Summer monsoon precipitation variations in central China over the past 750 years derived from a high-resolution absolute-dated stalagmite

摘要

A 2-3-year resolution record of stalagmite oxygen isotope variations from the south flank of the Qinling Mountains, central China, has revealed the Asian summer monsoon (ASM) precipitation variations in the investigated area over the past 750 years. The summer monsoon precipitation gradually increased since 1249 AD, reaching its highest values in the period 1535-1685 AD, and then decreased with substantial clecadal- to centennial-scale fluctuations. The monsoon precipitation increased again between 1920 and 1970 AD. Three intervals of high monsoon precipitation were identified: 1535-1685 AD, 1755-1835 AD, and 1920-1970 AD. Three intervals of low precipitation were inferred in 1249-1325 AD. 1390-1420 AD, and 1890-1915 AD. The delta O-18 composition and lithological features of the stalagmite coincidently indicate a wetter climate during the Little Ice Age (LIA), which is also confirmed by climate records from Chinese historical documents within this area. A comparison with other high-resolution speleothem records indicates regional differences in monsoon precipitation variability from the south to the north of central China in the last 750 years on clecadal- to centennial-scale. Power spectrum analysis of the delta O-18 record shows significant 117.8-, 34.6-, 14, 10.3-, and similar to 6-year periodicities. These periodicities are widely observed in the climate records from ASM-controlled areas of China and are consistent with the Gleissburg periodicity, Bruckner periodicity, sunspot periodicity of solar activity, and El Nino-Southern Oscillation (ENSO) periodicity. These correlations suggest that both solar activity and ENSO periodicity may have had important influences on ASM precipitation in China over the past 750 years.