Tree rings reveal globally coherent signature of cosmogenic radiocarbon events in 774 and 993 CE
Abstract
Though tree-ring chronologies are annually resolved, their dating has never been independently validated at the global scale. Moreover, it is unknown if atmospheric radiocarbon enrichment events of cosmogenic origin leave spatiotemporally consistent fingerprints. Here we measure the 14C content in 484 individual tree rings formed in the periods 770–780 and 990–1000 CE. Distinct 14C excursions starting in the boreal summer of 774 and the boreal spring of 993 ensure the precise dating of 44 tree-ring records from five continents. We also identify a meridional decline of 11-year mean atmospheric radiocarbon concentrations across both hemispheres. Corroborated by historical eye-witness accounts of red auroras, our results suggest a global exposure to strong solar proton radiation. To improve understanding of the return frequency and intensity of past cosmic events, which is particularly important for assessing the potential threat of space weather on our society, further annually resolved 14C measurements are needed.
Citation
Büntgen , U , Wacker , L , Galván , J D , Arnold , S , Arseneault , D , Baillie , M , Beer , J , Bernabei , M , Bleicher , N , Boswijk , G , Bräuning , A , Carrer , M , Ljungqvist , F C , Cherubini , P , Christl , M , Christie , D A , Clark , P W , Cook , E R , D’Arrigo , R , Davi , N , Eggertsson , Ó , Esper , J , Fowler , A M , Gedalof , Z , Gennaretti , F , Grießinger , J , Grissino-Mayer , H , Grudd , H , Gunnarson , B E , Hantemirov , R , Herzig , F , Hessl , A , Heussner , K-U , Jull , A J T , Kukarskih , V , Kirdyanov , A , Kolář , T , Krusic , P J , Kyncl , T , Lara , A , LeQuesne , C , Linderholm , H W , Loader , N J , Luckman , B , Miyake , F , Myglan , V S , Nicolussi , K , Oppenheimer , C , Palmer , J , Panyushkina , I , Pederson , N , Rybníček , M , Schweingruber , F H , Seim , A , Sigl , M , Churakova (Sidorova) , O , Speer , J H , Synal , H-A , Tegel , W , Treydte , K , Villalba , R , Wiles , G , Wilson , R , Winship , L J , Wunder , J , Yang , B & Young , G H F 2018 , ' Tree rings reveal globally coherent signature of cosmogenic radiocarbon events in 774 and 993 CE ' Nature Communications , vol. 9 , 3605 . https://doi.org/10.1038/s41467-018-06036-0
Publication
Nature Communications
Status
Peer reviewed
ISSN
2041-1723Type
Journal article
Rights
© The Author(s) 2018. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
Description
This study was funded by the WSL-internal COSMIC project (5233.00148.001.01), the ETHZ (Laboratory of Ion Beam Physics), the Swiss National Science Foundation (SNF Grant 200021L_157187/1), and as the Czech Republic Grant Agency project no. 17-22102s.Collections
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