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A high-resolution speleothem record of western equatorial Pacific rainfall: Implications for Holocene ENSO evolution

Chen, Sang and Hoffmann, Sharon S. and Lund, David C. and Cobb, Kim M. and Emile-Geay, Julien and Adkins, Jess F. (2016) A high-resolution speleothem record of western equatorial Pacific rainfall: Implications for Holocene ENSO evolution. Earth and Planetary Science Letters, 442 . pp. 61-71. ISSN 0012-821X. https://resolver.caltech.edu/CaltechAUTHORS:20160527-130608031

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Abstract

The El Niño-Southern Oscillation (ENSO) is the primary driver of interannual climate variability in the tropics and subtropics. Despite substantial progress in understanding ocean–atmosphere feedbacks that drive ENSO today, relatively little is known about its behavior on centennial and longer timescales. Paleoclimate records from lakes, corals, molluscs and deep-sea sediments generally suggest that ENSO variability was weaker during the mid-Holocene (4–6 kyr BP) than the late Holocene (0–4 kyr BP). However, discrepancies amongst the records preclude a clear timeline of Holocene ENSO evolution and therefore the attribution of ENSO variability to specific climate forcing mechanisms. Here we present δ^(18)O results from a U–Th dated speleothem in Malaysian Borneo sampled at sub-annual resolution. The δ^(18)O of Borneo rainfall is a robust proxy of regional convective intensity and precipitation amount, both of which are directly influenced by ENSO activity. Our estimates of stalagmite δ^(18)O variance at ENSO periods (2–7 yr) show a significant reduction in interannual variability during the mid-Holocene (3240–3380 and 5160–5230 yr BP) relative to both the late Holocene (2390–2590 yr BP) and early Holocene (6590–6730 yr BP). The Borneo results are therefore inconsistent with lacustrine records of ENSO from the eastern equatorial Pacific that show little or no ENSO variance during the early Holocene. Instead, our results support coral, mollusc and foraminiferal records from the central and eastern equatorial Pacific that show a mid-Holocene minimum in ENSO variance. Reduced mid-Holocene interannual δ^(18)O variability in Borneo coincides with an overall minimum in mean δ^(18)O from 3.5 to 5.5 kyr BP. Persistent warm pool convection would tend to enhance the Walker circulation during the mid-Holocene, which likely contributed to reduced ENSO variance during this period. This finding implies that both convective intensity and interannual variability in Borneo are driven by coupled air-sea dynamics that are sensitive to precessional insolation forcing. Isolating the exact mechanisms that drive long-term ENSO evolution will require additional high-resolution paleoclimatic reconstructions and further investigation of Holocene tropical climate evolution using coupled climate models.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.epsl.2016.02.050DOIArticle
http://www.sciencedirect.com/science/article/pii/S0012821X16300759PublisherArticle
ORCID:
AuthorORCID
Chen, Sang0000-0001-8941-0791
Lund, David C.0000-0002-4847-2889
Adkins, Jess F.0000-0002-3174-5190
Additional Information:© 2016 Elsevier B.V. Received 29 October 2015; Received in revised form 23 February 2016; Accepted 28 February 2016; Available online 10 March 2016. We would like to thank Gunung Buda and Gunung Mulu National Park crew for field assistance. We are grateful to Lora Wingate who performed the stable isotope analyses. We would also like to thank Rachel Sortor, Rachel Franzblau, Rachel Seltz, Alec Washabaugh and Naomi Huntley for help with micromilling, and Stacy Carolin for help with the U–Th dating. Derek Vance, Kathleen Johnson and an anonymous reviewer provided constructive feedbacks that helped improve the manuscript. The research was supported by NSF grant AGS-1103385.
Funders:
Funding AgencyGrant Number
NSFAGS-1103385
Subject Keywords:ENSO; Borneo; speleothem δ18O; western Pacific rainfall; Holocene
Record Number:CaltechAUTHORS:20160527-130608031
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160527-130608031
Official Citation:Sang Chen, Sharon S. Hoffmann, David C. Lund, Kim M. Cobb, Julien Emile-Geay, Jess F. Adkins, A high-resolution speleothem record of western equatorial Pacific rainfall: Implications for Holocene ENSO evolution, Earth and Planetary Science Letters, Volume 442, 15 May 2016, Pages 61-71, ISSN 0012-821X, http://dx.doi.org/10.1016/j.epsl.2016.02.050. (http://www.sciencedirect.com/science/article/pii/S0012821X16300759)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67462
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:27 May 2016 20:17
Last Modified:09 Mar 2020 13:19

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