Records showing ENSO and East Asian monsoon variations over the past 8000 yrs. (a) ENSO frequency recorded in sediments from southern Ecuador [after Moy et al., 2002]; (b) SST and relative salinity of the SCS derived from corals, with higher SST and higher Dd 18 O (reflecting more saline seawater due to transportation of more moisture out of the tropics) indicating strong East Asian summer monsoon [after Yu et al., 2005]. (c) Speleothem d 18 O record of Dongge Cave, southern China, reflecting the history of the East Asian summer monsoon precipitation [after Y. J. Wang et al., 2005]. The two shaded bars correspond to the periods of SCS DR plateaus. The ENSO and the East Asian monsoon intensity variations are broadly consistent with our coral R and DR records from both the long‐term trend and the short‐term oscillations.  

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... Both modeling and proxy record reconstructions suggest that ENSO frequency and intensity was strengthen- ing, whereas EASM progressively weakening since early Holocene, despite significant shorter-term fluctuations Moy et al., 2002; P. X. Wang et al., 2005;Yu et al., 2005]. The overall DR trend in the SCS during the past 7500 years is generally consistent with the changes of ENSO and EASM activities (Figure 4). For instance, the mean DR values on millennial scale were generally decreas- ing from 7 ka to recent. ...

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... In addition to the above mentioned long-term trend, there is mounting evidence from coral and lake sediment records in the Pacific region to suggest ENSO frequency and amplitude during the mid-Holocene (e.g., 7.5-5.6 cal ka BP) were significantly lower [McGregor and Gagan, 2004;Moy et al., 2002] (Figure 4a). In addition, stalagmite, lake sediment, marine sediment and coral records all consistently suggest that SST in the SCS was warmer, sea level was higher, and EASM was stronger than present during this period [Wei et al., 2007;Yu et al., 2004bYu et al., , 2005Yu et al., , 2009aYu, 2002, 2007]. ...

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... BP was particularly stormy in the southern SCS, reflecting more intensive summer monsoon activity [Yu et al., 2009a]. On the other hand, according to Moy et al. [2002], ENSO frequency was relatively lower prior to 2.5 ka BP than after 2.5 ka BP (Figure 4a), although this record is based on low-resolution radiocarbon dating and its timescale may not be precisely comparable to the 230 Th-date- based records [Yu et al., 2009a]. All these evidences tend to suggest that ENSO was relatively weaker during 3.5-2.5 cal ka BP, whereas EASM stronger, which may explain the observed DR plateau (weighted mean of 89 ± 59 yrs) for this period, with the ENSO probably playing a major role in controlling observed elevated DR. ...

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... these evidences tend to suggest that ENSO was relatively weaker during 3.5-2.5 cal ka BP, whereas EASM stronger, which may explain the observed DR plateau (weighted mean of 89 ± 59 yrs) for this period, with the ENSO probably playing a major role in controlling observed elevated DR. It is noted that the Dongge speleothem d 18 O record (Figure 4c) does not seem to reflect stronger EASM during 3.5-2.5 ka, which appears to be at variance with both Chinese historic record [Chu, 1973] and summer SST and storm records in the SCS [Yu et al., 2005[Yu et al., , 2009b. However, it was also the period during which the speleothem d 18 O records from different sites surrounding the SCS in tropical to sub-tropical Western Pacific region dis- agree with each other (see comparison in Figure 2 of Griffiths et al., 2009]), possibly related to competing factors influ- encing the speleothem d 18 O. ...

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... particular, as DR in South Peru is strongly influenced by coastal upwelling which is in turn controlled by ENSO, enhanced coastal upwelling intensity bringing more 14 C-depleted upwelled waters to the surface ocean was thought to be a major reason for highly elevated DR values for South Peru during 7.4-6.9 cal ka BP [Fontugne et al., 2004], a period where ENSO was signifi- cantly reduced (Figure 4). For PNG, strengthened trade winds during a period of reduced ENSO between 7.2 and 5.8 cal ka BP would enhance air-sea exchange in the southern branch of the Pacific South Equatorial Current which feeds its northern coast. ...

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... ka BP with elevated SCS DR broadly corresponding to elevated DR for South Peru and reduced DR for northern coastal PNG. This may indicate smaller variations in DR for the Pacific for the period 4.0-2.1 cal kyr BP which might be associated with reduced ENSO for most of the time during the interval ∼4.5-1.8 cal ka BP (Figure 4a). More experimental data from the Pacific during this time interval are required to confirm this pattern in DR changes. ...