TY - JOUR
T1 - A multi-ice-core, annual-layer-counted Greenland ice-core chronology for the last 3800 years: GICC21
AU - Sinnl, Giulia
AU - Winstrup, Mai
AU - Erhardt, Tobias
AU - Cook, Eliza
AU - Jensen, Camilla Marie
AU - Svensson, Anders
AU - Vinther, Bo Mollesoe
AU - Muscheler, Raimund
AU - Rasmussen, Sune Olander
PY - 2022
Y1 - 2022
N2 - Ice-core timescales are vital for the understanding of past climate; hence they should be updated whenever significant amounts of new data become available. Here, the Greenland ice-core chronology GICC05 was revised for the last 3835 years by synchronizing six deep ice cores and three shallow ice cores from the central Greenland ice sheet. A new method was applied by combining automated counting of annual layers on multiple parallel proxies and manual fine-tuning. A layer counting bias was found in all ice cores because of site-specific signal disturbances; therefore the manual comparison of all ice cores was deemed necessary to increase timescale accuracy. After examining sources of error and their correlation lengths, the uncertainty rate was quantified to be 1 year per century. The new timescale is younger than GICC05 by about 13 years at 3835 years ago. The most recent 800 years are largely unaffected by the revision. Between 800 and 2000 years ago, the offset between timescales increases steadily, with the steepest offset occurring between 800 and 1100 years ago. Moreover, offset oscillations of about 5 years around the average are observed between 2500 and 3800 years ago. The non-linear offset behavior is attributed to previous mismatches of volcanic eruptions, to the much more extensive dataset available to this study, and to the finer resolution of the new ice-core ammonium matching. By analysis of the common variations in cosmogenic radionuclides, the new ice-core timescale is found to be in alignment with the IntCal20 curve (Reimer et al., 2020).
AB - Ice-core timescales are vital for the understanding of past climate; hence they should be updated whenever significant amounts of new data become available. Here, the Greenland ice-core chronology GICC05 was revised for the last 3835 years by synchronizing six deep ice cores and three shallow ice cores from the central Greenland ice sheet. A new method was applied by combining automated counting of annual layers on multiple parallel proxies and manual fine-tuning. A layer counting bias was found in all ice cores because of site-specific signal disturbances; therefore the manual comparison of all ice cores was deemed necessary to increase timescale accuracy. After examining sources of error and their correlation lengths, the uncertainty rate was quantified to be 1 year per century. The new timescale is younger than GICC05 by about 13 years at 3835 years ago. The most recent 800 years are largely unaffected by the revision. Between 800 and 2000 years ago, the offset between timescales increases steadily, with the steepest offset occurring between 800 and 1100 years ago. Moreover, offset oscillations of about 5 years around the average are observed between 2500 and 3800 years ago. The non-linear offset behavior is attributed to previous mismatches of volcanic eruptions, to the much more extensive dataset available to this study, and to the finer resolution of the new ice-core ammonium matching. By analysis of the common variations in cosmogenic radionuclides, the new ice-core timescale is found to be in alignment with the IntCal20 curve (Reimer et al., 2020).
U2 - 10.5194/cp-18-1125-2022
DO - 10.5194/cp-18-1125-2022
M3 - Journal article
SN - 1814-9324
VL - 18
SP - 1125
EP - 1150
JO - Climate of the Past
JF - Climate of the Past
IS - 5
ER -