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Abstract Cosmic rays and solar energetic particles pose significant risks to satellites, space stations, and human space exploration. They also produce atmospheric radiocarbon (14C), which enters the carbon cycle and is recorded by paleoenvironmental proxies. Miyake events, rapid increases in atmospheric14C, first identified in annual tree rings and later confirmed through ice core10Be and36Cl isotopes, are thought to result from extreme solar activity, are seven events identified over the last 14,300 years. However, uncertainty in annual14C measurements limits precise inferences about their timing and magnitude. This study examines uncertainties in14C during two Miyake events (774 CE and 993 CE) across trees with differing uptake, storage, and allocation of carbon. We hypothesize that tree species physiology affects tree‐ring Δ14C, with deciduous species recording lagged, attenuated tree‐ring Δ14C relative to evergreen species. Using Δ14C data from pine and larch in Mongolia and a larger multi‐species Northern Hemisphere data set, we employed a Bayesian framework to estimate the timing, duration, and magnitude of these two events. Our AMS results showed no differences in Δ14C between evergreen and deciduous species growing at similar sites during the 774 CE event. The 993 CE event was variable, but parameter estimates were consistent between species. Northern Hemisphere comparisons indicated that annual series of Δ14C from evergreen and deciduous conifers yielded relatively more precise modeled estimates of start date and duration relative to deciduous broadleaf species. Future studies should consider the role of species‐specific carbon allocation strategies and storage dynamics in determining the radiocarbon response to Miyake events.
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This content will become publicly available on December 10, 2025
Evaluating possible sources of error in tree-ring 14 C data using multiple trees across South America
Abstract A limitation in fine-tuned tree-ring radiocarbon (14C) data is normally associated with overall data uncertainty. Tree-ring14C data variance as a result of sample heterogeneity can be reduced by adopting best practices at the time of sample collection and subsequent preparation and analysis. Variance-reduction of14C data was achieved by meticulous sample handling during increment core or cross-sectional cuttings, in-laboratory wood reductions, and cellulose fiber homogenization of whole rings. To demonstrate the performance of those procedures to final14C results, we took advantage of the replicated data from assigned calendar years of two Pantropical post-1950 AD tree-ring14C reconstructions. TwoCedrela fissilisVell. trees spaced 22.5 km apart, and two trees of this species together with onePeltogyne paniculataBenth tree spaced 0.2 to 5 km apart were sampled in a tropical dry and moist forest, respectively. Replicate14C data were then obtained from grouped tree-ring samples from each site. A total of 88% of the replicated14C results fell into a remarkably consistent precision/accuracy range of 0.3% or less, even though multiple tree species were used as pairs/sets. This finding illustrates how adopting a few simple strategies, in tandem with already established chemical extraction procedures and high-precision14C analysis, can improve14C data results of tropical trees.
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- Award ID(s):
- 1903690
- PAR ID:
- 10565428
- Publisher / Repository:
- Cambridge University Press
- Date Published:
- Journal Name:
- Radiocarbon
- ISSN:
- 0033-8222
- Page Range / eLocation ID:
- 1 to 16
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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