Reconciling radiocarbon and ice core timescales over the Holocene – Cosmogenic radionuclides as synchronization tools

Abstract:

The atmospheric production rates of cosmogenic radionuclides, such as ¹⁴C and ¹⁰Be, vary globally due to external processes, namely the solar and geomagnetic modulation of the galactic cosmic ray flux as well as solar proton events. This signature is recorded in various archives such as ice cores (¹⁰Be) and tree-rings (¹⁴C). Hence, cosmogenic radionuclides offer a means to continuously assess timescale differences between two of the most widely used timescales in paleoclimatology – the radiocarbon and the ice core timescales. Short lived solar proton events additionally provide distinct marker horizons that allow synchronization of discrete horizons at annual precision.

We will present a cosmogenic radionuclide based synchronization of the Greenland ice core timescale (GICC05, Svensson et al., 2008) and the radiocarbon timescale (IntCal13, Reimer et al., 2013) over the Holocene. This synchronization allows radiocarbon dated and ice core paleoclimate records to be compared on a common timescale at down to sub-decadal precision. We will compare these results to independent discrete isochrones obtained from tephrochronology and solar proton events. In addition, we will discuss implications for the accuracy and uncertainty estimates of GICC05 over the Holocene.

Reimer, P. J., Bard, E., Bayliss, A., Beck, J. W., Blackwell, P. G., Bronk Ramsey, C., Buck, C. E., Cheng, H., Edwards, R. L., Friedrich, M., Grootes, P. M., Guilderson, T. P., Haflidason, H., Hajdas, I., Hatté, C., Heaton, T. J., Hoffmann, D. L., Hogg, A. G., Hughen, K. A., Kaiser, K. F., Kromer, B., Manning, S. W., Niu, M., Reimer, R. W., Richards, D. A., Scott, E. M., Southon, J. R., Staff, R. A., Turney, C. S. M., and van der Plicht, J.: IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP, Radiocarbon, 55, 1869-1887, 10.2458/azu_js_rc.55.16947, 2013.

Svensson, A., Andersen, K. K., Bigler, M., Clausen, H. B., Dahl-Jensen, D., Davies, S. M., Johnsen, S. J., Muscheler, R., Parrenin, F., Rasmussen, S. O., Röthlisberger, R., Seierstad, I., Steffensen, J. P., and Vinther, B. M.: A 60 000 year Greenland stratigraphic ice core chronology, Climate of the Past, 4, 47-57, 10.5194/cp-4-47-2008, 2008.