Rainfall variations in central Indo-Pacific over the past 2,700 y

Tropical rainfall variability is closely linked to meridional shifts of the Intertropical Convergence Zone (ITCZ) and zonal movements of the Walker circulation. The characteristics and mechanisms of tropical rainfall variations on centennial to decadal scales are, however, still unclear. Here, we re...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 116; no. 35; pp. 17201 - 17206
Main Authors Tan, Liangcheng, Shen, Chuan-Chou, Löwemark, Ludvig, Chawchai, Sakonvan, Edwards, R. Lawrence, Cai, Yanjun, Breitenbach, Sebastian F. M., Cheng, Hai, Chou, Yu-Chen, Duerrast, Helmut, Partin, Judson W., Cai, Wenju, Chabangborn, Akkaneewut, Gao, Yongli, Kwiecien, Ola, Wu, Chung-Che, Shi, Zhengguo, Hsu, Huang-Hsiung, Wohlfarth, Barbara
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences 27.08.2019
Subjects
20th century
Anthropogenic factors
central Indo-Pacific
Drying
El Nino
ENSO
Intertropical convergence zone
ITCZ
Physical Sciences
Rainfall
stalagmite
Tropical environments
Variability
ITCZ
stalagmite
rainfall
central Indo-Pacific
ENSO
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Summary:Tropical rainfall variability is closely linked to meridional shifts of the Intertropical Convergence Zone (ITCZ) and zonal movements of the Walker circulation. The characteristics and mechanisms of tropical rainfall variations on centennial to decadal scales are, however, still unclear. Here, we reconstruct a replicated stalagmite-based 2,700-y-long, continuous record of rainfall for the deeply convective northern central Indo-Pacific (NCIP) region. Our record reveals decreasing rainfall in the NCIP over the past 2,700 y, similar to other records from the northern tropics. Notable centennial- to decadal-scale dry climate episodes occurred in both the NCIP and the southern central Indo-Pacific (SCIP) during the 20th century [Current Warm Period (CWP)] and the Medieval Warm Period (MWP), resembling enhanced El Niño-like conditions. Further, we developed a 2,000-y-long ITCZ shift index record that supports an overall southward ITCZ shift in the central Indo-Pacific and indicates southward mean ITCZ positions during the earlyMWP and the CWP. As a result, the drying trend since the 20th century in the northern tropics is similar to that observed during the past warm period, suggesting that a possible anthropogenic forcing of rainfall remains indistinguishable from natural variability.
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Author contributions: L.T., C.-C.S., and B.W. designed research; L.T., L.L., S.C., Y.-C.C., H.D., A.C., Z.S., and H.-H.H. performed research; L.T., C.-C.S., L.L., S.C., R.L.E., Y.C., S.F.M.B., H.C., J.W.P., W.C., Y.G., C.-C.W., Z.S., and B.W. analyzed data; and L.T., C.-C.S., Y.C., S.F.M.B., H.C., J.W.P., and O.K. wrote the paper.
Edited by Raymond Bradley, Department of Geosciences, University of Massachusetts, and accepted by Editorial Board Member Jean Jouzel July 13, 2019 (received for review February 22, 2019)
ISSN:0027-8424
1091-6490
1091-6490
DOI:10.1073/pnas.1903167116