An exceptionally strengthened East Asian summer monsoon event between 19.9 and 17.1 ka BP recorded in a Hulu stalagmite

A stalagmite-based isotope record (No. H82) from Nanjing Hulu Cave, spanning from 16.5 to 10.3 ka BP, provided strong evidence for a coherence relation between the East Asian summer monsoon (EASM) and the North Atlantic climates on millennial time scales. Here we extend the high-resolution δO time series back to 22.1 ka BP with additional 7 Th dates and 573 stable isotope measurements on the lower part of that sample. The new record with a decadal resolution, piecing together with the previous data, provides a detailed, complete Last Glacial Maximum (LGM)/deglacial history of the EASM. Two centennial-scale weak monsoon events are detected within the analogue H1 event, and can be correlated to corresponding Greenland temperature shifts. This suggests a rapid re-organization of atmospheric and oceanic circulations during the ice-rafted debris (IRD) event in North Atlantic. A strengthened EASM event spanning from 19.9 to 17.1 ka BP, firstly reported here, reaches on average a half of the monsoon intensity of Bølling warming with its peak close to the full level. Taking all available evidence from continental and oceanic sediments into consideration, we suggest that a forcing mechanism behind the event would be a positive feedback of the tropical Pacific Super-ENSO cycles in response to precessional changes in solar irradiation. © Science in China Press and Springer-Verlag GmbH 2009.