Abrupt Increase of Radiocarbon Concentration in 660 BC in Tree Rings from Grabie Near Kraków (SE Poland)

Abstract

Abstract Miyake et al. (2012, 2013, 2014) described a sudden increase of radiocarbon ( 14 C) concentration in annual tree rings of Japanese cedar ( Cryptomeria japonica ) and Hinoki cypress ( Chamaecyparis obtusa) between AD 774 and 775 and between AD 993 and 994. In both analyzed periods, the sudden increase was observed almost in a single year. The increase in the 14 C content was about 12‰ in the period AD 774–775 (Miyake et al. 2012) and about 11.3‰ in the period AD 993–994 (Miyake et al. 2013, 2014; Fogtmann-Schultz et al. 2017; Rakowski et al. 2018). A similar increase was observed in 660 BC, with a peak height of about 10‰ (Park et al. 2017). Single-year samples of dendrochronologically dated tree rings of deciduous oak ( Quercus robur ) from Grabie, a village near Krakow (SE Poland), spanning the years 670–652 BC, were collected and their 14 C content was measured using an AMS technique. The results clearly show a rapid increase in the 14 C concentration in tree rings around 660 BC similar to this observed in Park et al. (2017).