Greenland Ice Core GICC05 and Speleothem U/Th Timescale Differences 11-45 kaBP Adolphi, F.; Bronk Ramsey, C.; Erhardt, T.; Edwards, R.L.; Cheng, H.; Turney, C.S.M.; Cooper, A.; Svensson, A.M.; Rasmussen, S.O.; Fischer, H.; Muscheler, R. Adolphi, F. Bronk Ramsey, C. Erhardt, T. Edwards, R.L. Cheng, H. Turney, C.S.M. Cooper, A. Svensson, A.M. Rasmussen, S.O. Fischer, H. Muscheler, R. earth science/paleoclimate/ice core (Greenland>LATITUDE >LONGITUDE ) 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. STUDY NOTES: Evaluation and estimation of offsets between GICC05 Greenland ice core timescale and U/Th-dated speleothems 11,000 to 45,000 years ago. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Adolphi, F. Investigator : Bronk Ramsey, C. Investigator : Erhardt, T. Investigator : Edwards, R.L. Investigator : Cheng, H. Investigator : Turney, C.S.M. Investigator : Cooper, A. Investigator : Svensson, A.M. Investigator : Rasmussen, S.O. Investigator : Fischer, H. Investigator : Muscheler, R. 2018-11-23 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/25631 https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/adolphi2018gicc05-u-th.txt https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/adolphi2018gicc05-u-th.txt English https://www.ncdc.noaa.gov/paleo/study/25631 https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/adolphi2018gicc05-u-th.txt Florian Adolphi, Christopher Bronk Ramsey, Tobias Erhardt, R. Lawrence Edwards, Hai Cheng, Chris S. M. Turney, Alan Cooper, Anders Svensson, Sune O. Rasmussen, Hubertus Fischer, and Raimund Muscheler2018Connecting the Greenland ice-core and U/Th timescales via cosmogenic radionuclides: testing the synchroneity of Dansgaard-Oeschger eventsClimate of the Past14111755-178110.5194/cp-14-1755-2018https://www.clim-past.net/14/1755/2018/cp-14-1755-2018.html START YEAR: 45000 cal yr BP * END YEAR: 11000 cal yr BP -60 60 -20 82