Millennial-scale variability in the Asian monsoon: Evidence from oxygen isotope records from stalagmites in southeastern China Jason Cosford a, ⁎, Hairuo Qing a , Daoxian Yuan b , Meiliang Zhang b , Chris Holmden c , William Patterson c , Cheng Hai d a Department of Geology, University of Regina, Regina, SK., Canada S4S 0A2 b Institute of Karst Geology, Chinese Academy of Geological Science, Guilin, 541004,China c Saskatchewan Isotope Laboratory, Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2 d Department of Geology and Geophysics, University of Minnesota, Twin Cities, MN, 55455, United States ABSTRACT ARTICLE INFO Article history: Accepted 25 March 2008 Keywords: Stalagmite Oxygen isotopes Millennial Monsoon Xiangshui Yaoba Don Two stalagmites from Xiangshui (X3) and Yaoba Don (YB1) Caves in southeastern China provide high- resolution δ 18 O time-series that exhibit prominent millennial-scale fluctuations in the intensity and character of the Asian monsoon for the period from 20,000 to 50,000 yr. B.P. Timing of these fluctuations, established by U-series disequilibrium ( 230 Th/ 234 U), correlates with Dansgaard–Oeschger events (2–13) and Heinrich events (H2–H5) recorded in the GISP2 ice core, indicating a climatic link between Asian monsoon circulation and air temperatures over the North Atlantic for much of the last glaciation. Although the exact mechanisms linking climatic fluctuations in the North Atlantic to those in eastern China have yet to be identified, climatic signals associated with changes in global ice volume and air temperatures over Greenland may be transferred to Asia by atmospheric mechanisms that affect the strength of the Siberian high-pressure cell and the amount of snow cover on the Tibetan Plateau, which force the intensity of the Asian monsoon. Another mechanism linking climate of the North Atlantic to the Asian monsoon relates to variation in oceanic circulation. Millennial-scale fluctuations in thermohaline circulation in the North Atlantic may have affected ocean currents in the tropical western Pacific Ocean, which is the moisture source for the East Asian monsoon. Despite the similarity of these paleoclimatic records and the implication of global teleconnections, the magnitude and timing of millennial-scale events at different locations in China reveal regional variations in climatic conditions. Comparisons of the δ 18 O curves from Xiangshui and Yaoba Don Cave stalagmites with those from Qixin Cave and Hulu Cave show general concordance between millennial-scale events, albeit with some notable differences among all the records. The well-studied Hulu Cave records show δ 18 O values that are lower than those of Xiangshui and Yaoba Don Caves, reflecting geographical differences. Hulu Cave is located near the eastern coast at a relatively low elevation dominated by the East Asian monsoon. By comparison, Xiangshui Cave and Yaoba Don Cave are further inland on the eastern slope of the Yunnan– Guizhou plateau, which receives precipitation from both the East Asian monsoon and quasi-stationary frontal systems. Rainfall contributed by the East Asian summer monsoon is relatively diminished in this region by these geographic and atmospheric circulation conditions, resulting in higher δ 18 O values. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Since the identification of Dansgaard–Oeschger (DO) events in Greenland ice cores (Dansgaard et al., 1993) and Heinrich events in marine cores from the North Atlantic (Heinrich, 1988), millennial-scale fluctuations have been recognized in numerous high-resolution climate records from different regions around the world, thereby suggesting a global manifestation (e.g. Behl and Kennett, 1996; Peterson et al., 2000; Leuschner and Sirocko, 2000; Blunier and Brook, 2001). In regions dominated by the East Asian monsoon, millennial-scale climate variability has been identified in marine cores recovered from the South China Sea (Wang et al., 1999), the Sulu Sea (Dannenmann et al., 2003), and the West Pacific Warm Pool (Stott et al., 2002), as well as in terrestrial archives, such as loess–paleosol successions (An, 2000), Tibetan ice cores (Thompson et al., 1997), lacustrine cores (Hodell et al., 1999) and speleothems (Wang et al., 2001). Although paleoclimatic reconstructions based on these records demonstrate strengthened summer monsoonal circulation during interstadials and increased winter monsoonal circulation during stadials, evaluation of the phase Palaeogeography, Palaeoclimatology, Palaeoecology 266 (2008) 3–12 ⁎ Corresponding author. E-mail address: cosford@jdmollard.com (J. Cosford). 0031-0182/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2008.03.029 Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo