More Rapid ¹⁴C Excursions in the Tree-Ring Record: A Record of Different Kind of Solar Activity at About 800 BC?

Abstract

ABSTRACT. Two radiocarbon ( 14 C) excursions are caused by an increase of incoming cosmic rays on a short time scale found in the Late Holocene , which are widely explained as due to extreme solar proton events (SPE). In addition, a larger event has also been reported at 5480 BC (Miyake et al. 2017a), which is attributed to a special mode of a grand solar minimum, as well as another at 660 BC (Park et al. 2017). Clearly, other events must exist, but could have different causes. In order to detect more such possible events, we have identified periods when the 14 C increase rate is rapid and large in the international radiocarbon calibration (IntCal) data (Reimer et al. 2013). In this paper, we follow on from previous studies and identify a possible excursion starting at 814-813 BC, which may be connected to the beginning of a grand solar minimum associated with the beginning of the Hallstatt period, which is characterized by relatively constant 14 C ages in the period from 800-400 BC. We compare results of annual 14 C measurements from tree rings of sequoia (California) and cedar (Japan), and compare these results to other identified excursions, as well as geomagnetic data. We note that the structure of the increase from 813 BC is similar to the increase at 5480 BC, suggesting a related origin. We also assess whether there are different kinds of events that may be observed and may be consistent with different types of solar phenomena, or other explanations.

Beyond megadrought and collapse in the Northern Levant: The chronology of Tell Tayinat and two historical inflection episodes, around 4.2ka BP, and following 3.2ka BP

“…Where this offset does apply, the effect is to achieve slightly later (more recent) calendar age estimates (something of potential relevance to debates over Iron Age chronology in the southern Levant, for example [ 179 ]). The very substantial change in atmospheric radiocarbon levels (the steep slope in the calibration curve) from the late 9 th through mid-8 th centuries BCE (linked with a major change in radiocarbon production and thence changes in solar activity processes [ 182 ]) ( S4 Fig ) clarifies that, regardless of any minor variations, the Tayinat Phase 2 Late 2 data are mid-8 th century BCE and thus likely represent the last pre-Assyrian conquest (738 BCE) phase at the site.…”

Causation of Late Quaternary Rapid-increase Radiocarbon Anomalies

“…The distance is from associated patches of H I and H II emission (Safi-Harb et al 2012), and there is also a central pulsar. The rapid rise, magnitude, and duration of the 14 C anomaly is compatible with causation by this close and powerful SN source, but abnormal solar activity has instead been invoked (Jull et al 2018;Miyake et al 2017). However, S165 is of appropriate age and distance to have caused this anomaly.…”

Composition and consequences of the IntCal20 radiocarbon calibration curve

“…The number of calibration-quality radiocarbon measurements on known-age tree rings, many of them single year, has proliferated especially since the discovery of rapid increases in atmospheric 14 C at AD 774–775 and AD 993 (Miyake et al, 2012, 2013). Other time periods have been targeted for single-ring measurements to search for additional 14 C events (e.g., Miyake et al, 2017a, 2017b; Jull et al, 2018) and to improve calibration around a radiocarbon plateau ca. 2700–2400 cal yr BP (Park et al, 2017; Fahrni et al, 2020), as well as to attempt to pinpoint the timing of the Minoan eruption of Santorini (Thera) (Pearson et al, 2018, 2020; Friedrich et al, 2020; Kuitems et al, 2020).…”