Radiocarbon changes in the XI century CE in annual tree rings

Abstract This paper presents new radiocarbon ( 14 C) measurements from annual tree rings of English oak ( Quercus robur L.) from Kujawy, Poland, spanning 1042–1062 CE. The results confirm an increase in Δ 14 C values between 1053 and 1055 CE, within the Oort Minimum of solar activity, consistent with literature values (Brehm et al. 2021a; Eastoe et al. 2019; Terrasi et al. 2020). The data reveal a sustained increase in Δ 14 C values between 1053 and 1055 CE, rising from −6.9 ± 1.8‰ to −2.6 ± 1.8‰. For the preceding period (1042–1052 CE), the average Δ 14 C value is −11.0 ± 1.9%, indicating a significant increase of 8.4 ± 2.6‰ toward 1055 CE. The study estimates the 14 C production rate during this period and suggests the radiocarbon increase likely began before 1054 CE, indicating it is unlikely to be significantly attributed to the supernova in 1054 CE. The study contributes to refining the understanding of rapid changes in atmospheric radiocarbon and their potential causes.