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Causes of an ad 774–775 14C increase



Arising from F. Miyake, K. Nagaya, K. Masuda & T. Nakamura Nature 486, 240–242 (2012)10.1038/nature11123

Atmospheric 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 events1. We find that the coronal mass ejection energy based on 14C production is much smaller than claimed in ref. 1, but still substantially larger than the maximum historical Carrington Event of 18592,3,4. Such an event would cause great damage to modern technology5,6, and in view of recent confirmation of superflares on solar-type stars7,8, this issue merits attention.

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Figure 1: Percentage change in globally averaged O3 column density.

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A.L.M. planned and wrote the paper with the assistance of B.C.T. B.C.T. performed the atmospheric computations and made the plot.

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Correspondence to Adrian L. Melott.

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Melott, A., Thomas, B. Causes of an ad 774–775 14C increase. Nature 491, E1–E2 (2012).

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