Changes in the Asian monsoon climate during the late last interglacial recorded in oxygen isotopes of a stalagmite from the Yongxing Cave, central China

Abstract

The last interglacial contains information about how climate behaves during a warm period comparable to the current interval. However, there is no consensus on the key signatures and force of the last interglacial climate changes at present. Here we present a high-resolution stalagmite oxygen isotope record from central China, which spans from 123.3 to 116.8 ka. The stalagmite δ18O time-series bears a resemblance to changes in Northern Hemisphere summer insolation before the demise of the last interglacial, like the condition during the Holocene. Superimposed on the long-term δ18O record is a pronounced shift to more positive values at around 121.6 ka, indicating a switch of the Asian monsoon mean state into a weaker condition. This monsoon shift correlates with a decrease in the mean state of the South American Summer Monsoon, and a well-known abrupt mid-Eemian cooling event at high latitudes. These correlations indicate broad-scale features of the climate shift over the warm last interglacial. Another positive δ18O shift of up to 3.5‰ occurred at around 120 ka, representing the demise of the last interglacial Asian monsoon. By comparing the stalagmite δ18O records against changes in ice volume and summer insolation during the last interglacial and recent Holocene, respectively, we conclude that the decreasing Northern Hemisphere summer insolation dominated the rapid demise of the last interglacial in the Asian monsoon region.