DOI: 10.25921/vd61-pw29
title: NOAA/WDS Paleoclimatology - Partin et al. 2007 Northern Borneo Stalagmite Oxygen Isotope Data

description: Models and palaeoclimate data suggest that the tropical Pacific climate system plays a key part in the mechanisms underlying orbital-scale and abrupt climate change. Atmospheric convection over the western tropical Pacific is a major source of heat and moisture to extratropical regions, and may therefore influence the global climate response to a variety of forcing factors. The response of tropical Pacific convection to changes in global climate boundary conditions, abrupt climate changes and radiative forcing remains uncertain, however. Here we present three absolutely-dated oxygen isotope records from stalagmites in northern Borneo that reflect changes in west Pacific warm pool hydrology over the past 27,000 years. Our results suggest that convection over the western tropical Pacific weakened 18,000-20,000 years ago, as tropical Pacific and Antarctic temperatures began to rise during the early stages of deglaciation. Convective activity, as inferred from oxygen isotopes, reached a minimum during Heinrich event 1, when the Atlantic meridional overturning circulation was weak, pointing to feedbacks between the strength of the overturning circulation and tropical Pacific hydrology. There is no evidence of the Younger Dryas event in the stalagmite records, however, suggesting that different mechanisms operated during these two abrupt deglacial climate events. During the Holocene epoch, convective activity appears to track changes in spring and autumn insolation, highlighting the sensitivity of tropical Pacific convection to external radiative forcing. Together, these findings demonstrate that the tropical Pacific hydrological cycle is sensitive to high-latitude climate processes in both hemispheres, as well as to external radiative forcing, and that it may have a central role in abrupt climate change events.
description: Three stalagmite d18O records from Gunung Buda National Park, Northern Borneo, Malaysia (4º02'N, 114º48'E, elev. 150m), for the last 27ka. Samples SSC01 and SCH02 originate from Snail Shell Cave and formed ~250m from the cave entrance and ~20m from each other.  Sample BA04 formed >500m from the cave entrance in Bukit Assam Cave, which lies ~6km NNE from Snail Shell Cave. 

The age model for each record is comprised of 24-26 U/Th Dates corrected using stalagmite specific 230Th/232Th (Suppl. Info in Partin et al., 2007; Adkins et al., 2007); breaks in the record are dated hiatuses. The average temporal resolution for each d18O record is 72, 56, and 60 yrs/sample for SCH02, SSC01, and BA04, respectively.  Rules for establishing the age models from U/Th dates, as well as known hiatuses, are provided below.  A "master d18O record" is constructed by splicing together portions of the three individual records. The master record is best used with error bars calculated from overlapping portions of all three stalagmites. For all records, d18O data are reported with respect to PDB, and ages are reported as years before present. Two rules were used for establishing the final age model: 1) For ages older than 11,000 years, individual age errors for a U-series point must be less than 2% (2s), 2) For ages younger than 11,000 years we only keep points with uncertainties of less than 400 years. Two additional rules used to pick dates: 1) Use only one point per isochron – that with the lowest error bar, 2) When there is overlap between two ages within error, take the age with the smallest error bar. 

Rules for establishing length of a hiatus: After visually examining the stalagmites for indications of a hiatus, all potential bands were checked for missing years by extending the young part of the adjacent age constraints downward and the older age constraints upward. If there is a difference in predicted age at the visual band's depth that is larger than 400 years and the age difference is larger than the propagated uncertainty, we declare that band a hiatus. A hiatus' duration is taken to be the difference in age between the upper and lower age model constraints. 

UPDATE: 6/2008 (substitute revised age model) Corregendum, Nature 4 June 2009: A recalibration of the Caltech 236U and 229Th spike has determined that the original spike value used for the stalagmite chronologies yielded U-Th ages that were too old by a margin of ~2-3%. U-Th ages and subsequent age models have been recalculated using the new spike value for all stalagmites. The new age models alter the absolute timing of certain events, but do not alter any major conclusions of the original manuscript. The highest d18O values (inferred driest conditions) now occur at 16.0 +/- 0.3 kyr ago. A late deglacial d18O plateau in the Borneo stalagmite records is now centered at 13.0 +/- 0.2 kyr ago. The lowest d18O values (inferred wettest conditions) now occur at 5.0 +/- 0.1 kyr ago. Examples of original and adjusted dates, respectively, at 5 kyr intervals are as follows: 5280 versus 5141 (SSC01); 10581 versus 10293 (SSC01); 15673 versus 15231 (BA04); 20937 versus 20322 (BA04); and 26387 versus 25602 (SCH02).

UPDATE: 6/16/2011 (add spliced record)

LAST UPDATE: 8/4/2022 (updated spliced "master" record added) ** Both original citations Partin et al. 2007 (doi:10.1038/nature06164) and Buckingham et al. 2022 (doi:10.1029/2021GL096937) should be cited when using this updated spliced record! ** Notes for updated spliced "master" record: Spliced master record updated to include Mulu Secret Chamber stalagmite SC02 d18O, published in Buckingham et al., 2022 (doi:10.1029/2021GL096937). SC02 replaces SCH02 at the end of the deglaciation (12-15ka) in this updated spliced record as SC02 has the most reliable age model during that time period (see Buckingham et al., 2022). SC02 d18O values have been adjusted by +0.2 permil for the splice record, following the methods of Carolin et al., 2016 (doi:10.1016/j.epsl.2016.01.028).