Rainfall variations in central Indo-Pacific over the past 2,700 y
| Autor: | Chuan-Chou Shen, Ola Kwiecien, Helmut Duerrast, Yu Chen Chou, Yanjun Cai, Barbara Wohlfarth, Akkaneewut Chabangborn, Judson W. Partin, Wenju Cai, Sakonvan Chawchai, Ludvig Löwemark, Hai Cheng, Chung-Che Wu, R. Lawrence Edwards, Liangcheng Tan, Huang Hsiung Hsu, Zhengguo Shi, Yongli Gao, Sebastian F. M. Breitenbach |
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| Rok vydání: | 2019 |
| Předmět: |
010504 meteorology & atmospheric sciences
rainfall F700 F800 Stalagmite Forcing (mathematics) F600 010502 geochemistry & geophysics 01 natural sciences Earth Atmospheric and Planetary Sciences Centennial central Indo-Pacific stalagmite ITCZ 0105 earth and related environmental sciences geography Multidisciplinary geography.geographical_feature_category Intertropical Convergence Zone Tropics 13. Climate action Climatology Physical Sciences Period (geology) Walker circulation ENSO Geology Indo-Pacific |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.1903167116 |
| Popis: | Significance We present a high-resolution, replicated speleothem δ18O record from Klang Cave in southern Thailand that characterizes rainfall variation in NCIP over the past 2,700 y. This record reveals notable dry climate conditions during the current and past warm periods, similar to the observations in SCIP, which resemble enhanced El Niño-like conditions. Using a newly developed ITCZ shift index, we find a southward shifted ITCZ during the early MWP and the CWP. Our results suggest that detecting changes in rainfall due to anthropogenic forcing still remains indistinguishable from natural variability in the northern tropics. 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 early MWP 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. |
| Databáze: | OpenAIRE |
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