The IntCal20 Northern Hemisphere Radiocarbon Age Calibration Curve (0–55 cal kBP)

Abstract

ABSTRACT Radiocarbon ( 14 C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14 C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14 C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14 C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14 C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14 C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.

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Affiliated Institutions

• Masaryk University CZ
• Swiss Federal Institute for Forest, Snow and Landscape Research CH
• Historic England GB
• Czech Academy of Sciences, Global Change Research Institute CZ
• University of Cambridge GB
• Aix-Marseille Université FR
• National Museum of Japanese History JP
• Aarhus University DK
• Environmental Earth Sciences AU
• Curt Engelhorn Centre Archaeometry DE
• University of Groningen NL
• University of Oxford GB
• Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung DE
• Lund University SE
• Oeschger Centre for Climate Change Research CH
• Nanjing Normal University CN
• Collège de France FR
• UNSW Sydney AU
• University of Bristol GB
• Centre National de la Recherche Scientifique FR
• University of California, Irvine US
• University of Glasgow GB
• University of Bologna IT
• University of Minnesota US
• University of California, Santa Cruz US
• University of Arizona US
• Christian-Albrechts-Universität zu Kiel DE
• Scottish Association For Marine Science GB
• University of St Andrews GB
• Lawrence Livermore National Laboratory US
• Institut de Recherche pour le Développement FR
• Centre de Recherche et d’Enseignement de Géosciences de l’Environnement FR
• Nagoya University JP
• University of Hohenheim DE
• University of Bern CH
• University of Waikato NZ
• Xi'an Jiaotong University CN
• Queen's University Belfast GB
• Woods Hole Oceanographic Institution US
• Cornell University US
• University of Sheffield GB
• Heidelberg University DE

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