Radiocarbon Concentration in the Atmosphere: 8000-Year Record of Variations in Tree Rings: First Results of a USA Workshop

Abstract

Radiocarbon dates calculated from the ratio of modern carbon-14 activity and sample activity and the half-life of carbon-14 need to be calibrated to compensate for temporal variations in the concentration of carbon-14 in the atmosphere. Development of a suitable calibration scheme has been an ongoing process of the last twenty years, ever since the discovery of variations in historical times of the atmospheric radiocarbon content which parallel climatic and solar phenomena (de Vries, 1958; 1959) and the recent depletion due to industrial effects (Suess, 1955).