During the last glacial period Northern Hemisphere climate was characterized by extreme and abrupt climate changes, so-called Dansgaard-Oeschger (DO) events. Most clearly observed as temperature changes in Greenland ice-core records, their climatic imprint was geographically widespread. However, the temporal relation between DO events in Greenland and other regions is uncertain due to the chronological uncertainties of each archive, limiting our ability to test hypotheses of synchronous change. In contrast, the assumption of direct synchrony of climate changes forms the basis of many timescales. Here, we use cosmogenic radionuclides (10Be, 36Cl, 14C) to link Greenland ice-core records to U=Th-dated speleothems, quantify offsets between the two timescales, and improve their absolute dating back to 45 000 years ago. This approach allows us to test the assumption that DO events occurred synchronously between Greenland ice-core and tropical speleothem records with unprecedented precision. We find that the onset of DO events occurs within synchronization uncertainties in all investigated records. Importantly, we demonstrate that local discrepancies remain in the temporal development of rapid climate change for specific events and speleothems. These may either be related to the location of proxy records relative to the shifting atmospheric fronts or to underestimated U=Th dating uncertainties. Our study thus highlights the potential for misleading interpretations of the Earth system when applying the common practice of climate wiggle matching.
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Acknowledgements. FA was supported through a grant by the Swedish Research Council (Vetenskapsrådet no. 2016-00218). CBR was partially supported through the UK Natural Environment Research Council (NERC) Radiocarbon Facility (NRCF010002). TE and HF acknowledge the long-term support of ice-core research at the University of Bern by the Swiss National Science Foundation (SNSF) and the Oeschger Center for Climate Change Research. SOR gratefully acknowledges support from the Carlsberg Foundation to the project ChronoClimate. This work was partially supported by the Swedish Research Council (grant DNR2013-8421 to RM), the NSF 1702816 to RLE, and the Australian Research Council DP170104665 to CT and AC. We gratefully acknowledge the financial support of the University of Adelaide Environment Institute for the initial Marble Hill meeting that initiated this work.