EVOLUTION OF RADIOCARBON CALIBRATION

Paula J Reimer

doi:10.1017/rdc.2021.62

Abstract

ABSTRACTIn the late 1950s it was recognized that levels of atmospheric radiocarbon (14C) had not been constant over time. Since then, researchers have sought to document those changes, initially through measurements of known age tree rings and more recently using other archives to create curves to correct or calibrate radiocarbon ages to calendar ages. This paper highlights some, but by no means all, of the efforts to create and extend radiocarbon calibration curves.

Highlights

Not long after James Arnold and Willard Libby published the “Curve of Knowns” as preliminary proof that radiocarbon (14C) dating worked at least for the past 5000 years (Arnold and Libby 1949), researchers began to evaluate the validity of two of the fundamental assumptions of the method
Stuiver and Suess (1966) analyzed known age tree rings from European oak, North American Douglas fir and sequoia at La Jolla and Yale relative to the oxalic acid standard provided by the U.S National Bureau of Standards (NBS)
They published tables of radiocarbon corrections and what amounts to the first radiocarbon calibration curve extending from AD 1000 to 1800 (Figure 2)

Summary

THE EARLY YEARS

Not long after James Arnold and Willard Libby published the “Curve of Knowns” as preliminary proof that radiocarbon (14C) dating worked at least for the past 5000 years (Arnold and Libby 1949), researchers began to evaluate the validity of two of the fundamental assumptions of the method. Stuiver and Suess (1966) analyzed known age tree rings from European oak, North American Douglas fir and sequoia at La Jolla and Yale relative to the oxalic acid standard provided by the U.S National Bureau of Standards (NBS) They published tables of radiocarbon corrections and what amounts to the first radiocarbon calibration curve extending from AD 1000 to 1800 (Figure 2). The Klein et al (1982) calibration curve was based on dendrochronologically dated trees, primarily bristlecone pine and sequoia of 20 or fewer rings measured at the Universities of Figure 3 A section of the calibration curve from AD 600–1950 with 90% confidence limits for radiocarbon errors of 20, 100, 200, and 300 14C yr (from Klein et al 1982: Fig. 3A). Mook as chairman was re-constituted for the 1982–1985 interval” (Stuiver 1983)

THE STUIVER YEARS

Findings

THE INTCAL WORKING GROUP