Illuminating Intcal During the Younger Dryas

Bernd Kromer,Gerhard Helle,Jan Esper,Willy Tegel,Ulf Büntgen,Adam Sookdeo,Daniel Nievergelt,Kerstin Treydte,Michael Friedrich,Giulia Guidobaldi,Maren Pauly,Lukas Wacker,Frederick Reinig

doi:10.1017/rdc.2020.15

Abstract

ABSTRACTAs the worldwide standard for radiocarbon (14C) dating over the past ca. 50,000 years, the International Calibration Curve (IntCal) is continuously improving towards higher resolution and replication. Tree-ring-based 14C measurements provide absolute dating throughout most of the Holocene, although high-precision data are limited for the Younger Dryas interval and farther back in time. Here, we describe the dendrochronological characteristics of 1448 new 14C dates, between ~11,950 and 13,160 cal BP, from 13 pines that were growing in Switzerland. Significantly enhancing the ongoing IntCal update (IntCal20), this Late Glacial (LG) compilation contains more annually precise 14C dates than any other contribution during any other period of time. Thus, our results now provide unique geochronological dating into the Younger Dryas, a pivotal period of climate and environmental change at the transition from LG into Early Holocene conditions.

Highlights

The 2013 International Calibration Curve (IntCal13; Reimer et al 2013a) is the “gold standard” for geochronological 14C dating over the past ~50,000 years
Our results provide unique geochronological dating into the Younger Dryas, a pivotal period of climate and environmental change at the transition from Late Glacial (LG) into Early Holocene conditions
The combination of tree-ring width (TRW) cross-dating and high-resolution 14C wiggle-matching of 13 trees from Zurich closes the geochronological gap in the Younger Dryas (YD) (Figure 1b)

Summary

INTRODUCTION

The 2013 International Calibration Curve (IntCal13; Reimer et al 2013a) is the “gold standard” for geochronological 14C dating over the past ~50,000 years. Accounting for 14C/12C variations in various proxy archives of the Holocene (e.g., tree rings) and even well into the Pleistocene (e.g., plant macrofossils, speleothems, and corals), reservoir standardization and intercomparisons between hemispheres and archives are key factors for the establishment and maintenance of IntCal (Reimer et al 2013b). Due to their resolution and independent cross-dating (Büntgen et al 2018), tree-ring-based, annual to subdecadal 14C measurements form the backbone of the calibration curve throughout the Holocene. The exceptional quality (resolution) and quantity (replication) of this new LG 14C compilation significantly improves 14C wiggle-matching and dendrochronological cross-dating during the YD

MATERIAL AND METHODS

RESULTS AND DISCUSSION

CONCLUSIONS