Richards
David A.
Richards
David A.
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ArticleDevelopment of the IntCal database(Cambridge University Press, 2023-07-28) Bronk Ramsey, Christopher ; Adolphi, Florian ; Austin, William ; Bard, Edouard ; Bayliss, Alex ; Blaauw, Maarten ; Cheng, Hai ; Edwards, R. Lawrence ; Friedrich, Michael ; Heaton, TimothyThe IntCal family of radiocarbon (14C) calibration curves is based on research spanning more than three decades. The IntCal group have collated the 14C and calendar age data (mostly derived from primary publications with other types of data and meta-data) and, since 2010, made them available for other sorts of analysis through an open-access database. This has ensured transparency in terms of the data used in the construction of the ratified calibration curves. As the IntCal database expands, work is underway to facilitate best practice for new data submissions, make more of the associated metadata available in a structured form, and help those wishing to process the data with programming languages such as R, Python, and MATLAB. The data and metadata are complex because of the range of different types of archives. A restructured interface, based on the “IntChron” open-access data model, includes tools which allow the data to be plotted and compared without the need for export. The intention is to include complementary information which can be used alongside the main 14C series to provide new insights into the global carbon cycle, as well as facilitating access to the data for other research applications. Overall, this work aims to streamline the generation of new calibration curves.
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ArticleThe Intcal20 Northern Hemisphere radiocarbon age calibration curve (0-55 cal kBP)(Cambridge University Press, 2020-08-12) Reimer, Paula J. ; Austin, William E. N. ; Bard, Edouard ; Bayliss, Alex ; Blackwell, Paul G. ; Bronk Ramsey, Christopher ; Butzin, Martin ; Cheng, Hai ; Edwards, R. Lawrence ; Friedrich, Michael ; Grootes, Pieter M. ; Guilderson, Thomas P. ; Hajdas, Irka ; Heaton, Timothy J. ; Hogg, Alan G. ; Hughen, Konrad A. ; Kromer, Bernd ; Manning, Sturt W. ; Muscheler, Raimund ; Palmer, Jonathan G. ; Pearson, Charlotte ; van der Plicht, Johannes ; Reimer, Ron W. ; Richards, David A. ; Scott, E. Marian ; Southon, John R. ; Turney, Christian S. M. ; Wacker, Lukas ; Adolphi, Florian ; Büntgen, Ulf ; Capano, Manuela ; Fahrni, Simon M. ; Fogtmann-Schulz, Alexandra ; Friedrich, Ronny ; Köhler, Peter ; Kudsk, Sabrina ; Miyake, Fusa ; Olsen, Jesper ; Reinig, Frederick ; Sakamoto, Minoru ; Sookdeo, Adam ; Talamo, SahraRadiocarbon (14C) 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 14C 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 14C 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 14C 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 14C 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 14C 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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ArticleIntCal09 and Marine09 radiocarbon age calibration curves, 0–50,000 years cal BP(Dept. of Geosciences, University of Arizona, 2009-12) Reimer, Paula J. ; Bard, Edouard ; Bayliss, Alex ; Beck, J. Warren ; Blackwell, Paul G. ; Bronk Ramsey, Christopher ; Buck, Caitlin E. ; Cheng, Hai ; Edwards, R. Lawrence ; Friedrich, Michael ; Grootes, Pieter M. ; Guilderson, Thomas P. ; Haflidason, Haflidi ; Hajdas, Irka ; Hatte, Christine ; Heaton, Timothy J. ; Hoffmann, Dirk L. ; Hogg, Alan G. ; Hughen, Konrad A. ; Kaiser, K. Felix ; Kromer, Bernd ; Manning, Sturt W. ; Niu, Mu ; Reimer, Ron W. ; Richards, David A. ; Scott, E. Marian ; Southon, John R. ; Staff, Richard A. ; Turney, Christian S. M. ; van der Plicht, JohannesThe IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and other carbonates and for quantification of uncertainty in both the 14C and calendar timescales as established in 2002. No change was made to the curves from 0–12 cal kBP. The curves were constructed using a Markov chain Monte Carlo (MCMC) implementation of the random walk model used for IntCal04 and Marine04. The new curves were ratified at the 20th International Radiocarbon Conference in June 2009 and are available in the Supplemental Material at www.radiocarbon.org.