TC activity, using a 12-year growth rate record of a fossil Tridacna shell (circa 3 ka BP) from the northern South China Sea (NSCS). By analyzing temporal patterns in the proxy data, we derived monthly TC frequency estimates. While modern TC frequency in the NSCS peaks in autumn (September–October), our results showed that TCs at 3 ka BP occurred more frequently in summer (June–July–August), with approximately 15% higher frequency than present. Combined with paleoclimate records, we suggested that this seasonal shift and increased frequency were likely linked to the relatively northward migration of the Intertropical Convergence Zone, which provided favourable conditions for TC formation and development. Our findings imply that future warming would contribute to earlier TC seasons and increased TC frequency in the NSCS.

1702地球物理及び地球化学
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