Hydroclimate variability over East Asia linked to ocean circulation, Antarctic and Pacific temperature changes during the LGM

Abstract

Characterization of the Asian summer monsoon (ASM) during the Last Glacial Maximum (LGM) would significantly improve our understanding of ASM dynamics in the current interglacial period. However, the variability of the ASM and its global teleconnection during the LGM remain unclear. Here we offer high-resolution δ¹³C and rather coarse Mg/Ca data from a stalagmite in southern China spanning 23.1 to 19.3 ka. This high-resolution δ¹³C record, generally corroborated by the Mg/Ca record, reveals an increase in ASM precipitation in southern China during 22–21 ka, a period of rapid growth in global ice volume. We propose that the high ASM precipitation was associated with the additional southward migration of the ASM rain belt and the strengthening of the Atlantic Meridional Overturning Circulation notwithstanding the significant ice accumulation. Furthermore, we show that the LGM was characterized by centennial and multi-centennial oscillations common to the Holocene Thermal Maximum (HTM). The common oscillations between the two different periods show that they are independent of global ice volume. Further studies show that the multi-centennial oscillations during the LGM are associated with changes in air temperature over Antarctica and sea surface temperature in the southeastern and tropical Pacific. These relationships demonstrate the influence of Antarctic temperature and El Niño-Southern Oscillation (ENSO) variability on ASM precipitation on the multi-centennial scale during the LGM. In conclusion, our analysis shows that the multi-scale changes in ASM precipitation in southern China are related to conditions in the ocean circulation and ENSO mode during the LGM. The persistent multi-centennial variations between the LGM and HTM indicate that the multi-centennial scale may be a viable window for estimating future ASM precipitation in southern China.