Accurate timescales are the backbone of palaeoclimatic and palaeoenvironmental reconstructions. Detailed comparison between land, ocean, and ice archives and their respective climate proxies requires high-resolution and accurate dating. For terrestrial and marine climate archives, calibration of radiocarbon (14C) dates provides a common timescale. However, for the time interval between 12.4 and 26 thousand calendar years B.P, i.e., beyond tree-ring-based calibration, the accepted radiocarbon calibration curve IntCal04 relies at present on marine 14C series, with associated uncertainties of the calendar scale. For ages older than 26 thousand calendar years B.P, there is no recommended calibration curve because of timescale discrepancies in the data sets covering that period. Dansgaard- Oeschger (D/O) and Heinrich events in ice cores provide useful templates for high-latitude climate sequences during the last glacial period. Annual layer counting provides an independent timescale, with counting errors caused by false identification of annual layers being small (several decades) in the Holocene. However, such errors may add up to several thousand years during Oxygen Isotope Stage (OIS) 3.
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