Natural Radiocarbon Variations from AD 200 to 800

Abstract

High precision radiocarbon measurements (+/- 2.5 per mil STD) were carried out on absolutely dated European oak material. These showed that significant shortterm atmospheric 14C variations of up to 2 percent occurred between AD 200 and 800. These changes, reflecting a 150-to 180-year periodicity, seem to correlate with the average sunspot activity around that time. In comparison with results obtained by other authors, a very regular pattern of natural atmospheric 14C variations is exhibited.