Causes of an ad 774–775 14C increase

@article{Melott2012CausesOA,
  title={Causes of an ad 774–775 14C increase},
  author={Adrian L. Melott and Brian C. Thomas},
  journal={Nature},
  year={2012},
  volume={491},
  pages={E1-E2}
}
Arising from F. Miyake, K. Nagaya, K. Masuda & T. Nakamura 486, 240–242 (2012)10.1038/nature11123Atmospheric 14C production is a potential window into the energy of solar proton and other cosmic ray events. It was previously concluded that 14C results from ad 774–775 would require solar events that were orders of magnitude greater than known past events. We find that the coronal mass ejection energy based on 14C production is much smaller than claimed in ref. 1, but still substantially larger… 
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TLDR
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Another rapid event in the carbon-14 content of tree rings.
TLDR
New ( 14)C measurements from AD 822 to 1020, and the discovery of a second rapid increase of (14)C content from AD 992 to 993 are reported, suggesting that solar activity is a plausible cause of the (14), and it is highly possible that these events have the same origin.
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