Coupled atmosphere-ice-ocean dynamics during Heinrich Stadial 2

Our understanding of climate dynamics during millennial-scale events is incomplete, partially due to the lack of their precise phase analyses under various boundary conditions. Here we present nine speleothem oxygen-isotope records from mid-to-low-latitude monsoon regimes with sub-centennial age precision and multi-annual resolution, spanning the Heinrich Stadial 2 (HS2) - a millennial-scale event that occurred at the Last Glacial Maximum. Our data suggests that the Greenland and Antarctic ice-core chronologies require +320- and +400-year adjustments, respectively, supported by extant volcanic evidence and radiocarbon ages. Our chronological framework shows a synchronous HS2 onset globally. Our records precisely characterize a centennial-scale abrupt "tropical atmospheric seesaw" superimposed on the conventional "bipolar seesaw" at the beginning of HS2, implying a unique response/feedback from low-latitude hydroclimate. Together with our observation of an early South American monsoon shift at the HS2 termination, we suggest a more active role of low-latitude hydroclimate dynamics underlying millennial events than previously thought.Published versionThis work was supported by the National Nature Science Foundation of China (NSFC grants 41731174, 41888101, and 42150710534 to H.C., NSFC grants 41703007 and 42172201 to G.K.), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB 40000000) to Z.A., the FAPESP 2017/50085-3 to F.W.C., and the Carlsberg Foundation via the grant to SOR’s ChronoClimate project