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A record of the Southern Oscillation Index for the past 2,000 years from precipitation proxies



The El Niño-Southern Oscillation (ENSO) is a coupled ocean–atmosphere climate phenomenon in the tropical Pacific Ocean. The interannual climate variations have been shown to modify both the Hadley and Walker meridional and zonal atmospheric circulations, with strong impacts on global climate1,2,3. Proxy-based reconstructions of the Southern Oscillation Index on a multi-decadal scale have shown that the strength and frequency of El Niño occurrences have varied over the past millennium4,5,6,7. Here we compile reconstructions of precipitation8,9,10,11,12,13,14,15 from regions that experience substantial ENSO variability to extend the multidecadal-scale Southern Oscillation Index to include the past 2,000 years. We find that the Medieval Warm Period (AD 800–1300) was characterized by a negative index, which indicates more El Niño-dominated conditions, whereas during the Little Ice Age (AD 1400–1850) more La Niña-dominated conditions prevailed. The Southern Oscillation Index we derive is significantly correlated with reconstructions of solar irradiance and mean Northern Hemisphere temperature fluctuations.

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Figure 1: Locations of hydrological records.
Figure 2: SOIpr reconstruction.
Figure 3: Linkage between SOIpr, solar irradiance and Northern Hemisphere climate.

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Financial support for this research was provided by the Natural Science Foundation of China (NSFC) (40730107) and the Major State Basic Research Development Program of China (973 Program) (No.2010CB428902).

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H.Y., L.S. and Y.W. designed the study and wrote the paper; Y.W., W.H., S.Q. and C.Y. contributed to the statistical analysis and improving the English; all authors discussed the results and implications and commented on the manuscript at all stages.

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Correspondence to Liguang Sun.

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The authors declare no competing financial interests.

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Yan, H., Sun, L., Wang, Y. et al. A record of the Southern Oscillation Index for the past 2,000 years from precipitation proxies. Nature Geosci 4, 611–614 (2011).

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